Abstract: A disk shaped tunable optical filter is formed by a transparent substrate in a disk shape, and a filter layer formed on a top surface of the substrate, having such a filter characteristic that a transmission central wavelength varies along a circumferential direction as a monotonic function of a viewing angle. This disk shaped tunable optical filter can be advatageously utilized in realizing a wavelength discrimination apparatus, a reference wavelength light generation apparatus, an optical packet generation apparatus, and a tunable optical filter module, which are also disclosed.

Abstract: In order to improve signal modulation characteristics and detect a position at a higher precision, collimated light of wavelength .lambda. and beam radius D enters a fixed diffraction plate and a movable diffraction plate comprising a grating of pitch "p". The grating has main diffraction components of orders .+-.1. The plates are arranged in parallel with a distance "g" between them and generally perpendicular to an optical axis of the beam. The beam diffracted by the diffraction plates and in parallel to the optical axis of the beam is condensed with a condenser lens for limiting an incident pupil size to be within D-2 g.lambda./p. The amount of the light condensed by the condenser lens is detected by a photosensor. In a different example, a collimated light beam enters a first fixed plate and a rotary diffraction plate successively to transmit diffracted light of orders .+-.1. Then, the transmitting light is guided to a symmetrical point with respect to a rotation center of the rotary plate.

Abstract: A method and apparatus for an improved autofocus in an optical system is presented. The improved autofocus system uses distinct optics from those of the primary optical system. Although optically distinct, physically, the autofocus optics are mechanically linked to the optical output stage of the primary optical system. The optical separation of the autofocus optics from those of the primary optical system overcomes the trade-offs associated with trying to combine the primary optical function and focus in the same beam. In particular, the autofocus beam is not blinded by a more powerful write beam. The physical integration of the autofocusing optics with the optical output stage of the primary optical system overcomes the difficulties associated with using external distance sensors. In particular, the autofocusing system is not susceptible to steady state error because the autofocus sensor is a true null detector.

Abstract: An encoder for encoding light moving through a grating having alternating opaque and translucent or transparent divisions thereon. Inclusion of a gradient index lens reflector into the encoder eliminates the physical mask required for resolution of finely drawn opaque lines of line pairs.

Abstract: A device for simultaneously determining the direction and wavelength of an incident light beam. The device includes a transparent block and a diffraction grating for diffracting the incident light beam to produce a number of diffracted beams within the transparent block. The device further includes a detector array generating an output indicative of positions of intersection of the diffracted beams. Finally, the device includes a processor for processing the output to determine the direction and wavelength of the incident light beam.

Abstract: A holographic grating 12 is formed on one surface of a scale substrate 11 in such a manner that a light source is disposed over the other surface of the scale substrate 11. The scale substrate 11 is formed of a transparent material. A reflection film 13 is directly deposited on the grating surface. A protection substrate 15 is adhered to the reflection film 13 on the scale substrate 11 with adhesive agent 14. Thus, a reflection-type hologram scale 1 is accomplished.

Abstract: An optical position measuring instrument, by way of which, along with other position signals regarding the relative location of two objects movable relative to one another, additionally at least one reference pulse signal regarding a defined relative position of the two objects can be generated. This instrument includes a light source, and a reference pulse transmission structure disposed upstream of the light source, which structure has a first irregular distribution of regions with two different optical properties, the beam path being divergent between the light source (LQ) and the reference pulse transmission structure (S). In addition, a reference pulse scale structure is provided adjacent to the transmission structure; this scale structure has an irregular distribution of regions with two different optical properties.

Abstract: An encoder has the capability of outputting a stable displacement signal with small distortion. The encoder includes a first scale and a second scale. The first or second scale has a scale pattern in which pattern elements are arranged in such a manner that the spacings between adjacent pattern elements are not constant but vary in phase relative to the reference phase of a reference pattern element by amounts of P/(2.multidot.L), P/(2.multidot.m), P/(2.multidot.n), P/(2.multidot.o), . . . (L, m, n, o, . . . are positive integers, P is the mean pattern period) and by amounts of combinations of sums of these values.

