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CLASS 356,	OPTICS: MEASURING AND TESTING
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SECTION I - CLASS DEFINITION

A. This class includes methods and apparatus (1) for analyzing light to measure or test its characteristics, such as intensity, color and polarization; (2) for determining the optical or nonoptical properties of materials or articles by noting, as by inspection, measurement, or test the effect produced by the materials or articles on light associated therewith; and (3) for measuring the dimensions of structures or the spatial relationships such as distances or angle bearings of spaced points by comparison of the respective properties (usually direction or spatial position) of the light from these points or by comparison of the properties of these lights with some scale or standard. The light analyzing includes or is for spectroscopy, interference, polarization, beam direction or pattern, focal position of a light source, shade or color, and photometers. The material or article properties determined are or involve crystal or gem examination, material strain analysis, blood analysis, optical pyrometers, egg candling, cutting blade sharpness, oil testing, document verification, flatness, lens or reflector testing, refraction testing, monitoring moving webs or fabrics, light transmission or absorption, light reflection, inspection for flaws or imperfections in materials, and thread counting.

The dimensioning and spatial relationship determination includes triangulation by a light beam, contour plotting, range or height finders, motion stopping, velocity or velocity/height measuring, sighting where the optical element or reticle moves with the sighted object, particle size determination, particle light scattering, electrophoresis, angle measuring or axial alignment, mensuration or configuration comparison, alignment in a lateral direction, and fiducial instruments.

B. Included also are apparatus and methods to facilitate the viewing of structure as for flaws and imperfections. The structure is usually optically significant such as transparent sheets or bottles or semi-transparent cloth; or the structure is inaccessible as a bore requiring a bore scope. Included also are methods and structure for preparing the sample for an optical test, and optical test standards.

C. Included also are apparatus and methods involving a plurality of measurements or tests each within the scope of this class; and also included are a measurement or test within the scope of this class together with a measurement or test or other art structure provided, per se, elsewhere, but where no provision for the combination is made elsewhere.

SECTION II - LINES WITH OTHER CLASSES AND WITHIN THIS CLASS

A. OPTICAL MEASURING OR TESTING CLASSIFIED ELSEWHERE

Class 33 provides for optical measurements of the light ray type within the scope of this class. See "Geometrical Instruments in This Class and in Class 33," section C, below, for the subject matter placed in Class 33 and Class 356. Class 73 includes optical measuring and testing within the scope of its subclasses. See "Measuring and Testing in This Class and Class 73," section D, below, for the line between Class 73 and Class 356. Signal and indicating apparatus which may involve optics are classified elsewhere. See, for example, temperature, radiant energy, smoke, or gas indicators. Surgical diagnostic instruments which may involve optical measuring or testing on or in the body are elsewhere. Television systems for measuring and testing which may include optical elements are classified elsewhere. Photocells and associated circuitry together with optical structure which may involve measuring or testing are classified elsewhere. However, this Class 356 includes optical testing with a photoelectric light detector and usually claiming either an indicator or structure to support or contain the specimen or sample under test. Lamp and discharge device testing is classified elsewhere. Eye examining and testing instruments which may include optical measuring or testing are elsewhere. (See Subclass References to the Current Class and References to Other Classes, below, for subclass references of subject matter above.)

B. TESTING AND MEASURING SUBCOMBINATIONS PROVIDED FOR ELSEWHERE

Optical elements which may be used in measuring and testing apparatus are classified elsewhere as are the conventional optical elements such as lenses, prisms, and mirrors. Subclasses relating to scale or indicia reading should be particularly noted. Photocell circuits and apparatus are elsewhere. Photo-sensitive discharge devices are classified elsewhere. Mechanical scales and gauges which may be part of optical measuring systems are elsewhere. Mechanical indicators which may be part of optical measuring systems classified elsewhere. Electrical indicating and measuring devices which may be part of optical measuring systems are classified elsewhere. (See References to Other Classes, below, for class/subclass references to these art areas.)

SECTION III - SUBCLASS REFERENCES TO THE CURRENT CLASS

SEE OR SEARCH THIS CLASS, SUBCLASS:

SECTION IV - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

SECTION V - GLOSSARY

DIFFRACTION

The bending of a light ray in passing the edge formed by contiguous opaque and transparent edges.

DIFFUSE

Pertaining to the scattering or random deviation of transmitted or reflected light.

ELECTROPHORESIS

The effect in which charged particles suspended in a liquid are moved under the influence of an electrostatic field.

FIDUCIAL

A reference direction formed as by a light ray, level, compass, or scale from which another direction is measured or compared.

LIGHT, VISIBLE LIGHT

Visible light is radiation, which stimulates the optical receptors of the eye, and has a wavelength from 3850 to 7600 Angstrom units. The term light in these definitions refers to radiation in the above mentioned range, and when qualified by the terms ultraviolet and infrared refers to the corresponding radiation ranges adjacent the visible range.

MEASURING-TESTING

Measuring usually involves a more precise and quantitative determination of the characteristic or property in question. Testing may be a mere indication of the presence or absence of the characteristic or property, and may involve only a mere inspection or viewing of the phenomenon or specimen. It should be recognized that the two terms overlap to some extent in meaning.

MENSURATION

Measurement of lengths, areas, or volumes.

MONOCHROMATOR

An instrument for producing a narrow band of the spectrum by dispersing a radiation beam into its components or colors, and isolating the narrow band desired as by passing the components or colors through a narrow slit.

OPTICAL ELEMENT

A structure which performs a basic optical function. See Class 359 for a more specific definition.

OPTICAL SYSTEM

A combination of two or more similar or diverse optical elements which are optically related, or an optical element combined with nonoptical structure where the overall function performed is optical in nature. The optical systems in this class are for measuring or testing purposes.

OPTICS, OPTICAL

The science of light and vision and the construction of optical instruments.

REFLECTION

The return of light striking a surface back into the medium from which it came.

REFRACTION

The deviation of light which results when a ray of light passes obliquely from a medium of one density to a medium of another density.

SPECTRUM

The band of colors produced by separating white light into its component frequencies. The term also denotes radiation arrayed over a frequency range where the frequency of the radiation continuously increases or decreases over the range.

SUBCLASSES

2	CONTOUR PLOTTING
	This subclass is indented under the class definition.  Subject matter including structure responsive to two stereoscopic images as photographed or otherwise viewed at spaced points over a surface (usually of the earth) and furnishing a contour plot of the surface based on the distinctions in these images. (1) Note. The subject matter of this subclass usually involves a photodetecting apparatus such as a photocell system which scans or otherwise responds to the stereoscopic images or records, together with apparatus to compare the photocell outputs to operate some form of indicator such as a recorder. If the indication is by a scriber, classification is in Class 33; and if the output is an error signal as for alignment purposes classification is in Class 250, especially subclass 558. SEE OR SEARCH THIS CLASS, SUBCLASS: 138, for general alignment inspection. SEE OR SEARCH CLASS: 33,  Geometrical Instruments,   subclasses 20.1+ for sight line controlled geometrical scribers. 250,  Radiant Energy,   subclass 220 for photocell systems with plural photocells responsive to plural related images where the measuring is lacking. 348,  Television,   subclass 26 for television systems including means to generate contours based on features in the scene viewed. 353,  Optics: Image Projectors,   subclass 5 for projection involving mapping or aerial photograph rectifying. 359,  Optical: Systems and Elements,   subclass 470 for stereoviewers with compensation for camera positions, as of the plotting or mapping type.

3	RANGE OR REMOTE DISTANCE FINDING:
	This subclass is indented under the class definition.  Subject matter comprising instruments to measure the distance between an observer and a remote point or to measure the distance between two points remote from the observer. (1) Note. Height is a distance that may be measured. SEE OR SEARCH THIS CLASS, SUBCLASS: 496, for interferometric dimensional measurement of small structure or spaces. SEE OR SEARCH CLASS: 235,  Registers,   subclass 414 for means to calculate the range of a target and not employing a particular sighting means. 348,  Television,   subclasses 135+ for television systems utilized to determine range. 396,  Photography,   subclasses 89+ for range finders which operate in conjunction with camera structure.

3.01	Triangulation ranging to a point with one projected beam:
	This subclass is indented under subclass 3.  Subject matter including the following: (a) the distance to any single remote target point is determined in accordance with the principles of triangulation; (b) the target may include several points requiring more than one beamed measurement; and (c) a light beam or its reflection from the target point is oriented and projected to form at least one side of a triangle. (1) Note. Triangulation involves, for example, establishing a triangle where one side (i.e., the base) and the angles, which the two other sides form with the base, are determined. (2) Note. This subclass does not necessarily require the use of a photodetector, but requires a projected beam. (3) Note. This subclass includes, for example, apparatus that utilizes together a nonfixed axial source and a nonfixed axial line of sight for the sensing that is not found elsewhere, but that still requires only a single source for each point. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.09, where scanning is required to achieve angular measurement to a single point. 3.12, for photodetection remote from at least two source locations that are transmitting beams to be received by a photodetector. 9+, for triangulation with no projected beam and no photodetection. 625, for distance measurement to define the dimensions of an adjacent, as opposed to remote, article that may involve triangulation to any one point. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclass 201.6 for triangulation used to establish distance-related focus of the source onto a triangulating photodetector. 342,  Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation),   for the use of similar circuitry not requiring the same wavelength or radiation distinctions. 367,  Communications, Electrical: Acoustic Wave Systems and Devices,   for the use of similar circuitry not requiring the same wavelength or radiation distinctions. 396,  Photography,   subclasses 89+ where triangulation may be employed in the focus of a separate photographic camera.

3.02	Using photodetection with a fixed axial line of sight:
	This subclass is indented under subclass 3.01.  Subject matter that determines an angle of the triangle with respect to a known base line by establishing a fixed viewing direction and field of view for a photodetector to generate an electrical signal upon the coincidence of the target along a photodetector"s line of sight. (1) Note. This subclass would include apparatus that utilizes a moving detector with respect to a fixed optical viewing axis to determine the direction of light from a targeted source.

3.03	Using a source beam with a fixed axial direction or plane:
	This subclass is indented under subclass 3.01.  Subject matter that includes a beam or plane of light from the target that has a fixed angular orientation with respect to a baseline to establish an angle of the triangle. (1) Note. The use of a photodetector is not required for this subclass, but the use of a vidicon-type detector is found here. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.05, for a system that includes a moving optical axis in the receiver optics and a fixed detector.

