Abstract: A length-measuring device includes a hollow section member having a scale disposed therein. The hollow section member has a slot which extends along the scale, wherein, during position measurement, a drive dog of a scanning unit scanning the scale extends through the slot. The slot is sealed by an elastic seal extending along the hollow section member. A sleeve is attached to at least one end of the seal in a pull-off resistant manner. The sleeve has an axial abutment which is effective in a longitudinal direction of the hollow section member and with which the sleeve bears axially against the hollow section member.

Abstract: In accordance with one embodiment of the present disclosure, a difference is detected between a first image and a second image. The second image can include at least a portion of the first image reflected from a display panel and light from an object passing through the display panel.

Abstract: A video calibration device comprising an elongated image tube having a length, a first opening at one end of the image tube and a second opening at the opposite end of the image tube. The device includes an elongated sensor tube having a length, a first opening at one end of the sensor tube and a second opening at the opposite end of the sensor tube. The first opening of the sensor tube is adapted to support a video calibration sensor. A video calibration sensor is disposed in the first opening of the sensor tube. The sensor tube is sealingly secured to the image tube at an angle whereby the second opening of the sensor tube and the second opening of the image tube are substantially juxtaposed.

Abstract: A fingerprint matching apparatus includes a fingerprint distortion detection unit for detecting whether or not a correlation object intentionally distorts the finger put on the fingerprint reading face by, for example, applying excessively large force to the finger, or dragging or rolling the finger. With this configuration, it is possible to prevent a distorted fingerprint image from flowing into the fingerprint matching apparatus and therefore the probability of accurate fingerprint correlation can be increased.

Abstract: A device for determining the position of an object that is movable along at least one displacement direction, the or each displacement direction having assigned to it one length measuring device for measuring the position of the object along the respective spatial direction, includes: at least one scale extending along a displacement direction of the object to be measured as a first component of the respective length measuring device; a scanning head for scanning the scale as a second component of the respective length measuring device such that a change in the position of the scale with respect to the scanning head along the associated displacement direction of the object to be measured is measurable, one of the two components of the respective length measuring device being moved together with the object to be measured along the respective displacement direction when the latter is moved; and a device for determining the distance of the component of the respective length measuring device, which is movable tog

Abstract: A method for generating a mask for use with a light measurement system that includes a light source for projecting light onto an object, and an imaging sensor for receiving light reflected from the object. The method includes determining a profile of the object to be inspected, and generating an electronic mask based on the determined object profile. The electronic mask has an electronic opening having a profile defined to substantially match the determined object profile as viewed from one of the light source and the imaging sensor.

Abstract: A novel inspection system for inspecting an article of manufacture, such as a printed circuit board, is disclosed, where the system includes a strobed illuminator adapted to project light through a reticle so as to project a pattern of light onto an area of the printed circuit board. A board transport responsively positions the board to at least two distinct positions, where each position corresponding to a different phase of the projected light. Also included is a detector adapted to acquire at least two images of the area, each image corresponding to one of the at least two different phases. An encoder monitors the movement of the board and outputs a position output, and a processor connected to the encoder, the board transport, the illuminator and the detector controlledly energizes the illuminator to expose the area as a function of the position output, the processor co-siting the at least two images and constructing a height map image with the co-sited images.

Abstract: A method for generating a carrier frequency-modulated signal for the evaluation of n>2 photoelectric measurement signals which are generated by imaging a structured surface onto a spatial frequency filter and are phase-shifted with respect to one another is distinguished by the fact that the amplitudes of the measurement signals are serially interrogated in a predetermined interrogation cycle with a constant clock rate, and a sinusoidal signal is formed by filtering from the signal train, the carrier frequency of which signal is determined by the time for an interrogation cycle.