Abstract: Very long linear large diameter rotational, and arbitrary shape conformal fiber encoders are suggested. These devices are based on detection of non-zeroth diffraction order or interference pattern of selected diffraction orders from the fiber grating. Relative and absolute position detection or movement detection can be realized. Depending on the variety of disclosed configurations of fiber encoders, fiber grating could be either a fiber Bragg grating (refractive index modulation grating), a fiber surface-relief phase grating, or fiber amplitude or amplitude phase grating. Each of these fiber gratings may have a uniform or chirped period, and the fiber grating encoders may be implemented using transmission, reflection, or Bragg angle reflection schemes. An optical fiber may be manufactured on a continuous basis by drawing it from preform. Consequently, there is really no limitation to the length of the linear fiber based encoders.

Abstract: Provided is a signal formation apparatus for use in an interference measurement which is capable of achieving a simplicity of optical adjustments and a subminiature of the apparatus, as well as a reduction of an influence by a wavelength variation of a laser light to the utmost. A coherent light emitted from a light source section 1 is supplied to a light emission portion 3 via a connection section 2. The light emission portion 3 comprises a straight type incidence waveguide 32, a dividing waveguide 33, emission waveguides 34 and 35, and a phase modulation section 36, which are provided on an optical substrate 31. The light emission portion 3 performs a phase modulation for one of luminous fluxes and emits irradiation luminous fluxes while keeping the other luminous flux as it is. In an irradiation optical portion 4, these irradiation luminous fluxes are collimating and deflected, and irradiated onto a measurement spot of a scale section 5.

Abstract: A synchronizing light beam applied to a reference grating passes through the reference grating as a pulsed synchronizing light beam, which is converged by a convex entrance surface of a light guide rod onto a rear surface thereof. The synchronizing light beam is then diffused and reflected by a diffusion surface on the rear surface, and applied to photodiodes on respective opposite ends of the light guide rod. The photodiodes converts the applied light to a synchronizing signal.

Abstract: A spatial image separator includes a separating arrangement that separates an incident image pattern into a plurality of segments. The spatial image separator additionally includes a manner of relocating and selectively recombining a set of the segments toward at least one output position. This is accomplished in a manner which preserves information content while significantly improving energy utilization.

Abstract: An improved aligner detector is provided. The improved aligner detector includes, a detector, several electrooptic modulators, and a refractor set, which includes several wedge patterns. Each of the electrooptic modulators includes a double-refraction transistor, which has a property of double refraction. By applying a special voltage on the double-refraction transistors, the double-refraction transistors can become transparent or opaque. Thereby, the electrooptic modulators can select a desired order of the diffraction light ray. The selected diffraction light ray is refracted by the refractor set to the detector for analysis.

Abstract: A scanning unit for an optical position-measuring apparatus with a flexible printed circuit that electrically couples several electronic components. Among the components is at least one optoelectronic detector element or a radiation source that is suitable for the generation of shift-dependent modulated optical scanning signals from the scanning of a scale graduation structure. The radiation-sensitive detector face or the light-emitting face of the radiation source is oriented in the direction towards the flexible printed circuit. The flexible printed circuit has at least partially transparent recesses at least in a partial area of the radiation-sensitive detector face or the light-emitting face of the radiation source, a scanning graduation or transmitting graduation is disposed that in cooperation with the scale graduation structure makes possible the generation of position-dependent modulated scanning signals.

Abstract: In a method of detecting a position of a position detection grating mark formed with a small step structure on a surface of a flat object, an illumination light beam is irradiated on the grating mark at a predetermined incident angle. The illumination light beam includes a plurality of coherent beams having n (n.gtoreq.3) different wavelengths .lambda..sub.1, .lambda..sub.2, .lambda..sub.3, . . . , .lambda..sub.n. The n wavelengths are set to approximately satisfy the following relation within a range of about .+-.10%:(1/.lambda..sub.1 -1/.lambda..sub.2)=(1/.lambda..sub.2 -1/.lambda..sub.3)= . . . =(1/.lambda..sub.n-1 -1/.lambda..sub.n)where the wavelengths have a condition .lambda..sub.1 <.lambda..sub.2 <.lambda..sub.3 . . . <.lambda..sub.n. Photoelectric detection of change in light amount of a diffracted light component generated from the grating mark in a specific direction is performed upon irradiation of the illumination light beam having the n wavelength components.