3.04	With a single staring photodetector having one element:
	This subclass is indented under subclass 3.03.  Subject matter wherein a detector produces an electrical signal related to the angular position of the source based on the instantaneous output of or differential output across a single detecting element that is not subdivided for its operation. (1) Note. A one-element photodetector may consist of a lateral effect or photoresistive element. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.03, for vidicon-type detection. 3.06+, for use of detectors that define the position of incidence of received light by the difference in the outputs of more than two detector elements (e.g., at least three separate photodetectors).

3.05	Having moving receiver optics:
	This subclass is indented under subclass 3.04.  Subject matter wherein an image of the source is moved with respect to the detector"s axial line of sight to achieve an effective movement of the photodetector"s angular field of view across the source. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.02, for systems that may include a moving detector element with respect to a fixed optical line of sight.

3.06	With a single photodetector having multiple elements:
	This subclass is indented under subclass 3.03.  Subject matter wherein a detector produces an electrical signal related to the angular position of the source based on the output of a particularly positioned one of an array of at least three subelements in the focused field of view of a single detector structure. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.03, for vidicon-type detection. 3.07, for CCD-type multi-element detectors that are electronically scanned. 3.08, for two separated detectors that are paired.

3.07	Having electronic scanning of the photodetector:
	This subclass is indented under subclass 3.06.  Subject matter that includes electronic regular sampling through time of the elements of the detector array in order to determine the position or angle associated with a particular element illuminated by the target. (1) Note. This subclass includes, for example, CCD-type detectors. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.03, for vidicon-type detection.

3.08	With at least one paired set of staring photodetectors:
	This subclass is indented under subclass 3.03.  Subject matter wherein any two separated detectors produce electrical signals related to two angular positions detected from the single source. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.06, for a single detector subdivided into at least three subelements.

3.09	Requiring scanning of a source beam:
	This subclass is indented under subclass 3.01.  Subject matter wherein the source comprises a beam of light that is moved at some angular rate that can be detected and associated with any one target"s angular position. (1) Note. The target may be at the source position or reflected by the source, but scanning is required to generate the angular information. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.02, for moved but not necessarily spatially scanned sources that define a target with respect to a fixed axial line of sight of a photodetector.

3.1	Triangulation ranging to a point with two or more projected beams:
	This subclass is indented under subclass 3.  Subject matter wherein a target distance is determined in accordance with the principles of triangulation, and two light beams, separated by a known baseline distance, are oriented and projected to define the other two legs of the triangle. (1) Note. The two beams may be scanned over angularly related time across the target or moved at least once to orient their coincidence on the target. (2) Note. Triangulation involves, for example, establishing a triangle where one side (i.e., the base) and the angles, which the two other sides form with the base, are determined. (3) Note. This subclass does not necessarily require the use of a photodetector, but requires projected beams. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.09, where scanning is required to achieve angular measurement to a single point. 3.12+, for photodetection remote from at least two source locations transmitting beams to be received by a photodetector. 9+, for triangulation with no projected beam and no photodetection. 625, for distance measurement to define the dimensions of an adjacent, as opposed to remote, article that may involve triangulation to any one point. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclass 201.6 for triangulation used to establish distance-related focus of the source onto a triangulating photodetector. 342,  Communications: Directive Radio Wave Systems and Devices (e.g., Radar,   Radio Navigation) for the use of similar circuitry not requiring the same wavelength or radiation distinctions. 367,  Communications, Electrical: Acoustic Wave Systems and Devices,   for the use of similar circuitry not requiring the same wavelength or radiation distinctions. 396,  Photography,   subclasses 89+ where triangulation may be employed in the focus of a separate photographic camera.

3.11	Using photodetection at the source station(s):
	This subclass is indented under subclass 3.1.  Subject matter wherein an electrical signal is generated based on the reflection of the two beams from the target back to the plane, platform, or station(s) that supports the beams and the photodetector.

3.12	Using photodetection remote from the source station(s):
	This subclass is indented under subclass 3.1.  Subject matter wherein an electrical signal is generated based on the incidence of the two sources onto a photodetector that is not located on the same plane, platform, or station(s) as the two sources. (1) Note. The detector may be located at the target to receive direct unreflected directional beams of illumination from the sources.

3.13	Triangulation ranging with photodetection, but with no projected beam:
	This subclass is indented under subclass 3.  Subject matter wherein the distance to any single remote target point is determined in accordance with the principles of triangulation, wherein at least one passive image of a target point (which may be formed by arbitrary target point illumination) forms at least one side of a triangle. (1) Note. Triangulation involves, for example, establishing a triangle where one side (i.e., the base) and the angles, which the two other sides form with the base, are determined. (2) Note. The target point may be an active omnidirectional beacon source or may be actively illuminated where the active beam does not form one side of the triangle measured. (3) Note. Sequential views of a moving target with a known speed may comprise the target. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.12, for photodetection remote from at least two source locations transmitting directed beams to be received by a photodetector. 9+, for triangulation with no projected beam and no photodetection. 372+, for distance measurement to define the dimensions of an adjacent, as opposed to remote, article that may involve triangulation to any one point. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclass 201.6 for triangulation used to establish distance-related focus of the source onto a triangulating photodetector. 342,  Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation),   for the use of similar circuitry not requiring the same wavelength or radiation distinctions. 367,  Communications, Electrical: Acoustic Wave Systems and Devices,   for the use of similar circuitry not requiring the same wavelength or radiation distinctions. 396,  Photography,   subclasses 89+ where triangulation may be employed in the focus of a separate photographic camera.

3.14	Using at least a pair of viewing axes:
	This subclass is indented under subclass 3.13.  Subject matter which includes two optical axes relating to the target directed to at least two photodetectors or detector arrays in the generation of a pair of electrical signals related to the triangle that defines the distance to the target. (1) Note. The detector(s) may be mono- or multi-element, and further scanned or staring. (2) Note. This subclass includes passive image correlation of two images from a single target source in establishing two angles to the target. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.08, for a pair of staring mono- or multi-element detectors used where a single source maintains a fixed axial direction. 3.15, for image correlation where a photodetector views images of a target and where one of the images is established along a fixed line of sight. 4.04, for split-image separation detection of "focus" quality where there is no baseline separation between the separate image viewing axes as here in subclass 3.14. SEE OR SEARCH CLASS: 348,  Television,   subclass 139 for triangulation of range derived from two or more picture images generated and compared based on their baseline separation.

3.15	With one viewing axis fixed:
	This subclass is indented under subclass 3.14.  Subject matter wherein one optical axis that views the target is fixed relative to the other one of the pair of viewing axes.

3.16	With moving optical elements in all viewing axes:
	This subclass is indented under subclass 3.14.  Subject matter that includes movement of each viewing axis in order to achieve measurement of the target point.

4.01	With photodetection:
	This subclass is indented under subclass 3.  Subject matter that includes the generation of an electrical signal in response to light associated with the distance being measured. (1) Note. This subclass includes first any apparatus or method that includes a generic capability applicable to any one of pulse, phase, or frequency ranging systems. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.01+, for a system that involves triangulation, even though that term is not mentioned, but is evidenced by a baseline or trigonometric technique and contains either photodetection and/or the use of a projected light beam. 9+, for a system that uses neither a pro­ jected beam nor photodetection. 625, for distance measurement to define the dimensions of an adjacent, as opposed to remote, article that may involve similar ranging techniques to any one point. SEE OR SEARCH CLASS: 342,  Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation),   for the use of similar circuitry not requiring the same wavelength or radiation distinctions. 367,  Communications, Electrical: Acoustic Wave Systems and Devices,   for the use of similar circuitry not requiring the same wavelength or radiation distinctions.

4.02	Of a simulation or test:
	This subclass is indented under subclass 4.01.  Subject matter that includes a predefined range path for the light used to measure range in order to calibrate or test a range finder. (1) Note. The simulation in this subclass is not considered the same as the alternate reference path used in subclasses 5.12 and 5.13 used during the regular operation of those range finders. SEE OR SEARCH THIS CLASS, SUBCLASS: 72+, for other optical tests not specifically dedicated to range or distance finders.

4.03	Of focused image size or dimensions:
	This subclass is indented under subclass 4.01.  Subject matter that includes a determination of the distance of or to an observed object by the relative focused size of the object or dimensional spread of reference points on the focal plane of the photodetector with respect to a calibrated size and corresponding distance. (1) Note. The image size must be derived from a focused image as opposed to a blur circle size. SEE OR SEARCH THIS CLASS, SUBCLASS: 4.04, for blur circle size or edge detection. 21, for the same, but without photodetection. SEE OR SEARCH CLASS: 348,  Television,   subclass 140 where a picture image signal is analyzed for size.

4.04	Of degree of defocus:
	This subclass is indented under subclass 4.01.  Subject matter that includes a determination of the distance of a remote point or observed object by the degree of image focus through relative characteristics of in-and-out-of-focus intensity, blur circle size, lateral split image displacement, etc., of an image generated at some fixed location from focusing optics along its optical axis relative to the same characteristic under a focused condition at the same location along the optical axis. SEE OR SEARCH THIS CLASS, SUBCLASS: 3.14, for split images of a single object directed to two detectors separated by a baseline, unlike split-image focus detection here in subclass 4.04 where there is no baseline separation. 4.03, for a focused image feature measurement(s). 4.05, for mechanically searching for the focal point based on the same or other characteristics as in subclass 4.04. 22, for split images without photodetection.

4.05	Of focal point search:
	This subclass is indented under subclass 4.01.  Subject matter that includes a way to mechanically, or otherwise, sample the "image" along the optical axis of a fixed focus lens or scan the focus of a transmitted beam to determine the point of maximum focus of the image or reflection of the source which is proportional to the distance to the targeted remote point. SEE OR SEARCH THIS CLASS, SUBCLASS: 4.04, for determining range based on the focus characteristics of an image at some fixed point from the focusing lens.

4.06	Of differential amplitude at two source or detector distances:
	This subclass is indented under subclass 4.01.  Subject matter that includes either two sources at different distances from a target alternately illuminating the target at the remote point that a fixed detector views or includes two detectors at different distances receiving focused images of the target illuminated by a single source from which distance is determined based on the relative intensities detected.

4.07	Of intensity proportional to distance:
	This subclass is indented under subclass 4.01.  Subject matter that includes a measure of the relative intensity of the received focused target image from which distance may be determined by the fact that intensity varies by the inverse square of the distance or the like.

4.08	Of height relative to a light plane:
	This subclass is indented under subclass 4.01.  Subject matter that includes some apparatus between two remote points being measured that defines the height between the ground and a detector or reflector moved to intersect a light beam or beam plane that may be scanned or fanned. (1) Note. The apparatus may define a path for the light beam to traverse from the mirror intersecting the plane to the ground.