Abstract: A ball grid array inspection and location method and apparatus includes a raw feature finding processor which uses a feature finding algorithm to find ball features (irrespective of number) and generate a list of raw features as an X and Y location for each feature located. An angle estimation processor receives the list of raw features, a user estimated orientation angle, and ball-to-ball pitch information and determines an estimated grid angle. An on-grid check processor receives the estimated grid angle, the list of raw features and the ball-to-ball pitch information and produces a set or list of on-grid features in the form of a list X and Y translation parameters for each feature/ball found on-grid.

Abstract: The present invention provides easy-to-use, adaptable, and convenient solutions to a heretofore unmet need for instruments that can incubate and kinetically monitor assays, especially multiwell assays. In particular, the present invention finds use in monitoring assays contained within various test formats, including, but not limited to microtiter plates, miniaturized test panels (e.g., MICROCARDS™), and petri plates.

Abstract: A ball grid array inspection and location method and apparatus includes a raw feature finding processor which uses a feature finding algorithm to find ball features (irrespective of number) and generate a list of raw features as an X and Y location for each feature located. An angle estimation processor receives the list of raw features, a user estimated orientation angle, and ball-to-ball pitch information and determines an estimated grid angle. An on-grid check processor receives the estimated grid angle, the list of raw features and the ball-to-ball pitch information and produces a set or list of on-grid features in the form of a list X and Y translation parameters for each feature/ball found on-grid.

Abstract: An exposure apparatus, which has a projection optical system, a Z-stage movable in the optical axis direction of the projection optical system, an X-Y stage movable in a planar direction perpendicular to the optical axis direction, and a sensor for measuring the positional relationship between a substrate placed on the Z-stage and a predetermined position in the optical axis direction and/or any tilt of the substrate, sequentially moves and aligns the X-Y stage to change the area to be exposed on the substrate, executes a measurement using the sensor, and exposes while correcting the positional relationship between the substrate and the predetermined position in the optical axis direction and/or any tilt of the substrate in accordance with the measurement result, has a control unit for adjusting the measurement start timing of the sensor in correspondence with a change in area to be exposed on the substrate.

Abstract: A quantity of material is locally deposited on or removed from a substantially flat substrate of a circuit board. The quantity is inspected by carrying out a first measurement of a level of a surface of the material in a direction transversely of the substrate. At least two further measurements are performed of a further level of the substrate in said direction in at least two further locations where the material has not been deposited or removed. A reference level of the substrate is calculated by interpolation between the further measurements to a location of the first measurement. The quantity of material is inspected on the basis of a difference between the first measurement and the reference level.

Abstract: Displacement is measured using two overlaid parallel optic gratings as the sensing elements of a sensor head. Optic fibers are employed as the transmission media between the sensor head and a central signal processing unit. The light intensity signals of Moire fringes generated by the overlaid optic gratings are transmitted through optic fibers to the central signal processing unit. By digitally counting the number of Moire fringes, the changes in both direction and magnitude of the displacement are measured. A number of sensor heads employing the overlaid optic gratings as sensing elements are multiplexed through a common optic fiber link to comprise a multipoint sensor system. By similarly modifying the sensor head, this sensor system also measures other physical quantities such as strain, acceleration, and pressure.

Abstract: A method and device for positioning non-linear machine parts using a timing element, particularly for machine parts that are in non-linear motion. The invention has a pair of sensors spaced apart for reading bar code marks on the timing unit when the timing unit is disposed on a circular or spherically-shaped carrier surface. Where long surfaces are involved, the ends of the timing unit or clock ruler are butt-jointed together and include a gap having a width deviating from the window openings of the bar code. Thus, the second sensor, which is connected to a second comparator, contains a test circuit for the code signals that are received. When the code signals do not correspond to the width of the bar code pitch, they are passed over to a second counter, and the first counter is disconnected from the line.

Abstract: Apparatus for determining the topography of a surface of an ophthalmic object comprising a projection branch for projecting along a first optical axis a projected structured light pattern onto the surface of the ophthalmic object. The projected structured light pattern has light and dark regions that form an array comprised of horizontal features and non-horizontal edges, an algorithm in the computer establishes at least one projected virtual point for the projected structured light pattern by fitting a first function to a non-horizontal edge and fitting a second function to a horizontal feature to establish an intersection and the coordinates of the projected virtual point. An imaging branch provides a pattern image of the projected structured light pattern along a second optical axis angled with respect to the first optical axis of the projected structured light pattern.