Abstract: The target of the present invention is to provide a high speed, low-cost, multi-mode three-dimensional (3D) surface profile measurement method. The proposed Rainbow Stereo 3D Camera exploits the projected color light with a spatially distributed wavelength spectrum on the surface of objects in the scene. Multiple color imaging sensors separated by a baseline distance are used to capture stereo pair images of the scene at camera's frame rate. The 3D depth values are calculated using triangulation principle by finding pixels corresponding to a common color feature in both images. Unlike conventional stereo correspondence matching algorithms, which requires the feature extraction from a group of pixels, the proposed method utilizes a projected rainbow color pattern as unique landmarks of each pixel for correspondence registration. Essentially, the colors of pixels in a pair of stereo images are used as a "token" to perform the stereo match.

Abstract: A scanning grating is provided in a photo-electric position measuring system and the scanning grating includes several grating areas. Each one of these grating areas has a transverse grating with a graduation period. The transverse gratings of the grating areas are disposed offset by TT/4 perpendicularly to the measuring direction, i.e., in the Y direction, with respect to each other. The partial light beams diffracted at the scanning grating in the +1st and -1st order lead to an intensity modulation at a defined scanning distance Z1. An amplitude grating is provided at the location of this intensity modulation, so that by means of downstream disposed photo-detectors a scanning signal is generated by the +1st diffraction order and a scanning signal, which is phase-shifted by 180.degree. with respect to the first, is generated by the -1st diffraction order.

Abstract: The optical encoder is capable of detecting phases at positions which coincide more strictly than the phase detecting positions of a conventional optical encoder, and is thereby capable of outputting less distorted displacement signals with a sufficient averaging effect and detecting the phases more accurately. An amount of a light having passed through a first grating is received directly with a light receiving section and output as an electric signal. On the basis of the fact that the electric signal is varied dependently on a relative displacement between the first grating and the light receiving section, the relative displacement is detected. The light receiving section includes a plurality of grating-like photo detecting devices which have fine widths and are arranged in a grating-like shape in a mixed manner within a minute section so as to correspond to four phases.

Abstract: The present invention provides an optical encoder capable of using the recesses and convexes of a movable plate and a fixed plate to accurately generate a Z phase signal in synchronism with an A/B phase signal. Phase type diffraction gratings on the moving and fixed plates including a plurality of tracks with different grating pitches cause parallel coherent beams to interfere with one another, and a light receiving part detects the intensity of light to obtain a plurality of synchronous signals with different periods. On the other hand, the light receiving part detects light spots formed by condensing elements on the movable plate to generates a single pulse per rotation as a reference position. One of the plurality of synchronous signals that has the shortest period is selected as an A/B phase signal that depends on the movement of the movable plate.

Abstract: A position-measuring device for the determination of the relative position of two objects movable with respect to one another includes at least two graduation carriers connected to the movable objects on each of which, formed as chirp fields, are disposed reference mark graduation structures that serve to generate a defined signal at a known absolute position. From the scanning chirp field assigned to the scanning graduation carrier, the incident beams of a light source disposed on the illumination side and separable into at least two individual beams of differing orders of diffraction that strike at spatially separated scale chirp fields.

Abstract: An image scanner of the present invention includes an angle sensor for controlling subscanning and implemented by a position sensitive light detector (PSD). The angle sensor allows a subscanning mirror to be rotated at high speed without any vibration. A slit plate for causing a restricted part of light issuing from a light emitting element to be incident to the PSD is so configured as to cover the light emitting element, thereby reducing the size of the image scanner.