4.09	Of light interference fringes:
	This subclass is indented under subclass 4.01.  Subject matter wherein the photodetection is in response to an interference pattern formed by the interaction of coherent light waves which relate to range by a fringe pattern or fringe count. SEE OR SEARCH THIS CLASS, SUBCLASS: 5.09, for a system that detects frequency of modulation to determine range where the beat frequency of a mixed or compared beam is not directly related to a coherent interference fringe count. 5.11, for phase change counting between known frequencies of modulation that are unrelated to coherent carrier mixing in the production of fringes. 5.15, for a system that demodulates a return beam by coherent or incoherent mixing in order to shift the return to a different IF operating frequency unrelated to counting of fringes. 28.5, for a system where frequency is detected from the mixing of coherent waves that produce a moving, interference pattern or just a difference frequency, which is related to velocity.

4.1	Having different frequency sources:
	This subclass is indented under subclass 4.09.  Subject matter that includes at least two light beams from the same or different sources, but which have different frequencies.

5.01	Of pulse transit time:
	This subclass is indented under subclass 4.01.  Subject matter including means for measuring the time delay of a discrete light pulse in its time of flight (transit time) from an observing station to a remote point and back to the observing station.

5.02	Having return coincide with swept display or detector:
	This subclass is indented under subclass 5.01.  Subject matter wherein the return pulse"s reception time is related to transit time by reference to where it appears in time on a calibrated sweep of a display screen, detector, or film which begins a sweep at the instant of transmission.

5.03	Having one or more return pulse gates or windows:
	This subclass is indented under subclass 5.01.  Subject matter including means at the receiver for accepting return signals to be processed if they occur during specified (gate or window) periods after the transmission of a light pulse.

5.04	Including a displayed image:
	This subclass is indented under subclass 5.03.  Subject matter wherein the return pulse includes image data of a reflecting object at the remote point and is displayed as at least a two-dimensional image that does not include reflection signals outside the gate period. SEE OR SEARCH CLASS: 348,  Television,   subclass 31 for backscatter reduction of an image that may involve range gating, but does not involve range indicating.

5.05	Having pulse transmission trigger significance:
	This subclass is indented under subclass 5.01.  Subject matter including details of the manner in which the transmitted pulse instant is determined for measuring the transit time of the light pulse.

5.06	Including optical pick-off of transmission start:
	This subclass is indented under subclass 5.05.  Subject matter wherein the instant of pulse transmission is determined by optically detecting the transmission pulse in order to begin measuring the transit time.

5.07	With specific counter type timing of returns:
	This subclass is indented under subclass 5.06.  Subject matter including an electronic element that counts timing pulses associated with travel of the optical pulse to and from the target.

5.08	Including specific counter type timing of returns:
	This subclass is indented under subclass 5.05.  Subject matter including an electronic element that counts timing pulses associated with travel of the optical pulse to and from the target. (1) Note. This subclass includes electrical initiation of the counter controlled independently of the optical pulse itself.

5.09	Of frequency difference:
	This subclass is indented under subclass 4.01.  Subject matter that either sends a defined frequency beam or frequency modulates an outgoing pulse or continuous wave optical beam in order to compare the detected return frequency to the transmitted frequency for determining range calibrated frequency differences. SEE OR SEARCH THIS CLASS, SUBCLASS: 4.09+, where frequency is detected from the mixing of coherent waves that produce an interference pattern, which includes moving or static fringes which are counted. 5.15, where optical demodulation by heterodyning or homodyning is used to reduce the processed signal frequency. 28.5, where frequency is detected from the mixing of coherent waves that produce a moving interference pattern or just a difference frequency, which is related to velocity.

5.1	Of CW phase delay:
	This subclass is indented under subclass 4.01.  Subject matter that incorporates a continuous wave (CW) of modulated or unmodulated optical signal that is transmitted to and reflected from a target, such that the relative phase position of the returned wave is compared to the phase of the transmitted wave in order to determine the distance-proportional transit time to and from the target. (1) Note. Phase nulling techniques are included in this subclass.

5.11	Having multiple carrier or modulation frequencies:
	This subclass is indented under subclass 5.1.  Subject matter including more than one frequency of modulation or carrier frequency for the transmitted optical signal to further define the distance-proportional phases comparison.

5.12	Including an alternating reference path:
	This subclass is indented under subclass 5.11.  Subject matter that incorporates a path of known distance through which the transmitted signal is alternately sent in order to phase calibrate the receiver circuity for the received measuring signal from the target.

5.13	Having an alternating reference path:
	This subclass is indented under subclass 5.1.  Subject matter that incorporates a path of known distance through which the transmitted signal is alternately sent in order to phase calibrate the receiver circuity for the received measuring signal from the target.

5.14	Having polarization discrimination:
	This subclass is indented under subclass 5.1.  Subject matter that incorporates polarized optical elements in the optical path.

5.15	Having specific IF mixing of returns:
	This subclass is indented under subclass 5.1.  Subject matter that incorporates demodulation by optically or electrically heterodyning the received signals to an intermediate frequency (IF) for further processing. SEE OR SEARCH THIS CLASS, SUBCLASS: 4.09+, for systems that mix the return with another beam to produce a fringe pattern to be counted and frequency analyzed as a direct measurement of range. 5.09, for systems that detect frequency of modulation to determine range where the beat frequency of a mixed or compared beam is not directly related to a coherent interference fringe count or to CW phase delay.

6	Instrument condition testing or indicating
	This subclass is indented under subclass 3.  Subject matter comprising means for testing or indicating the condition of the range or height finder with regard to its adjustment, alignment, or calibration. SEE OR SEARCH THIS CLASS, SUBCLASS: 124, for lens or reflective image former testing generally.

7	Periscope or offset type
	This subclass is indented under subclass 3.  Subject matter wherein the instrument has two axis which are offset from each other in a direction perpendicular to the base line so that the device may function as a periscope. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 540+ for periscopes, per se.

8	With view finder
	This subclass is indented under subclass 3.  Subject matter wherein the range or height finder is combined with a view finder. (1) Note. Where the operation of the range finder is coordinated with the operation of some other element of the camera (usually the objective lens) classification is not here but in Class 396, subclasses 148+. SEE OR SEARCH CLASS: 396,  Photography,   subclasses 148+ for camera structure combined with a rangefinder and viewfinder; see also (1) Note above.

9	Base line instrument (i.e., base is a part of instrument)
	This subclass is indented under subclass 3.  Subject matter wherein the range or height finder includes a base line as a part of the instrument with plural lines of sight directed from the extremeties of the base line to the point whose range is to be measured, at least one of the lines of sight being deviated.

10	With filter or light valve
	This subclass is indented under subclass 9.  Subject matter wherein filters or light valves are employed to aid the eye as in determining coincidence of the right and left images. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 227+ for diaphragms and shutters, and subclasses 885+ for filters of the color and neutral density type.

11	Range finder combined with height finder
	This subclass is indented under subclass 9.  Subject matter wherein the range finder is combined with means to determine the height of the object whose range has been determined.

12	Stereoscopic
	This subclass is indented under subclass 9.  Subject matter wherein the observer sees the field of view in three dimensions, the range being determined by comparing the depth of the object whose range is to be measured with the apparent depth of a mark or marks superimposed upon the field of view. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 462+ for stereoscopic systems generally.

13	Ortho-pseudo type
	This subclass is indented under subclass 12.  Subject matter where the observer sees an image in true perspective and also one in reverse perspective.

14	Stationary measuring marks
	This subclass is indented under subclass 12.  Subject matter where the measuring mark or marks are stationary.

15	Length of base line variable
	This subclass is indented under subclass 9.  Subject matter wherein the range measurement is made by varying the length of the base line.

16	Image displaced by moving refracting element
	This subclass is indented under subclass 9.  Subject matter wherein the range measurement is made by deviating one of the lines of sight by means of an adjustable refracting element.

17	Image displaced by rotating reflecting element
	This subclass is indented under subclass 9.  Subject matter wherein the range measurement is made by deviating one of lines of sight by means of the rotation of a reflecting element.

18	With mounting, supporting, adjusting, or folding structure
	This subclass is indented under subclass 9.  Subject matter comprising structural details including means for mounting, supporting or adjusting the range finder or its components. SEE OR SEARCH THIS CLASS, SUBCLASS: 6, for testing the alignment or calibration of the instrument.

19	Prism structure for determining coincidence
	This subclass is indented under subclass 9.  Subject matter including prism structure for displacing relative to each other the two images of a coincidence type range finder. (1) Note. Such prism structure is appropriately classified here as a pertinent subcombination even though no other range finder structure is recited.

20	External basis type
	This subclass is indented under subclass 3.  Subject matter wherein the complete measurement requires the knowledge of some distance or interval external to the measuring instrument. SEE OR SEARCH CLASS: 33,  Geometrical Instruments,   appropriate subclasses, particularly subclasses 262 , 276, and 284, for similar subject matter with no significant optical feature.

21	Object size or distance known
	This subclass is indented under subclass 20.  Subject matter where there is an interval of known size (e.g., height of an object) at a remote point, the distance to which point is to be determined; or where the distance to a remote point is known and the size of some interval at the remote point is to be determined.

22	With displaced images
	This subclass is indented under subclass 21.  Subject matter where the instrument provides two displaced images of the same object for viewing by the observer.

23	MOTION STOPPING (E.G., STROBOSCOPES)
	This subclass is indented under the class definition.  Subject matter comprising means whereby the relationship between periodic changes in light intensity or direction and the motion of a body are utilized in observing the body or performing some measurement with regard to the body or some means controlling the light source. (1) Note. Where a specific test is provided for in another class, classification is in that class even though the subject matter may include a stroboscope. See Search Class notes below. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 1.56 for timing apparatus for watches, camera shutters and the like which may utilize stroboscopic principles. 315,  Electric Lamp and Discharge Devices: Systems,   appropriate subclasses for electric lamp and discharge device systems in general. 324,  Electricity: Measuring and Testing,   subclass 75 for calibration of electric meters using stroboscopic principles, and subclasses 76.11+ for measuring electric properties using stroboscopes.

24	Periodically moving reflecting or refracting element
	This subclass is indented under subclass 23.  Subject matter including reflecting or refracting means which are moved periodically to vary the direction of a light beam. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 196.1 through 226.3for scanning means in general which use a periodically moving reflecting or refracting element.

25	Periodically moving light interrupting element
	This subclass is indented under subclass 23.  Subject matter wherein the periodic motion of an element containing alternate opaque and transparent areas is used to interrupt a light source. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 227+ for light valves utilzing an opaque element movable through a light path.