Abstract: An optical type encoder is comprised of a gauge member and a sensor portion moved relative to each other with the movement of an object to be detected. The gauge member has a plurality of slit rows comprising a plurality of slits formed at intervals along the direction of movement of the object to be detected, and a plurality of slit intervals formed by the corresponding slits in the slit rows are made partly equal. The sensor portion has at locations corresponding to the slit rows position detecting type light receiving means for receiving light beams from light projecting means passed through the plurality of slits rows of the gauge member, and the position information of the object to be detected is detected by the utilization of signals from these light receiving means.

Abstract: A device for measuring an angle between pivotally connected, intersecting sides of a parallelogram includes a grating having a pattern of parallel, straight grating lines formed on a substrate, and a read head. The grating is mounted in a fixed position with respect to a first side of the parallelogram. The read head includes a sensor positioned for sensing displacement of the grating lines in response to an angular change between the intersecting sides of the parallelogram and generating a scale reading. The read head is mounted in a fixed position with respect to a second side of the parallelogram that is parallel to the first side. In one embodiment, the grating includes a single pattern of grating lines and is used to measure an angular change relative to a reference angle. In a second embodiment, the grating includes first and second grating patterns and is used to measure an absolute value of the angle between the intersecting sides of the parallelogram.

Abstract: According to a first aspect of the invention, an optical position sensor employs a position encoder having collimators and reflectors with mutually aligned optical axes mounted in a support. A slotted code plate moves between the collimators and reflectors in a plane non-perpendicular to their optic axes. This encoder converts position to optical signals reliably, regardless of mechanical shock or vibration. According to a second aspect of the invention, an optical position sensing system employs wavelength-division multiplexing to distribute light pulses to different position encoders and time-division multiplexing to further distribute pluses to the collimators in each encoder. This permits multiple position encoders to be served by a single light source and optical fiber.

Abstract: The three-dimensional shape of the surface of a board (12) is measured, and the parallel degree between the board (12) and a semiconductor chip (10) is adjusted on the basis of the measurement result. A board mounting means (13) and a semiconductor chip holding means (11) are moved close to each other, and the semiconductor chip (10) is mounted on the board (12).

Abstract: The three-dimensional shape of the surface of a board (12) is measured, and the parallel degree between the board (12) and a semiconductor chip (10) is adjusted on the basis of the measurement result. A board mounting means (13) and a semiconductor chip holding means (11) are moved close to each other, and the semiconductor chip (10) is mounted on the board (12).

Abstract: The incremental system for measuring lengths comprises a scale member that is provided with a measuring scale and is accommodated in a tubular projective housing, on which the scale member is held at one side edge of the scale member. A scanning unit is guided on the scale member to be movable parallel to the longitudinal direction of the scale member and comprises a light source for illuminating photoelectric receivers with light which is transmitted by a condenser, scanning gratings, the measuring scale and the scale member. A compact structure is obtained in that the scale member extends with an inclination of 45.degree. in the cavity of the carrying housing. The photoelectric receivers are provided on that side of the scale member which is opposite to a slot formed in the housing. The cone of light emitted by the light source is deflected by a reflector disposed between the light source and the condenser.

Abstract: An incremental position encoder makes use of a first and second track of non-identical non-complementary aperiodic patterns to generate a zero mark. A mask with the identical pattern to the first track and a mask with the complementary pattern to the second track correlate with the patterns on the first and second track when the encoder is in zero position. Light transmitted by the masks produce electrical signals that are compared to create the zero mark. An iterative approach improves the discrimination of an initially selected track pattern for its particular application based on developed criteria for good noise immunity and resoltuion. The size of the reference track with respect to the increment track and the placement of each mask on the stator and rotor are optimized. A system for improving noise immunity by biasing the signal from each photodetector is also shown.