Abstract: A two-dimensional array of phase values is calculated from digitized phase-shifted shadow moire fringe patterns that are indicative of the flatness of the surface of an object. The light intensity "I.sub.1 " of a pixel in a first of such shadow moire fringe patterns is approximated by I.sub.0 +Acos.o slashed., the light intensity "I.sub.2 " of the pixel in a second of such shadow moire fringe patterns is approximated by I.sub.0 +Acos[.o slashed.+(.pi./2)], the light intensity "I.sub.3 " of the pixel in a third of such shadow moire fringe patterns is approximated by I.sub.0 +Acos[.o slashed.+.pi.], and the light intensity "I.sub.4 " of the pixel in a fourth of such shadow moire fringe patterns is approximated by Acos[.o slashed.+(3.pi.)/2)]. The phase values ".o slashed." are equal to arctan((I.sub.2 -I.sub.4)/(I.sub.1 -I.sub.3), and a first two-dimensional array of phase values are calculated.

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: An optical position measuring device, in particular for a drive for precise positioning, is recited, which comprises two drive units which are movable in respect to each other, wherein one of the two drive units has a graduation as an integral component. The latter can be scanned by a scanning unit connected with the other drive unit for generating position-dependent output signals. The graduation is directly or indirectly disposed on a level surface of the drive unit, from which a distance between the two drive units is created in such a way that by the cooperation of the two drive units the generation of a defined relative movement between the two drive units is possible.

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: The invention relates to a process for detecting luminescence with a planar dielectric optical sensor platform consisting of a transparent substrate (a) to which a thin transparent waveguiding layer (b) is applied, which sensor platform is provided with a grating for the input-coupling of the excitation light and the refractive index of said substrate (a) is lower than the refractive index of the waveguiding layer (b), by bringing a liquid sample into contact with the layer (b), and measuring the luminescence produced by substances having luminescence properties in the sample, or by substances having luminescence properties immobilized on the layer (b), optoelectronically. The invention also relates to the use of the process in quantitative affinity sensing and to the use thereof for the quantitative determination of luminescent constituents in optically turbid solutions.

Abstract: A shade layer 35 made from photosensitive material is formed on a surface of a rotational slit disk 3 of an optical encoder 1, and a slit pattern 36 is formed in the shade layer 35. This shade layer 35 is covered with and protected by a protective layer 39 made from such materials as acrylic resin. Accordingly, the slit pattern 36 can be prevented from being touched and damaged by other members. Further, the slit pattern can be prevented from being deteriorated by air. In addition, by giving an appropriate optical property to the protective layer, it is possible to make the optical property of the surface of the rotational slit disk appropriate.

Abstract: An apparatus for obtaining displacement information relative to a member includes a light source for illuminating a phase type diffraction grating on the member, an amplitude grating arranged at the position where interference fringes are generated immediately after emerging of diffracted light from the phase type diffraction grating illuminated by the light source, and a light-receiving element for receiving light emerging from the amplitude grating. The light-receiving element generates a periodic signal as displacement information upon relative movement of the member.

Abstract: An optical device reads the information such as bar codes on an object. A light-emitting element emits a read-beam. A lens cover has an inclined surface that is at an angle with the read-beam and reflects the read-beam toward a bar code, the read-beam emerging as a reflected-beam after reflection from the surface of the bar code. The reflected-beam contains a component directly reflected from the bar code and a component randomly reflected by the white and black areas of the bar code. An optical system in the form of a lens is arranged between the lens cover and the light-emitting element, and converges the read-beam to the bar code. The inclined surface is also at an angle with the reflected-beam and reflects the reflected-beam toward a second optical system in the form of a lens which in turn converges the reflected-beam emerging from the inclined surface to a light-sensing element. The light-sensing element detects the reflected-beam.

Abstract: In an apparatus for detecting information on the rotation of an object using a grating interference system, the present invention provides a rotation detecting apparatus, which can be sufficiently miniaturized even when using another rotation information detecting section at the same time, and an apparatus for controlling the rotation using the same. The apparatus has a first detecting device for detecting by making the diffracted light from the diffraction grating interfere to detect rotation information of the object, a second detecting device for detecting the light from the predetermined data recording section to detect rotation information of the object, and a light beam illuminating device common to the first and second detecting means for illuminating the diffraction grating and the predetermined data recording section together.