26	Vibrating or oscillating element
	This subclass is indented under subclass 25.  Subject matter where the opaque element vibrates or oscillates.

27	VELOCITY OR VELOCITY/HEIGHT MEASURING
	This subclass is indented under the class definition.  Subject matter including means to measure the velocity or the velocity to altitude ratio of a vehicle by sighting from the vehicle on a remote object, or including means to measure the velocity or the velocity to altitude ratio of a moving object remote from an observer by sighting on the object. (1) Note. The vehicle may be a surface vehicle or an aircraft. The term "sighting" includes aiming an optical instrument with a photocell. This subject matter includes timing the passage of a sighted object over grids. SEE OR SEARCH THIS CLASS, SUBCLASS: 459, for interferometric measurement of angular velocity. SEE OR SEARCH CLASS: 235,  Registers,   subclass 413 for means to calculate the velocity of an object and not employing a particular sighting means.

28	With light detector (e.g., photocell)
	This subclass is indented under subclass 27.  Subject matter wherein the measuring system includes means responsive to the received light. SEE OR SEARCH THIS CLASS, SUBCLASS: 3+, for range or height finders with light detectors. 139.01+, for devices measuring the angle with respect to a remote point having specified applications with photodetection. 141.1+, for devices measuring the apex of an angle at a photodetection station with respect to a remote point. 152.1+, for devices measuring the apex of an angle at a point remote from a photodetection station. SEE OR SEARCH CLASS: 343,  Communication: Radio Wave,   subclass 8 for systems for measuring velocity by means of reflected radio wave energy.

28.5	Of light interference (e.g., interferometer):
	This subclass is indented under subclass 28.  Subject matter wherein the detection means is responsive to an interference pattern formed by the interaction of coherent light waves. (1) Note. This subclass includes heterodyne interferometers which measure a doppler-shifted beam reflected from a moving object. SEE OR SEARCH THIS CLASS, SUBCLASS: 4.09, and 4.1, for light interference measurement of displacement or distance over large distances. 35.5, for material strain analysis by light interference measurement. 450, for light interference measuring and testing, per se. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 71.3 for vibration sensing with a light beam indicator.

29	OPTICAL ELEMENT OR RETICLE RESPONDS TO RELATIVE VELOCITY OF REMOTE OBJECT
	This subclass is indented under the class definition.  Subject matter comprising means whereby a device for determining a line of sight relative to a remote point includes an optical element or reticle which is moved relative to the device in accordance with the relative velocities of the device and remote point. (1) Note. This subclass includes in general sighting devices containing optical elements which move relative to the device as a whole for the purpose of tracking a relatively moving object and also optical elements or reticles which are moved in accordance with information obtained by tracking the object by means of moving the sighting device as a unit. SEE OR SEARCH THIS CLASS, SUBCLASS: 27, for optical devices which actually measure velocity.

30	CRYSTAL OR GEM EXAMINATION
	This subclass is indented under the class definition.  Subject matter including a support for a crystal or gem for examination by visible light, a light source passing light through or reflecting light from the crystal or gem and usually structure to view, mark, or locate the light patterns correlated to some condition of the crystal or gem. (1) Note. Included in this subclass are apparatus and method claims which include nominal cutting or etching structure or steps to prepare the crystal for examination in addition to the claimed test. (2) Note. The optical testing of piezoelectric and semiconductor crystals are included in this subclass. SEE OR SEARCH THIS CLASS, SUBCLASS: 36, for sample preparation wherein the novelty is in the preparation of the sample for an optical test and not provided for elsewhere. 72, for an optical test combined with another are device and not provided for elsewhere. SEE OR SEARCH CLASS: 29,  Metal Working,   subclass 25.35 for piezoelectric device making methods, which include cutting and etching steps. 125,  Stone Working,   subclasses 12 and 13.01 for apparatus and methods for cutting crystals which include the step of first examining optically and marking the crystal for axis orientation. Also, see subclass 35 for work supports for cutting the crystal. 156,  Adhesive Bonding and Miscellaneous Chemical Manufacture,   subclasses 625+ for methods including a chemical etching step. 378,  X-Ray or Gamma Ray Systems or Devices,   subclasses 73+ for methods and apparatus for X-ray analysis of crystals which may include a support for the crystal.

31	Axes determination
	This subclass is indented under subclass 30.  Subject matter wherein the properties of crystals or gems are examined for one of the three principle axis of the crystal, the left or right handedness of the crystal, the polarity or the crystal faces, or twinning, if present, in the crystal. SEE OR SEARCH CLASS: 216,  Etching a Substrate: Processes,   for the etching of a crystal or gem.

32	MATERIAL STRAIN ANALYSIS
	This subclass is indented under the class definition.  Subject matter for examining an article or material by noting the effect of the strain in the stressed article on light associated with the article or material. (1) Note. The light may be passed through or reflected from the article or material, or may be modified by changes in the contour or the position of markings thereon. The modification of the light may be in intensity, direction, polarization, color, or interference patterns produced thereby. (2) Note. Stress strain measuring generally is provided for elsewhere (see the Search Class notes below). However, where the changes in the material tested operate to modify the characteristics of the light associated with the test, absent intentional loading of the specimen, classification is in this Class 356. SEE OR SEARCH CLASS: 33,  Geometrical Instruments,   subclass 125 for extensiometers. See the (2) note of this subclass. 73,  Measuring and Testing,   subclasses 763+ for testing the stress or strain of material, particularly subclass 800 for optical stress analysis with intentional loading of the specimen, and subclasses 862+ for dynamometers which are not provided for elsewhere and which do not involve the modification of the associated light. See also (2) Note above.

33	With polarized light
	This subclass is indented under subclass 32.  Subject matter wherein the light utilized in the examination or analysis is polarized light, or is polarized as a result of the examination or analysis. (1) Note. Class 359, subclasses 240+ and 483 provides for polarizing structure generally whose light polarizing properties are modified by mechanical stress; while the subject matter of this subclass is restricted to the measuring or analyzing of the strain in the stressed article or material from the effect of the strain on polarized light or from the polarizing effect of light. (2) Note. This Class 356 provides for stress-strain determinations in articles or materials where the light is directly or indirectly associated with the article or material stressed as by direct reflection from or transmission through the articles or materials, and for transmissions of the light through detectors attached to articles or materials which are naturally or forced by stress to be light birefringent as a result of the strain on the articles or materials; while Class 73, subclasses 760+, provides for stress-strain determinations generally. SEE OR SEARCH THIS CLASS, SUBCLASS: 30, for crystal or gem examination wherein polarized light testing may be involved. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 133 and 763+ for stress-strain testing apparatus and dynamometers generally where no polarized light is involved. See also (2) Note above.

34	Attached detector
	This subclass is indented under subclass 33.  Subject matter wherein the test apparatus utilized in examining articles or materials includes a detector which is naturally birefringent or forced by stress to be birefringent, and means to attach the detector to the articles or materials so that the strain placed on the articles or materials is imparted to the detector so that the modification of the light associated with the detector is indicative of the strain in the stressed article or material. SEE OR SEARCH THIS CLASS, SUBCLASS: 51, where infrared and ultraviolet light is involved in the test. 364, for polarized light examination apparatus which produces interference patterns created by the interaction of beams of polarized light. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 483+ for polarizing structure generally. See also (1) Note of subclass 33.

35	Sheet material
	This subclass is indented under subclass 33.  Subject matter wherein there is means to support transparent sheet material, statically or in motion, which exhibits birefringent properties naturally or when under strain, means to direct polarized light through the sheet material, and generally polarized light analyzing means to examine the sheet material. SEE OR SEARCH THIS CLASS, SUBCLASS: 429+, for monitoring of webs for optical properties or flaws.

35.5	By light interference detector (e.g., inter-ferometer):
	This subclass is indented under subclass 32.  Subject matter including means responsive to an interference pattern produced by the interaction of coherent light waves with the stressed article or material. SEE OR SEARCH THIS CLASS, SUBCLASS: 4.5, for light interference measurement of displacement or distance over large distances. 28.5, for light interference measurement of velocity. 450, for light interference measurement, per se.

36	WITH SAMPLE PREPARATION
	This subclass is indented under the class definition.  Subject matter involving preparation or conditioning of an article or substance or a sample of the article or substance to facilitate or enable the later optical test and in combination with such an optical test, wherein the preparation or conditioning is significant and is not provided for in any other class. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   particularly subclass 23 for gas analysis and 53.01+ for the testing of liquid or liquid suspension of solids, and subclass 421 for samplers and tollers for gases and liquids including closed conduit type samplers. 422,  Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   subclasses 50+ for analyticalcontrol apparatus and apparatus which use sorbents or in which chemical reactions are produced. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 1+ for processes involving analytical control and use of sorbents or chemical reactions.

37	Condensation nuclei detector
	This subclass is indented under subclass 36.  Subject matter wherein moisture or other liquids are deposited on particles to enlarge them or optically modify them (e.g., improve reflection) to facilitate optical study of the particles. (1) Note. Generally the apparatus includes pump structure to deliver a gas sample containing particles, expand the sample under a constant volume to obtain a supersaturated condition with respect to the gas, deliver the expanded gas sample to a chamber to optically test the gas with moisture precipitated as a result of the gas expansion on the particles present in the gas, and exhaust the sample from the apparatus. (2) Note. The particles examined include ionized particles and molecular types. SEE OR SEARCH THIS CLASS, SUBCLASS: 335+, for the determining of the size of particles by optical methods. 337+, for particle light scattering generally including the concentration or number of particles by statistical methods. 437+, for transmission tests through gases for the determination of the concentration of particles present in the gases generally and visual inspection equipment. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 28 for the determination of the amount of solid matter in the analysis of gases generally, subclass 29 for moisture content of gases, and subclass 421 for reciprocating and rotary samplers involving gases and liquids. 340,  Communications: Electrical,   subclasses 227 and 237 for methods and apparatus which may involve the detection of condensation nuclei, per se, or the use of condensation nuclei to detect the dew point of gases. 422,  Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   subclasses 50+ for analytical apparatus having a condensation nuclei detector. 436,  Chemistry: Analytical and Immunological Testing,   subclasses 1+ , for processes involving the testing of condensation nuclei for traces of chemical elements wherein a chemical reaction is precedent to an optical test to determine the presence or amount of the elements present.