Abstract: A mensuration apparatus for converting film images and paper drawings into digital photogrammatic arrays to be computer processed, displayed, mensurated and analyzed. This mensuration apparatus includes a table on whcih a translatable camera and a reseau assembly are mounted. The reseau assembly includes an object mounting plate for mounting an object such as a photograph, map, or the like, and a grid mark system for superimposing grid marks on the object. The translatable camera includes a solid state camera having a two-dimensional array of light sensor elements mounted over the reseau assembly in a translatable mounting apparatus. The translation camera can be moved to any desired position over the reseau assembly, as well as toward and away from the reseau assembly, forming three coordinate systems, which are correlated together for precise mensuration of an object image digitized by the solid state camera.

Abstract: A mensuration apparatus for converting film images and paper drawings into digital photogrammetric arrays to be computer processed, displayed, mensurated and analyzed. This mensuration apparatus includes a table on which a translatable camera and a reseau assembly are mounted. The reseau assembly includes an object mounting plate for mounting an object such as a photograph, map, or the like, and a grid mark system for superimposing grid marks on the object. The translatable camera includes a solid state camera having a two-dimensional array of light sensor elements mounted over the reseau assembly in a translatable mounting apparatus. Said translation camera can be moved to any desired position over the reseau assembly, as well as toward and away from the reseau assembly, forming three coordinate systems, which are correlated together for precise mensuration of an object image digitized by the solid state camera.

Abstract: The photogrammetrical pick up of an object with the aid of an opto-electronic solid-state surface sensor can be carried out in partial-images over a large image format if the position of the sensor in the image plane is determined by means of a reseau. This can be done by imaging at least one reseau mesh in the sensor image. After measuring the reseau points in the coordinate system of the partial-image and transforming to the nominal values in the system of the reseau, the position of the surface sensor and transformation parameters for all image points within the reseau mesh are obtained. For this purpose, the approximation position of the sensor must be known with sufficient accuracy to be able to determined the number of the reseau mesh as an unambiguous identification of the reseau points.

Abstract: An optical focus sensing system is disclosed. The system provides a focus shift measurement capability utilizing the relative motion between two gratings to produce different diffraction orders which are separately detected by a pair of detectors to form signals having a phase difference proportional to the focus error corresponding to the planes occupied by the two gratings. A control circuit is responsive to the phase difference between the signals from the two detectors to provide a controllable focusing capability.

Abstract: An optical path sensor including a filter through which passes a radiation beam comprising light of at least two wavelengths and which filter, as it is moved perpendicularly to the direction of the optical radiation beam, causes the attenuations for the beam components of different wavelengths to change in a different ratio. In a filter constructed in a simple manner with low-cost elements two phase gratings are arranged one after the other in the beam direction, only one of the gratings being movable perpendicularly to the beam direction and in that the zero-order diffraction beams are directed towards a detector.

Abstract: A position measuring instrument, comprising a scanning grid, a scale grid and an illumination unit, is used to produce two sets of diffracted partial light rays. The scanning grid defines a grid constant and is formed by two scanning fields, constructed as phase grids, offset to one another in the measuring direction by 1/4 of the grid constant. The phase grids have a slat-to-furrow width ratio that deviates from a 1:1 ratio. The scale grid has the same grid constant as the scanning grid but has a slat-to-furrow ratio of 1:1. The grids cooperate with the illumination unit to produce diffracted partial light rays of several orders. An oppositely deflecting prism is allocated to each scanning field. A first and second set of diffracted partial light rays are generated, wherein the second set is opposite in phase to the first set. A photodetector is allocated to each respective selected order of the two sets of light rays to produce corresponding electrical signals.