Abstract: A non-invasive servo-write system for use in a data recording disk drive. The system measures actuator position and generates a reference clock using semiconductor lasers. Internal position references are provided by reflective diffraction gratings affixed to the actuator arm and the spindle hub. Wavefront reconstruction optics correct for aberrations in the gratings. Optical sensors detect differential changes in the diffraction patterns created by the gratings, eliminating sensitivity to frequency drift. Decode electronics convert optical sensor data into an actuator position measurement. Control electronics drive the voice coil motor within the disk drive, which positions the write transducer to record servo information provided in a servo pattern generator. Transparent windows in the head-disk-assembly cover allow the servo-writer to write drives which are completely assembled and sealed.

Abstract: A transmission type encoder is disclosed, which comprises a main scale, a light source that radiates collimated light to the main scale, and a photodiode array that also functions as an index scale. The main scale has a rectangular grating in which light transmitting portions and light non-transmitting portions are arranged at pitch P, and each width of the light transmitting portions is set to 2p/3, whereby a third harmonic distortion in an output signal can be removed.

Abstract: A readhead for an opto-electronic encoder includes a light source, an analyser grating and a detector. The light source illuminates a scale of the opto-electronic encoder such that the light passed on by the scale forms a periodic light pattern. The analyser grating interacts with the periodic light pattern to generate a resultant fringe pattern. The resultant fringe pattern is incident upon the detector which generates a plurality of phase shifted cyclically modulating signals upon relative movement of the readhead positioned in registration with the scale. Either the periodic light pattern or the resultant fringe pattern is a linear pattern while a remaining one of the periodic light pattern and the resultant fringe pattern is an angular pattern.

Abstract: This invention relates to an apparatus for detecting rotational information, and includes a disk attachable to a spindle, with relative rotational information of the disk to be detected. The apparatus also includes a a rotation detection grating on the disk, a main body unit independent from the disk, an optical detection unit fixed in the main body unit, a light source, a reference grating, and a light-receiving element fixed to the optical detection unit. The rotational information of the disk relative to the optical detection unit is detected by the light-receiving element by detecting a light beam which is emitted by the light source and goes via the rotation detection grating and the reference grating. A positioning block for positioning the spindle attachable to the disk is also included.

Abstract: This invention provides an optical sensing system for detecting displacements of a slidable frame along an elongated plate of the system and generating corresponding position or displacement signals. The optical sensing system comprises a housing, an elongated plate horizontally installed in the housing having a plurality of positioning holes and a plurality of parallel conductors installed in it, a slidable frame having a sliding hole in its middle for slidably engaging the elongated plate, an optical sensor installed in the frame and slidably wired to the parallel conductors of the elongated plate for detecting the positioning holes of the elongated plate and generating corresponding sensing signals, and a control circuit wired to the parallel conductors of the elongated plate for converting the sensing signals into corresponding position signals or displacement signals.

Abstract: A scale for opto-electrical linear or angular measuring systems. A gradation in the form of a phase grating is embodied on the scale and has alternating raised and stepped areas. A continuous compensating layer of chrome and on it a continuous highly reflective layer of titanium nitride are applied to one side of a step-like structured base body. The material and the layer thickness of the compensating layer is selected in such a way that it counteracts the mechanical stresses of the reflecting surface layer and thus, in the finished state of the scale, the deposited layers no longer exert stresses on the base body.

Abstract: An optical displacement detecting apparatus is provided for detecting information on a relative displacement with respect to an object having a diffraction grating. The apparatus includes a light-emitting element for emitting a diverging light beam, a ball lens for converting the diverging light beam from the light-emitting element into a nearly collimated beam, a grating interference optical system for using the light beam from the ball lens to finally form interference light in such a form that two diffracted light beams from the diffraction grating are coupled, and a light detecting element for detecting the interference light from the grating interference optical system, wherein the relative displacement information with respect to the object is attained from a periodic signal from the light detecting element.

Abstract: A system and method for measuring the dimensions of a small (e.g., microelectronic) structure. The present invention is an optical system and method that uses a polarized light beam, reflected off or transmitted through, a structure, to measure the structural parameters, such as the lateral dimensions, vertical dimensions, height, or the type of structural material. The system employs a light source to generate a light beam that is polarized and focused onto the structure to be measured. The structure is illuminated with TE and TM polarized light. The structure is dimensioned such that the TM and TE fields are affected differently by the diffraction off the structure. As a result, either the TE or TM field can be used as a reference to analyze the phase and amplitude changes in the other field. Differences between the diffracted TE and TM far fields allow a comparison of the relationship between the amplitude and phase of those fields to determine the structural parameters of a structure.