38	Depositing particles on optical surface
	This subclass is indented under subclass 36.  Subject matter wherein the means to prepare or condition includes a movable member which serves as a support to receive successively samples of particulate material from a gaseous stream or from a pulverent supply of material, the member supporting the particulate matter for the optical test. SEE OR SEARCH THIS CLASS, SUBCLASS: 335, for the determination of the size of particles by optical procedures. 337+, for the determination of particle light scattering including polarization effects. 429+, for the monitoring of webs generally. 438+, for light transmission tests of dust or smoke. 625, for the mensuration of substances or articles by light tests generally. SEE OR SEARCH CLASS: 340,  Communications: Electrical,   subclasses 627+ for the testing of fluent or pulverized material in a gas or liquid wherein an electrical signal is involved.

39	BLOOD ANALYSIS
	This subclass is indented under the class definition.  Subject matter wherein a specimen of blood or tissue is tested in vitro (i.e., outside the body) for various conditions by means of visible light apparatus, and the blood testing apparatus is not elsewhere classified. SEE OR SEARCH THIS CLASS, SUBCLASS: 246, for fluid specimen containers. 335+, for the determination of particle size, or particle size and the number of particles for each size when determined by statistical methods. 337+, for the determination of the number of particles in a fluid medium by light scattering procedures using statistical methods. 441+, for the determination of the number of particles in a fluid medium by light absorption using statistical methods and the determination of turbidity of liquids generally. SEE OR SEARCH CLASS: 377,  Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems,   subclass 10 for particle counters with or without the sizing of the particles counted by arithmetical methods. 382,  Image Analysis,   subclasses 128+ , for an image analyzing system designed specifically for, or utilized in microscopic cell analysis or other biomedical applications, where there is significant claim recitation of an image analyzing system and no claim recitation of significant structure to an external art environment. 422,  Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   subclasses 44+ for apparatus for testing blood externally of a blooded animal 435,  Chemistry: Molecular Biology and Microbiology,   subclass 2 for processes and compositions for the maintenance of blood (cells) in a physiologically active state or for the in vitro separation or treatment of blood cells; and subclasses 4+ for processes measuring or testing involving enzymes or measuring or testing involving enzymes or micro-organisms (e.g., bacteria, protozoa, actinomycetales, cyanobacteria, fungi, animal cells, plant cells, or virus); and subclasses 287+ for claimed or solely disclosed as a Class 435 process. 436,  Chemistry: Analytical and Immunological Testing,   appropriate subclasses for processes and compositions for determining qualitatively or quantitatively the chemical property or composition of a sample and for in vitro antigen-antibody analysis or composition, especially subclasses 66+ for processes or compositions for testing for hemoglobin, myo-globin, or trace blood; subclass 68 for processes or compositions for determining gases in the blood, and subclass 70 for processes and compositions for determining sedimentaion rate or hematocrit. 600,  Surgery,   subclasses 310+ for diagnostic medical apparatus which may utilize visible light to test or inspect blood in vivo.

40	Hemoglobin concentration
	This subclass is indented under subclass 39.  Subject matter which includes visual and photoelectric apparatus to examine the specimen for the percentage of hemoglobin. SEE OR SEARCH THIS CLASS, SUBCLASS: 51, for infrared or ultraviolet testing of materials generally where optical methods are utilized. 300+, for spectroscopic apparatus. 402+, for colorimetric apparatus of the visual and photoelectric type. 441+, for liquid turbidity testing generally. 445+, for reflective material testing generally. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 53 for testing the settling rate of the liquid suspension of solids.

41	Oximeters
	This subclass is indented under subclass 40.  Subject matter to determine the percentage of oxyhemoglobin in the specimen which includes a transmissive or reflective optical tests. SEE OR SEARCH THIS CLASS, SUBCLASS: 42, for standards utilized in a comparison test with a blood sample. SEE OR SEARCH CLASS: 600,  Surgery,   subclasses 310+ for diagnostic apparatus and methods including subcombinations, for in vivo, i.e., directly measuring properties of the living body which may include an optical test. 604,  Surgery,   subclasses 20+ for subject matter relating to administration or removal of material from the body by means responsive to optical diagnostic means.

42	Standards
	This subclass is indented under subclass 40.  Subject matter wherein there is included generally means to support a light reflective or transmissive standard or a light emissive standard formed as part of the test apparatus whereby the standard is compared simultaneously side by side with the specimen either for equality of shade of color and light intensity or for intensity of light alone. SEE OR SEARCH THIS CLASS, SUBCLASS: 46, for light standards, per se. 243.1+, for optical standards generally. 403, for the merging of colors or patterns generally. 413, for colorimeters generally of the Duboscq type. 414+, for colorimeters testing colored liquids generally which utilize a solid or liquid transmissive standard, and including standard optical wedges, Nessler tubes and micro-colorimeters. 420, for a colored light source, per se, which may be utilized as standards. 421+, for reflective colored standards which include discs, drums, tapes or plates. 425, for the determination of color generally by light intensity comparison. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 831+ for prisms which may be used as standards. 422,  Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   appropriate subclasses, especially subclasses 50+ for laboratory devices or apparatus of quantitative or qualitative analysis involving either a physical or a chemical reaction, not elsewhere provided for.

43	OPTICAL PYROMETERS
	This subclass is indented under the class definition.  Subject matter for analyzing the light emitted from a body for properties such as intensity or color components as an indication of the temperature of the body. (1) Note. The body may be heated in turn by another mass which may be either a gas, liquid, or solid; and the purpose here would be to ultimately determine the temperature of such a mass by the determination of its heating effect on the body. (2) Note. Both temperature devices for metallurgical and photographic use are included herein when the indication is in a unit of temperature. SEE OR SEARCH THIS CLASS, SUBCLASS: 213, for photometry devices. 300+, for optical test devices which utilize a light dispersing system rather than filters to selectively detect various wavelengths of visible light. 402+, for shade or color optical test devices, and particularly subclass 404 for such test devices involving photography, and subclasses 416+ for such test devices which utilize one or more colored filters. SEE OR SEARCH CLASS: 219,  Electric Heating,   subclass 502 for the control of an electric heater by means of a light responsive temperature detector. 236,  Automatic Temperature and Humidity Regulation,   subclass 15 for the measurement of the temperature of a furnace for the control of the heating of the furnace. 250,  Radiant Energy,   subclass 226 for radiant energy detectors utilizing filters or dispersing means, and subclass 229 for light modulator detection systems. 266,  Metallurgical Apparatus,   subclasses 78+ and 99+, for metallurgical furnaces combined with temperature determination means. 374,  Thermal Measuring and Testing,   subclass 32 for measuring the total energy emitted from a source; and subclasses 121+ for subject matter similar to that in this subclass where the emitted radiation is not limited to light.

44	With sample engaging rod or tube
	This subclass is indented under subclass 43.  Subject matter wherein there is structure such as a rod or tube to contain and contact a heated solid or fluid or to be immersed into a heated fluid whereby there is a heat exchange from the heated solid or fluid, which causes the structure to emit light or the structure allows the light emitted from a heated solid or fluid to be directly transmitted to a detector which analyzes this light in terms of temperature. SEE OR SEARCH THIS CLASS, SUBCLASS: 216, for heat absorbing radiometers of the revolving vane type. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclass 227 for light conducting rods conducting light to a photocell. 374,  Thermal Measuring and Testing,   subclass 126 for a rod or tube with a particular radiating surface combined with a radiation thermometer; and subclass 131 for a radiation conducting rod or fiber bundle combined with a radiation thermometer.

45	Plural color responsive
	This subclass is indented under subclass 43.  Subject matter which includes means to selectively detect at least two different bands of visible radiation simultaneously or sequentially from an emission source, and means responsive to the detection means to indicate the color temperature of the emissive source. (1) Note. Where the indication of the test is not stated in the claims in terms of temperature, classification is in subclass 404 when photography is involved or in subclass 407 when plural colors are simultaneously tested, or in subclass 408 for sequential comparison tests of a sample and a standard. SEE OR SEARCH THIS CLASS, SUBCLASS: 405, for tristimulus test devices. 406, for shade or color tests involving three colors. 419, for devices which sequentially utilize plural color filters. SEE OR SEARCH CLASS: 374,  Thermal Measuring and Testing,   subclass 127 , for nonoptical radiation type pyrometers which may be responsive to purals ranges of electromagnetic radiation.

46	With incandescent standard
	This subclass is indented under subclass 43.  Subject matter including a standard incandescent source of radiation together with structure to compare or facilitate the comparison of the unknown light radiation from a hot body or other emissive source with the visible radiation emitted from the incandescent standard. (1) Note. Patents claiming electrical circuitry to cause current to flow through electric incandescent lamps which are light standards are placed here, whether the standard lamp is used for a temperature test or a light intensity test. SEE OR SEARCH THIS CLASS, SUBCLASS: 218+, for photoelectric photometers. 230+, for visual photometers utilizing a light standard. 243.1+, for standards generally. SEE OR SEARCH CLASS: 313,  Electric Lamp and Discharge Devices,   subclass 271 for support or spacing structure for incandescent filaments used for light emission, and subclass 315 for incandescent lamps.

47	Automatic intensity control
	This subclass is indented under subclass 46.  Subject matter which includes means to compare and control automatically the intensity of the illumination of the incandescent standard. (1) Note. Systems utilizing radiant energy detectors to balance by means of optical elements the detectors controlled by the intensity of light emitted by plural sources of light are elsewhere. Systems where the intensity of a light source is adjusted by optical means controlled by a radiant energy detector responsive to the light source intensity are also elsewhere classified. See the Search Class notes below. (2) Note. A system utilizing a radiant energy detector to control an electrical lamp by electrical means where no significant optical structure is in the path between the light source tested and the radiant energy detector of the system, and no indication relating to the light emitted by the lamp is claimed and the lamp is the ultimate load of the system is elsewhere. See the Search Class notes below. (3) Note. The testing of lamps, per se, to determine the lamp characteristics before actual use, including the intensity of light emitted per watt input is classified elsewhere (see the Search Class notes below). However, where the lamp is utilized in a testing environment of use for illumination or where temperature or intensity of light of some unknown source or other optical test is involved which includes a measurement or a subcombination not elsewhere provided, even though the measurement is of current or voltage, classification will be in Class 356. SEE OR SEARCH THIS CLASS, SUBCLASS: 130, for refractive tests which utilize a servo-controlled device to adjust the light intensity of a beam of light used in the test. 321+, for plural beam absorption spectro-photometers which have structure to adjust the light intensity of one of the beams by automatic means. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclass 204 takes systems utilizing radiant energy detectors to balance by means of optical elements the detectors controlled by the intensity of light emitted by plural sources of light; subclass 205 for systems where the intensity of a light source is adjusted by optical means controlled by a radiant energy detector responsive to the light source intensity. No indicator related to the optical properties of the light included in the claims should be classified there. See also (1) Note above. 315,  Electric Lamp and Discharge Devices: Systems,   subclasses 149+ will take a system utilizing a radiant energy detector to control an electrical lamp by electrical means where no significant optical structure is in the path between the light source tested and the radiant energy detector of the system, and no indication relating to the light emitted by the lamp is claimed and the lamp is the ultimate load of the system. subclass 151 for radiant energy systems responsive to a lamp to control the intensity of light from the lamp by electrical means; also see subclasses 129+. See (2) Note above. 318,  Electricity: Motive Power Systems,   subclasses 18+ for follow-up systems utilizing radiant energy which have as their ultimate purpose the control of an electric motor. 324,  Electricity: Measuring and Testing,   subclasses 403+ will take the testing of lamps, per se, to determine the lamp characteristics before actual use, including the intensity of light emitted per watt input. See the (3) Note above.