Abstract: A photoelectric displacement detecting apparatus for measuring a length from a repeated number of bright and dark portions of light formed by the repetitions of overlappings of slits in respective slit rows during a relative movement between a main scale and an index scale, the apparatus comprising reference marks provided on the main scale at suitable intervals, a mark detecting device provided on the index scale, identification marks provided in spaces between the reference marks for identifying these spaces, and an identification mark reading device actuated by the mark detecting device. An identification mark ascertaining device is provided for comparing the identification mark read by the identification mark reading device with the identification mark preset by a mark selecting-setting device and ascertaining whether both identification marks coincide with each other or not.

Abstract: An encoder having improved output abnormality detection. First and second input signals differing in phase from one another are compared by respective first and second comparators with a first reference level at an amplitude center of each of the first and second signals, and the outputs of the first and second comparators are applied to respective inputs of an EXCLUSIVE-OR gate. Third and fourth comparators compare a composite signal of the first and second signals with respective third and fourth reference levels located on opposite sides of the first reference level, and the output of the third and fourth comparators are applied to respective inputs of a first AND gate. A second AND gate, at the output of which the circuit output is provided, receives as inputs the output of the first AND gate and the output of the EXCLUSIVE-OR gate.

Abstract: A position measuring system for measuring the relative position of two objects movable with respect to one another includes a housing which rotatably supports a shaft connected with the first object. A first graduation disk with a first incremental graduation and at least one absolutely positioned first reference mark is mounted to rotate with the shaft. A first scanning unit for the scanning of the first incremental graduation and the first reference mark is rotatably mounted on the shaft to rotate relative to the first graduation disk and the housing. A second graduation disk is firmly connected to the first scanning unit. The second graduation disk defines a second incremental graduation and at least one absolutely positioned second reference mark. A second scanning unit is fixedly mounted to the housing which is connected to the second object.

Abstract: A synchronizing device for an electrically actuated coupling automatically coupling structural units of processing machine, includes a driving shaft and a driven shaft and two synchronizing members each connected to the assigned shaft for joint rotation therewith. A light emitter is positioned at the first synchronizing member while a light-conducting cable, receiving light from the light emitter, conducts it to a photoelectric detector connected in an electric circuit which actuates the coupling. The angular position of the first synchronizing member relative to the second synchronizing member is adjusted by clamping elements connecting the first synchronizing member to a driving gear of the driving shaft.

Abstract: A measuring scale casing or housing and spar therefor. The spar comprises integral top and back walls. The back wall is provided proximate its lower end, with a lip extending in the same direction as the top wall. The internal surface of the lip has a groove.The casing is provided with top, back and front walls and is provided with a downward protrusion proximate the bottom of the back wall. The protrusion is sized to fit within the groove of the lip of the spar in dovetail fashion when the exterior surface of the top wall of the casing is proximate the internal surface of the top wall of the spar and when the exterior surface of the back wall of the casing is flush against the internal surface of the back wall of the spar.The top wall of the casing is provided with a V-shaped groove and the spar is provided with set screws in the top wall.

Abstract: In a device for determining the angle of rotation of a rotating member by use of a perforated disk which corotates with the rotating member and intermittently interrupts a continuous beam of light directed at the perforations of the disk, an improvement comprises providing perforations of the disk which define light permeable and light impermeable areas such that a width of the light permeable areas is less than a width of the light impermeable areas, and a width of the light permeable areas is approximately the same as a width of an aperture at a light receiving station. A symmetrical output signal is obtainable so as to increase a resolution of the angle of rotation measurement.

Abstract: A photoelectrical encoder wherein a physical quantity is detected from brightness obtained by moving a first and a second scales each provided thereon with an optical grating relative to each other, characterized in that the grating in one of the scales is constructed such that a first signal lead-out material layer made of a light shielding conductive material, a PN semiconductor layer for converting light into electricity and a second signal lead-out material layer made of a light transmitting conductive material are laminated on a light transmitting base member in the described order to form a narrow belt-shaped light receiving portion and a plurality of narrow belt-shaped light receiving portions thus formed are arranged at regular pitches, as against the light from the light transmitting base member, the light receiving portions function as light shielding slits and intervals between the light receiving portions are formed into light transmitting slits.