48	Modulating (e.g., flicker beam)
	This subclass is indented under subclass 46.  Subject matter wherein the means to compare or facilitate the comparison of the standard and unknown radiation includes means to modulate mechanically or optically the standard or the unknown radiation. (1) Note. The modulated unknown or standard radiation may include portions of other radiation. (2) Note. Color discrimination and optical attenuation means may be part of the combination claimed. SEE OR SEARCH THIS CLASS, SUBCLASS: 217, for modulation type photometers where temperature is not involved. 418, for shade or color tests where color and intensity of light is included and an incandescent standard may be involved but temperature is not involved and modulation of the light takes place. 425, for light intensity comparison of shade where temperature is not involved but modulation may be involved. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclasses 232+ for optical modulators or flickering beam photocell circuits of general usage. 374,  Thermal Measuring and Testing,   subclasses 121+ for radiation pyrometers which utilize modulating means.

49	Telescopic
	This subclass is indented under subclass 46.  Subject matter including a telescope for passing unknown visible radiation and having an objective and ocular lens system, and means to locate, physically or optically, the incandescent standard in the optical path of the lens system so that visible radiation of the standard and the unknown radiation may be viewed simultaneously. (1) Note. Herein are those telescopic pyrometers which attenuate the intensity of the light or the color of the unknown source or the standard by optical means. SEE OR SEARCH THIS CLASS, SUBCLASS: 46, for calibrated light standard systems, per se, used for comparison with unknown visible light for temperature, colorimetry or photometry purposes. 230, for photometers which visually compare light intensities by means of an incandescent standard. 364+, for tests which utilize polarized light for examination purposes where temperature is not involved. 404, for color or shade determination for photographic purposes where color temperature is not involved. 416+, for shade or color tests involving optical filters where temperature is not involved. 417, for flame detecting photometers not concerned with temperature which utilize color filters rather than dispersing or diffracting elements to separate the radiation into discrete colors. 425, for color determination by light intensity comparison where color temperature is not involved. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclass 738 for lens systems having light limiting or controlling means.

50	Current control
	This subclass is indented under subclass 49.  Subject matter wherein the incandescent standard is an electrically heated filament and means are provided to control the current through the filament. (1) Note. These instruments may include optical elements to change the color and intensity of the unknown radiation or the standard radiation. SEE OR SEARCH THIS CLASS, SUBCLASS: 46, for the electrical circuits, per se, which power the electrical incandescent standard. 231, for photometers which utilize an electrical incandescent lamp which includes means to vary filament current. SEE OR SEARCH CLASS: 315,  Electric Lamp and Discharge Devices: Systems,   subclasses 129+ for electrical circuits supplying current to a lamp, which is not an electrical test standard, which circuit includes an electrical indicator. 374,  Thermal Measuring and Testing,   subclass 129 for radiation pyrometers which include an electrically variable incandescent standard.

51	INFRARED AND ULTRAVIOLET
	This subclass is indented under the class definition.  Subject matter involving nonvisible radiation such as infrared and ultraviolet radiation not provided for elsewhere. (1) Note. The subject matter of this subclass relates to apparatus and methods similar to that provided for in the other subclasses of this class, i.e., subject matter of an optical nature as would be operative with visible radiation. However, in this subclass the operation has been extended to involve the nonvisible spectrum but in an optical manner, such as refraction and reflection in accordance with optical principles, and not provided for elsewhere, e.g., Class 374, subclasses 121+ for radiation thermometers. Class 250, especially in subclasses 336.1+ provides for apparatus with significant nonvisible radiation structure including measuring and testing of invisible radiation. Examples of significant nonvisible radiation structure for classification in Class 250 are: a source of invisible radiation such as infrared or ultraviolet, particular material operative only in the invisible radiation range, the application of the measuring or testing to subject matter or specimens responsive only to invisible radiation to carry out the measurement or test. It is emphasized that as between this Class 356 and Class 250 the general requirements for Class 356 must be also met for classification here. For example, photocell measuring circuits must claim the meter or indicator or the specimen holder for classification here. A lesser combination such as a photocell circuit would be classified in Class 250. See (1) Note under subclass 218. (2) Note. Where one claim to measuring and testing uses only visible light in the test and another claim to measuring and testing uses only invisible radiation, the original classification is in Class 356, appropriate subclass and cross-references in Class 250, appropriate subclass. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclasses 336.1+ for methods and apparatus including an electric signalling device for detecting infraviolet radiation and subclasses 472.1+ for nonelectric signalling methods and apparatus responsive to infrared or ultraviolet light. See also the (1) Note to this subclass. 374,  Thermal Measuring and Testing,   subclasses 121+ for the detection of infrared and visible light energy to determine the temperature of a body from which the radiation is thermally emitted. 378,  X-Ray or Gamma Systems or Devices,   appropriate subclasses for measuring and testing using X-rays.

52	EGG CANDLING
	This subclass is indented under the class definition.  Subject matter which involves light transmission through eggs, which light may be photoelectrically or visually detected to determine the fertility, freshness or other conditions of the eggs. (1) Note. Included in this subclass are all hand or bodily held devices used for candling eggs. (2) Note. The combination of candling of eggs and the incubation of the eggs is in Class 119, Animal Husbandry. However the heating of the eggs to perfect a candling operation is in Class 356, subclass 36. SEE OR SEARCH THIS CLASS, SUBCLASS: 432+, for tests involving light transmission tests through translucent and transparent articles. SEE OR SEARCH CLASS: 15,  Brushing, Scrubbing, and General Cleaning,   subclass 3.11 for machines to clean and sort eggs or screen out dirt from eggs. 53,  Package Making,   subclass 147 for the group forming of articles and the subsequent packaging of the articles in portable receptacles and subclass 167 for the combination of a visual test of an article and the filling of portable receptacles with the tested articles. 119,  Animal Husbandry,   subclass 6.8 for methods and apparatus for hatching eggs including the step of candling of eggs, and subclasses 311+ for incubators. 221,  Article Dispensing,   appropriate subclass for releasing articles one at a time from a supply apparatus.

53	Photoelectric
	This subclass is indented under subclass 52.  Subject matter which includes a photosensitive detector to receive the light transmitted through the egg, and which may include an optical filter in the visual range to restrict the characteristic of the light transmitted through the egg. SEE OR SEARCH THIS CLASS, SUBCLASS: 36, for sample preparation of the tested egg in addition to the candling step. 51, for infrared, ultraviolet and visible light transmission through the egg. 407, for color tests responsive to plural colors simultaneously. 418, for color tests including rotating filters. 419, for color tests including multicolored filters. SEE OR SEARCH CLASS: 209,  Classifying, Separating, and Assorting Solids,   subclasses 510+ for automatic egg candlers and sorters. 250,  Radiant Energy,   subclasses 336.1+ for egg candlers utilizing an infrared or ultraviolet responsive electric signalling device. 359,  Optical: Systems and Elements,   subclasses 350+ for optical elements used in the infrared or ultraviolet portion of the electromagnetic spectrum, and subclasses 885+ for optical filters.

54	With counting, marking, or weighing
	This subclass is indented under subclass 52.  Subject matter wherein a visual candling apparatus is combined with counting, marking or weighing apparatus which is used in conjunction with the candling operation, when not provided for in any other class. SEE OR SEARCH THIS CLASS, SUBCLASS: 72, for the general combination of a visual optical test and a diverse art device. SEE OR SEARCH CLASS: 101,  Printing,   subclass 2 for the combination of printing and sorting, subclasses 212+ for rolling contact printing machines and subclass 327 for printing members and inkers. 177,  Weighing Scales,   subclasses 50+ for the combination of scale with a testing device other than a candling operation and subclass 245 for weighing devices combined with a diverse art device. 209,  Classifying, Separating, and Assorting Solids,   subclasses 510+ for the combination of visual candling means with an automatic egg weighing and sorting device; and subclass 939 for illuminating means facilitating visual inspection. 235,  Registers,   subclass 91 for counting of articles mechanically. 377,  Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits, and Systems Using Pulse Counters, Pulse Divider Systems,   subclass 6 for counting articles electrically.

55	With egg transfer
	This subclass is indented under subclass 52.  Subject matter wherein transporting or conveying means is combined with a visual candling device to move eggs in a predetermined or random manner from one location into, through, or over the visual candling device and beyond the candling device to a second location by the same or a second transfer means. (1) Note. The first location may include dispensing means and the second location may include an egg holding container such as a portable receptacle where no provision is made for this combination in another class. (2) Note. Egg supply and/or conveying structure may be included to bring eggs to the candling apparatus and receiving apparatus; and additional conveying structure may also be claimed with the candling apparatus where there is no provision for the combination in another class. (3) Note. The transfer means may be gravity and motorized conveyors including those of the endless belt and disc type. (4) Note. Subcombinations of a photoelectric candling apparatus will be found here when there is no photoelectric circuitry claimed. (5) Note. Inverting structure which merely inverts an egg or a group of eggs is not considered to be a transfer apparatus for this group of subclasses unless there is additionally movement of the egg from one location to another. See subclasses 56 and 65 for egg turning or jarring structure.

56	With egg turning or jarring
	This subclass is indented under subclass 55.  Subject matter wherein structure, which may be hand, motor, or gravity actuated, is included with the egg transfer and candling apparatus to turn or jar the eggs during the candling operation. SEE OR SEARCH THIS CLASS, SUBCLASS: 62, for egg turning and jarring means combined with a light shading candling chamber. 65, for egg turning and jarring means combined with a light candling box. Also see (5) Note of subclass 55. SEE OR SEARCH CLASS: 414,  Material or Article Handling,   subclass 433 for article rotators of the roller type, and subclass 431 for the rotation and a simultaneous advancement of articles which are concurrently engaged at the ends of the articles.