Abstract: Apparatus for detecting the position of a movable member such as the control lever (42) of an audio fader (FIG. 2). A series of light emitting and detecting elements (Q1-Q5) define a plurality of light paths arranged over a distance of D units, and provide a first output indicating which of the light paths are blocked. A shutter (24) includes light-obscuring regions (53, 54, 56) alternating with nonlight-obscuring regions where both the light-obscuring and nonlight-obscuring regions are D units in length. The shutter travels through the light paths so as to affect the output of the light detecting elements. The shutter is coupled to the control lever so that the position of the shutter is dependent upon, and therefore indicates, the position of the movable member.

Abstract: The present invention relates to coilable extensible rules or the like. More specifically, the present invention is concerned with a new and improved optical sensing system for extensible tape rules of the type that provide a visual display of the measurment readings, such as the digital tape rule described in the Hildebrandt et al U.S. Pat. No. 4,161,781, the disclosure of which is incorporated herein by reference.

Abstract: A digital photoelectric angle or length measuring instrument, of the type having a scale with at least one division, a scanning unit for scanning the division to generate a scanning signal, and an evaluating unit having a trigger circuit for evaluating the scanning signal, is provided with means for generating at least one test signal and means for selectively applying the test signal either to the trigger circuit or to a light source such that the trigger threshold of the trigger circuit is temporarily varied by a selected amount, thereby providing a simple, reliable check of the trigger threshold of the trigger circuit, without requiring external equipment or disassembly of the measuring instrument.

Abstract: The pulse signal generating device for a tape recorder comprises a rotary plate attached to a rotating shaft portion of the tape recorder which rotates in connection with tape running. The rotary plate has a central axis, and rotates together with the rotating shaft portion around the central axis. The outer peripheral surface of the rotating body includes at least one first surface portion with a higher reflection factor and at least one second surface portion with a lower reflection factor. The first and second surface portions adjoin each other along the circumferential direction, and are located at different distances from the central axis. The pulse signal generating device further comprises a photo-reflector facing the outer peripheral surface of the rotary plate. The photo-reflector includes a light emitting element for emitting light toward the outer peripheral surface and a light receiving element to receive light reflected from the outer peripheral surface.

Abstract: A system and method of determining the angular displacement of one or more members is disclosed. A reference laser beam is diffracted, reflected and impacted upon a face of a display as a light pattern in which the pattern spacing is representative of a determinable angular displacement relative to a reference pattern.

Abstract: An encoder for accurately determining the position of one body relative to another consists of an optical mask carried by one body which moves through the focal point of a concave reflector carried by the other body. The reflector produces an image of the mask in the same plane of the mask and the mask and its image together produce positional information which is utilized by a photo-sensitive detector. The optical pattern of the mask is arranged such that the detector receives constant variations in the levels of illumination as the mask moves.

Abstract: The invention is for color separation orientation gauges and methods by which they are used to produce a finished print in more than one color, the colors used being the primary colors and black. In the printing trade, the primary colors are at times referred to as magenta, yellow, and cyan. The color magenta is basically red, cyan is basically blue and, of course, yellow is basically yellow.The gauges utilized are provided with a predetermined number of dots disposed at various angles depending, for example, on the color to be eventually printed, which gauges are superimposed on a half-tone mask of which there are also a predetermined number of dots which are practically invisible to the naked eye. The gauges of the two embodiments of the invention are provided with special reference line dot densities and angles and legends to provide the color stripper with easy to use compact gauges for producing multi-color prints.

Abstract: An opto-electronic transducer is provided for converting small displacements into optical intensity or phase variations which may then be converted into varying electric currents. A first optical fiber guide is disposed with its end face stationary, for example, while a second optical fiber guide is disposed so that its free end may be laterally displaced from the axis of the first guide in proportion to the parameter to be measured. The sensitivity of the transducer is enhanced through the use of large core, large numerical aperture, multimode optical fibers. The opposed faces of the cooperating fibers are equipped with or are used to illuminate regular arrays of equally spaced opaque, absorptive, or reflective grating systems providing intensity or phase modulation of the propagating light energy in proportion to wave guide deflection.