57	Endless conveyor
	This subclass is indented under subclass 56.  Subject matter wherein there are manually or motor driven endless conveyors which include structure which causes eggs placed sequentially on the conveyor to turn or somehow move while passing through, over, or on the visual candling apparatus. (1) Note. Automatic structure to place the eggs on the conveyor from a supply structure and structure to remove the eggs from the conveyor may be included in the claimed combination. See also the Search Notes under subclass 58. SEE OR SEARCH CLASS: 53,  Package Making,   subclass 167 for the combination of candling, conveying, and the filling of portable receptacles. 198,  Conveyors: Power-Driven,   subclasses 343.1+ and 373+ for an endless conveyor having means for turning or orienting the conveyed load as the conveyor advances, and subclass 631 for an endless conveyor having means to jar the load as the conveyor advances.

58	Endless conveyor
	This subclass is indented under subclass 55.  Subject matter wherein the transfer means is an endless conveyor of the manually or motor driven type and which includes endless belt and disc type to sequentially bring eggs singularly or in groups, up to, over, or through the candling device; and usually to convey the eggs beyond the candling structure to broad receiving means. (1) Note. Inverting structure may be included in the conveying structure. SEE OR SEARCH CLASS: 198,  Conveyors: Power-Driven,   subclasses 373+ , 418+, and 434+ for arranging articles on conveyors including the orienting of articles on or between conveyors; subclasses 606+ for endless conveyors successively conveying a load; subclass 779 for traveling roll type conveyors; and subclasses 688+ and 804+ for endless belt conveyors. 209,  Classifying, Separating, and Assorting Solids,   subclasses 510+ for egg sorting apparatus; subclasses 702+ for manual sorting apparatus; and subclass 912 for endless feed conveyors having means for holding items separately.

59	Manual transfer
	This subclass is indented under subclass 55.  Subject matter wherein the transfer means is a hand manipulative support which may contain the eggs in a random or predetermined manner, and which may function separately as a hand held conveyor to move the supported eggs from one location to another and as a complete candling unit with the light source. (1) Note. Included herein with the manual transfer supports are the light box candling devices. (2) Note. Pivoted egg support trays attached to the candling box for the purpose of inverting the eggs are not considered conveyors and are placed in subclass 64. SEE OR SEARCH THIS CLASS, SUBCLASS: 64, for light candling boxes. See also (2) Note above.

60	With light shading chamber
	This subclass is indented under subclass 59.  Subject matter wherein the candling device is a light shading chamber, and the hand manipulated transfer device is inserted within the light shading chamber for the candling operation. (1) Note. The transfer device may be stationary or manually movable during the candling operation. SEE OR SEARCH THIS CLASS, SUBCLASS: 62, for light shading chambers generally in candling apparatus.

61	Portable receptacles
	This subclass is indented under subclass 59.  Subject matter including portable receptacles or hand carried trays, per se, which are adapted as by an opening or transparency to pass light to or from the egg and which when used with light box and light shading chamber structure form visual candling devices. SEE OR SEARCH THIS CLASS, SUBCLASS: 244+, for sample, specimen, or standard holders or supports generally. SEE OR SEARCH CLASS: 229,  Envelopes, Wrappers, and Paperboard Boxes,   subclass 29 for folded blank boxes of the compartment type with a wrapper to completely cover the cells designed to candle or inspect eggs held therein. 294,  Handling: Hand and Hoist-Line Implements,   subclass 87.12 for multiple egg hand transfer devices with lifters or grapples, and subclass 137 for hand-held article carriers.

62	With light shading chamber
	This subclass is indented under subclass 52.  Subject matter including an enclosure, adapted to be joined to a light box by an aperture which passes the candling illumination from the box, to darken the viewing field adjacent the eggs. SEE OR SEARCH CLASS: 312,  Supports: Cabinet Structure,   subclass 223.5 for enclosures having illuminating means.

63	Hood type
	This subclass is indented under subclass 62.  Subject matter wherein the enclosure is a hood which is attached externally to the enclosure to aid in the observation of the candling light. SEE OR SEARCH CLASS: 362,  Illumination,   subclasses 351+ for shades and their supports for preventing the further distribution of light.

64	With light box
	This subclass is indented under subclass 52.  Subject matter wherein there are enclosures of candling illumination (including natural light directors) which have an aperture or apertures to support or locate exteriorly on the surface of the enclosures an egg or eggs to be candled. (1) Note. This subclass includes those enclosures which utilize sunlight as the source of candling illumination and which require an additional aperture or apertures on the periphery of the enclosure to allow the illumination transmitted through the egg or eggs to be visually observed exteriorly of the enclosure. (2) Note. These enclosures include optical elements such as mirrors to direct the illumination radiated through the egg or eggs to the outside of the enclosure through the additional aperture or apertures so that a visual observation can be made. SEE OR SEARCH CLASS: 40,  Card, Picture, or Sign Exhibiting,   subclasses 564+ for lamp boxes, and subclasses 361+ for transparency viewers. 211,  Supports: Racks,   subclasses 14+ for plural egg supports generally. 248,  Supports,   subclasses 176+ for article stand type supports where only a singular article is supported and subclass 346 for supporting bases.

65	With egg turning or jarring
	This subclass is indented under subclass 64.  Subject matter wherein structure is included to move or jar the eggs during the candling operation. SEE OR SEARCH THIS CLASS, SUBCLASS: 56, for egg candling with egg transfer including turning or jarring. SEE OR SEARCH CLASS: 414,  Material or Article Handling,   subclass 431 for the rotation and simultaneous advancement of articles which are concurrently engaged at the ends of the articles and subclass 433 for article rotators, roller type.

66	With particular illumination means
	This subclass is indented under subclass 64.  Subject matter wherein the enclosure internally contains significant illumination means or where the illuminating means is significantly related to the remaining candling structure. (1) Note. The illumination means may be of the electrical or combustible type which may or may not be of the self contained power type. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclasses 453.11+ for an irradiated object and subclasses 458.1+ for methods and apparatus for irradiating luminescent material generally.

67	With particular electrical switching
	This subclass is indented under subclass 66.  Subject matter including electrical illumination controlled by a significant electrical switch or switch operating structure to connect the illumination means to a power source, or where the switch and the switch operator are significantly related to the remaining candling structure. SEE OR SEARCH CLASS: 200,  Electricity: Circuit Makers and Breakers,   subclasses 52+ for switches of special application, particularly subclasses 61.41 and 61.42 where the motion or presence of an article actuates a mechanical feeler to close an electrical switch and subclass 61.58 for switches actuated concurrently with the operation or use of an art device.

68	Lamp attachments
	This subclass is indented under subclass 52.  Subject matter including structures attachable to illuminating lamps to convert the illuminating lamps into candling boxes or light shading chambers of the visual type. (1) Note. Included are devices to convert portable and other type light sources into egg candling structure. SEE OR SEARCH THIS CLASS, SUBCLASS: 72, for convertible subject matter not classified elsewhere. SEE OR SEARCH CLASS: 313,  Electric Lamp and Discharge Devices,   subclass 315 for incandescent lamps. 315,  Electric Lamp and Discharge Devices: Systems,   particularly subclasses 32+ for incandescent lamps which are structurally combined with a circuit element, and for systems for supplying electrical energy to lamps. 362,  Illumination,   subclasses 138+ for inspection lamps, subclasses 157+ for portable electric lamps, and subclasses 257+ for lanterns including light projectors not specifically designed for testing purposes.

69	CUTTING BLADE SHARPNESS
	This subclass is indented under the class definition.  Subject matter including a light source for shining light on a blade edge together with optical or photoelectric means for determining the reflectivity and thus the sharpness of the blade. SEE OR SEARCH THIS CLASS, SUBCLASS: 445+, for reflection testing generally. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclasses 104+ for testing surfaces and cutting edges where not elsewhere classified. 209,  Classifying, Separating, and Assorting Solids,   subclasses 511 , 524+, 536, and 576+ for testing articles with radiant energy including means to sort the articles.

70	OIL TESTING (E.G., CONTAMINATION)
	This subclass is indented under the class definition.  Subject matter including structure for determining the physical properties of liquid oil by the optical response, such as produced by visible light transmitted through or reflected from the oil. (1) Note. The optical response may involve the examination of the oil for color, polarization effects, or for foreign content such as sediment in the oil. Both visual and photoelectric devices are here, and the test may be of oil samples or of oil moving in a closed system. SEE OR SEARCH THIS CLASS, SUBCLASS: 51, for tests of oil which may involve infrared radiation. 128+, for refraction test devices which may be applicable for testing of oil. 364+, for polarization test devices which may be applicable for the testing of oil. 402+, for color test devices which may be applicable for the testing of oil. 432+, for transmission test devices particularly for comparison tests, and 441+, for liquid particle suspension tests. 445+, for reflection test devices which may be applicable to the testing of oil. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 28 for testing for solid matter entrained in a gas, subclasses 61.41+ for the testing of a liquid for sediment or foreign content where more than a visual or photoelectric test of the color or the amount of visible radiation transmitted through or scattered from the liquid is involved, and subclasses 53.05+ for lubricant testing, subclasses 152.18+ for a fluid analysis in testing a borehole, a casing, or a drill rigging wherein the test is not purely electrical or purely magnetic, in particular subclass 152.42 for determining the relative proportion of fluid constituents by a test which is not purely electrical or purely magnetic. 116,  Signals and Indicators,   subclasses 200+ for visual indicators, per se, where no color or other optical comparison test is involved and for level indicators of the mechanical type.

71	DOCUMENT PATTERN ANALYSIS OR VERIFICATION
	This subclass is indented under the class definition.  Subject matter for the analysis of intrinsic properties of documents which includes a support for the document to be tested and means to examine and compare visually or to examine photoelectrically the properties of the document by means of visible light for the conformance of any given property with a standard or for the conformance of the pattern or writing generally with a standard pattern or writing as to form or configuration. (1) Note. A document for this subclass is a sheetlike article and may be an information document having writing or printing or containing a pattern. A document is, however, excluded from this subclass when any writing, printing, or pattern contained on the document is examined for the information it conveys. (2) Note. The analysis of the intrinsic properties of a document by means of radiant energy (nonvisible light), is classified in Class 250, Radiant Energy. (3) Note. The analyzing of coded cards, having perforations, magnetic markings and visible markings, one at a time in business machines as well as the cards, per se, are in Class 235, Registers. (4) Note. Termatrix Systems (peekaboos) are found in Class 235, Registers, subclass 1; Class 250, Radiant Energy, subclasses 211 and 219. Also see Class 355, Photocopying, for projectors involving peekaboo systems. SEE OR SEARCH THIS CLASS, SUBCLASS: 2, for contour plotting apparatus involving stereoscopic images of topographical maps. 389, for mensuration or configuration comparison generally where a photograph is taken of the standard or object to be compared. 391, for configuration comparison generally of an article with a standard where light projection is involved. 394, for configuration comparison generally of an article with a desired shape. SEE OR SEARCH CLASS: 73,  Measuring and Testing,   subclass 156 for statistical record verifying of punched or marked cards. 194,  Check-Actuated Control Mechanisms,   subclass 207 for the testing of currency for genuineness combined with a check controlled machine. 209,  Classifying, Separating, and Assorting Solids,   subclasses 576+ , 603, and 659+ for one or more tests involving documents for length, width, thickness, color, light transmission tests and pattern analysis where a physical separation of a document from other documents is based upon one or more of these tests. 235,  Registers,   subclasses 375+ for systems controlled by a record, subclasses 435+ for the analysis or recognition of a coded document which does not include reading or sensing of alphanumeric characters or pattern recognition. 250,  Radiant Energy,   subclasses 556 and 233 for the light detection of patterns on documents and the light detection units, per se, which involve rotating masks and shutters and subclass 271 for coded record recorders responsive to invisible radiation or invisible radiation modified by the code. See also (4) Note above. 340,  Communications: Electrical,   subclass 146.2 for the comparison electrically of information where not elsewhere classified. 382,  Image Analysis,   subclasses 119+ and 124+ for signature and fingerprint analysis which include information contents.

72	WITH PLURAL DIVERSE TEST OR ART
	This subclass is indented under the class definition.  Subject matter wherein the subject matter of this class is combined with the subject matter of another class where not elsewhere provided. (1) Note. Included is convertible subject matter involving subject matter of another class not provided for elsewhere which converts an optical test apparatus to a test apparatus of another test class or to another art device. (2) Note. Where the subject matter of another class prepares the substance tested for an optical test of this class, see subclass 36. SEE OR SEARCH THIS CLASS, SUBCLASS: 68, for structures to convert regular lamps to egg candlers.

73	PLURAL TEST
	This subclass is indented under the class definition.  Subject matter which includes optical test apparatus to perform simultaneously or sequentially at least two different optical tests which are both a part of the basic subject matter of this class. (1) Note. Two identical optical tests which are part of the subject matter of this class, performed simultaneously or sequentially will be classified here providing each test has its own indicator or manner of determining its test individually rather than both tests collectively operating a single indicator. (2) Note. Included here is convertible subject matter which would permit an optical test device which is part of the basic subject matter to be changed into a optical test device which is also the basic subject matter of this class. (3) Note. Light meters which by a change in the galvanometer scale or by addition of a color filter to become a pyrometer or a colored light meter are not considered to be convertible for this subclass. See the section on pyrometers, spectroscopy, or shade or color for proper classification of this subject matter. (4) Note. Visual inspection simultaneously or sequentially with a optical test of the class will be classified here.

73.1	FOR OPTICAL FIBER OR WAVEGUIDE INSPECTION:
	This subclass is indented under the class definition.  Subject matter wherein there is means to examine one or more transparent elongated structures (e.g., rods, fibers, or pipes) which are used to transmit light rays from one point to another within the confines of their outer surface, and involving internal reflections or modal transmission. SEE OR SEARCH THIS CLASS, SUBCLASS: 384+, for measurement or tests of nonoptical fibers, width or diameter. 429+, for optical inspection of nonoptical fibers, per se. SEE OR SEARCH CLASS: 250,  Radiant Energy,   subclasses 559.01+ for circuits for evaluating a web, strand, or strip; and for detection of defects or flaws in a web, strand, or strip. 385,  Optical Waveguides,   appropriate subclasses for optical fibers, per se.

121	LAMP BEAM DIRECTION OR PATTERN
	This subclass is indented under the class definition.  Subject matter including structure to indicate or otherwise determine the direction the axis of a light beam from a headlight or other light projector; or including structure to determine at selected and fixed points the intensity of a light beam projected from a headlight or other light projector throughout the space where the light is projected, i.e., the contour pattern of the light beam. (1) Note. This class provides for the direct analysis of the beam which is emitted from the light producer, as by determining the direction pattern, or focusing of the beam. Class 33 provides for the mechanical sensing of the direction of a headlight without involving the light beam. However, where the mechanical sensing device involves some optical measuring, classification is in this Class 356. Class 362 provides for lamps where significant lamp structure is claimed in combination with a built-in optical structure. Class 324 provides for testing the electrical operating characteristics of electric lamps alone or in combination with light intensity, direction, pattern, or focusing tests of this Class 356. SEE OR SEARCH THIS CLASS, SUBCLASS: 3+, for optical range finders in combination with light beam alignment or focusing apparatus. 124+, for the testing of a lens or reflective image former where apparatus similar to that used in these subclasses is utilized to determine the quality of the lens or the reflective image former. 138+, for determining generally the two dimensional alignment of an axis or line with respect to a plane, and particularly subclasses 141.1+ and 152.1+ for the photoelectric apparatus and subclass 154 for the viewing screen type of apparatus. 213+, for photometers generally and particularly subclasses 218 for the photoelectric type, and 229 for the visual comparison type. SEE OR SEARCH CLASS: 33,  Geometrical Instruments,   appropriate subclasses, particularly subclass 264 , for lamp alignment device of the light ray type and subclass 335, for means used in aligning an automobile headlight by establishing its relationship to the horizontal or the vertical. 324,  Electricity: Measuring and Testing,   subclasses 20+ for the combination of optical alignment or focusing test of a lamp with an electrical operating characteristic test of the lamp. See (1) Note above. 359,  Optical: Systems and Elements,   subclasses 443+ for projection screens generally. 362,  Illumination,   subclasses 459+ , for significant illumination apparatus for vehicle lighting purposes. Also see (1) Note above. 445,  Electric Lamp or Space Discharge Component or Device Manufacturing,   subclasses 4 and 64, for methods and apparatus for the positioning of filaments by optical projection means during the manufacture of lamps and electronic tubes.

122	With lamp focusing
	This subclass is indented under subclass 121.  Subject matter including structure to indicate the proper focus of a light source, or the deviation or extent of deviation from proper focus of the light source. (1) Note. The proper focus usually exists when the light source is located at the focus of a parabolic reflector or lens. For classification here there must be a distinct disclosure of focusing structure in the specification or claims as opposed to a mere inherent focusing function which is classified in the generic subclass. SEE OR SEARCH THIS CLASS, SUBCLASS: 123, for the focusing of a filament with respect to some optical element wherein no light pattern is involved. SEE OR SEARCH CLASS: 362,  Illumination,   subclasses 285+ for lamps with a built-in sighting device for focusing the filament of the lamp with respect to the optical projection elements of the lamp.

123	FOCAL POSITION OF LIGHT SOURCE
	This subclass is indented under the class definition.  Subject matter including structure to establish and determine the proper focal position of a concentrated light source with respect to optical elements, such as a parabolic light reflector or a lens; or to indicate the coincidence of a concentrated light source at the focal point of a lens or parabolic reflector; or the deviation from such coincidence. SEE OR SEARCH THIS CLASS, SUBCLASS: 122, for head light focusing with direction or pattern determining. SEE OR SEARCH CLASS: 362,  Illumination,   subclasses 285+ for lamps with a built-in sighting device for focusing the filament of the lamp with respect to the optical light projection elements of the lamp.

124	LENS OR REFLECTIVE IMAGE FORMER TESTING
	This subclass is indented under the class definition.  Subject matter for measuring or otherwise determining the optical properties of a lens or reflective image former. (1) Note. Measuring means for establishing lines or points on a lens blank for the purpose of grinding or cutting are not included in this subclass. However, means for determining the optical center or the cylinder axis of a finished lens would be classified here. The former subject matter is classified in Class 33, if the measurement is made mechanically; or in other subclasses of this class particularly subclasses 138+ and 372+, if significant optical features are involved. (2) Note. Subject matter for visually inspecting a lens for flaws or imperfections is excluded from this subclass. Such subject matter is classified in subclass 239. (3) Note. The subject matter of this subclass involves testing lenses or reflectors having curved surfaces. For flatness testing generally see subclass 371. (4) Note. This subclass includes ophthalmic lens testing. However, Class 351 provides for eye testing and examination. SEE OR SEARCH THIS CLASS, SUBCLASS: 359, for determining the surface configuration of a lens or reflector by means of light interference. SEE OR SEARCH CLASS: 351,  Optics: Eye Examining, Vision Testing and Correcting,   subclasses 200+ for instruments for examining eyes or testing vision.

124.5	For optical transfer function:
	This subclass is indented under subclass 124.  Subject matter including means to determine the ratio of the Fourier spectrum of the lens image to the one of the object.

125	Focal length measuring
	This subclass is indented under subclass 124.  Subject matter for measuring the focal length of a lens or reflector. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 383 and 425+ for focusing means for compound lens systems; and subclasses 676+ and 823+ for lens focusing means.

126	Deflecting or interrupting optical path
	This subclass is indented under subclass 125.  Subject matter including means for deflecting or interrupting the optical path between a target and the observer or detector.

127	Optical center, cylinder axis, or prism measuring or determining
	This subclass is indented under subclass 124.  Subject matter comprising means for determining the optical center of a lens, the prism or deviation of the optical center from the geometrical center of a lens, or the axis of the cylinder of a lens. (1) Note. See (1) Note under subclass 124 with reference to related subject matter.

128	REFRACTION TESTING (E.G., REFRACTOMETERS)
	This subclass is indented under the class definition.  Subject matter for testing the refraction of a fluid or solid wherein there is generally means to contain the fluid or support the solid statically or in motion; generally means, which may include a light source and which may be monochromatic light, to cause a diffused or a collimated beam of light to be transmitted through the fluid or solid under test or to be transmitted and reflected internally from the surface of an optically transmissive member contiguous to the fluid or solid under test; and a visual or photoelectric device to note or measure the intensity of the light transmitted through the fluid or solid or the change in angle, direction, or the displacement of the light traversing the fluid or solid as a result of the light being refracted by the fluid or solid tested. (1) Note. Comparison tests are included under this and the indented subclass. SEE OR SEARCH THIS CLASS, SUBCLASS: 124, for the testing of optical elements such as lenses and prisms, and particularly subclass 127 for prismatic and focal power tests which may include refraction testing. 450, for interference tests which may involve the refraction of light. 496, for interference tests for determining the thickness of films which may involve refraction test. SEE OR SEARCH CLASS: 359,  Optical: Systems and Elements,   subclasses 642+ for lenses, and subclasses 831+ for prisms and prism mounts.