Abstract: A process and mask for use in the process making it possible optically to measure precisely and rapidly sizes in elevation. A group of fringes of regular light, in uniform translation at constant velocity, is projected on the object to be measured and the image of the projected fringes is observed. The measurement of the phase difference of the reflected or diffused light signal at two points of the masked image plane is proportional to a variation in the relative height of the two corresponding object points, thereby allowing comparison to a control piece. The process makes it possible to measure absolute or relative sizes in elevation at two critical points of pieces in a production line. It also makes it possible to determine the profile of any piece.

Abstract: A linear scale type measuring device wherein an index scale mounted on a slider is opposed to a linear scale, the displacement of a movable member is imparted to said slider through connecting means and the relative displacement between the linear scale and the index scale is read by use of a light source and a receptor element both of which are provided on the slider, characterized in that said connecting means comprises a first engageable member provided at the forward end of a cantilever spring for biasing the slider toward the linear scale and a second engageable member engaging said first engageable member, and one of said first and second engageable members is formed into a projection or a recess provided with a tapered surface and the other is formed into a hole engageable with the tapered surface of said projection or cornered portion engageable with the tapered surface of said recess, said hole or the cornered portion being made of a ring-like portion which the forward portion of said cantilever spri

Abstract: In a grating measuring system of a basic type originated by DeLang employing a concave mirror-lens main optical system introduced by Dyson, improved separation of the light fluxes of input illumination and output motion-modulated signals is achieved. The arrangement depends upon the fact that in such a system wherein the grating is imaged back on itself so that for every point in the half plane containing the grating surface at one side of the optical axis, there is a conjugate point in the half plane at the other side of the axis. Separation by reason of beam separation is attained by illuminating one half plane and deriving output signals from the other. Further separation is attained from the fact that the concave mirror lies in a so-called "complementary plane" or "Fourier plane" to the object-image plane. Each point in the complementary plane is the focus of all rays originating in the object-image plane in a particular direction.

Abstract: An optical incremental shaft encoder in accordance with this invention involves an illumination source arranged to direct light through an optical slit, with the light then falling upon a series of very closely spaced lines forming a first grating. I have discovered that close by this grating a series of image planes are formed, with each plane containing multiple images of the slit. Generally, these images are distinct for distances of only 1/10th of an inch or less with respect to the grating or mask, and for the purpose of this invention, I do not use image planes further away from the mask or grating than this distance. I have found a way to utilize this diffraction phenomenon to great advantage by providing another grating-like member, placed at a selected one of the image planes, whose line spacing is identical to the image line spacing.

Abstract: An improved scanning grating useful as an image scanner and spatial frequency filter, for a focusing detector to ascertain the focus of an optical system on deflecting the light incident from the optical system into two different directions for forming two images of the exit pupil or of parts thereof of said optical system. A slit grating is superimposed over the groove grating so that the ledges cover the peaks and the troughs thereof. It is thereby attained that the signals obtained from the peak and trough areas, which normally are more or less undefined, are exempt from evaluation. The ledges have a width ranging from 10 to 100 percent of that of the slit width.

Abstract: Apparatus for monitoring and controlling the operation of a dual platen press used in the manufacture of nuclear fuel pellets is disclosed. The apparatus includes means for indicating the displacements of both platens and imposing the displacements of the platens on orthogonal axes such that the displacements jointly control the motion of a point which traces a lissajous figure representative of the displacement and relative velocity of the press platens. A second lissajous figure representing the desired platen movements and relative velocity may be superimposed on the first lissajous figure, differences between the first and second lissajous figures indicating deviations from the desired operation of the press. Alternately, a press operator may simply use the first lissajous figure constructed from the actual platen displacements to analyze the operation of the press. The completion of preselected portions of the first lissajous figure may be detected and used to trigger subsequent press operations.