Abstract: A device that is suitable for filtering odd-numbered harmonic signal components out of a periodic signal which is generated from the scanning of a periodic scale graduation using the scanning plate. The scanning plate includes a periodic sequence of individual filter elements in the measuring direction for the resulting periodicity P of the filter elements, the condition P=N.cndot.d.sub.A applies, and N is an odd-numbered integer greater than 1, and d.sub.A is a period of a scanning graduation of a scanning plate without filtering action. In the filter elements, there is a symmetrical arrangement of structural elements such that inside each filter element two complementary halves of structural elements are each provided.

Abstract: A readhead (18) measures movement in the direction of arrow (20) with respect to a scale (10). The readhead (18) comprises an index grating (12), which interacts with light from the scale (10) to produce fringes in the vicinity of an analyzer grating (14). The resulting light modulations are detected by photodetectors (16). In order to reduce the sensitivity of the apparatus to changes in the ride height (h) of the readhead above the scale, at least two different optical path lengths are provided for light travelling from the scale (10) to the index grating (12), and/or from the index grating (12) to the analyzer (14). Various ways to achieve this are disclosed, e.g. a plate (22) of a refractive medium placed in one optical path, or tilting one of the gratings.

Abstract: Because of diffraction effects caused by slits or apertures in optical measurement systems, the radiation energy which is directed towards a particular region on a sample will be spread over a larger area than desirable. By employing an apodizing filter in the radiation path in such system, diffraction tails of the system will be reduced. The apodizing filter preferably has a pattern of alternating high transmittance areas and substantially opaque areas where the locally averaged transmittance function is an apodizing function. In the preferred embodiment, the locally averaged transmittance function varies smoothly and monotonically from the periphery to the center of the filter.

Abstract: An alignment system of a lithography apparatus which is capable of obtaining an alignment mark without being influenced the height of the alignment mark and the thickness of the photoresist, includes a plurality of light sources emitting a light having each different wavelength, a plurality of beam splitters which reflects some portion of light emitted from the light source and transmits other portion of light and combines the reflected light to emit, a spacial filter for transmitting a light incident through the beam splitter, a first lens for condensing the light transmitted through the spacial filter, a wafer stage on an upper surface of which the wafer having a plurality of alignment marks to diffract a beam incident from the first lens is mounted, a second lens for condensing the light diffracted from the alignment mark on the wafer, a diffraction grating for diffracting the direction of the beam condensed in the second lens, a light collecting device for collecting the light reflected in the diffraction

Abstract: A photoelectric position measuring encoder including a scale formed of an electrically non-conductive material and having a graduation, a scanner for photoelectrically scanning the graduation and displaceable relative to the scale in a measuring direction for generating a position-dependent signal, a slide or roller element for supporting the scanner on a scale surface, and an electrically conductive element with which the scanner-supporting scale surface region forms an electrical contact and which is connected to a reference potential.

Abstract: A laser beam scanning optical apparatus which has Moire fringes generating elements which is located near a position optically equivalent to a scanning surface and modulates a laser beam emitted from a laser source to generate Moire fringes. The Moire fringes generating elements comprises, for example, a first filter which has spatial grating and a second filter which has spatial grating which slants slightly with respect to the spatial grating of the first filter, the first filter and the second filter being arranged upstream and downstream respectively in an optical path. The laser beam scanning optical apparatus further has a light receiving element for receiving the Moire fringes generated by the Moire fringes generating elements. Focusing means for correcting a position of an image point of the laser beam is driven in accordance with an output of the light receiving element.

Abstract: A photoelectric path- and angle-measurement system for measuring the displacement of two objects relative to one another comprises a quantity N=n.multidot.4 of photoreceivers which are arranged in a photoreceiver matrix in such a way that the diagonals of the photoreceivers lie parallel to the diagonals of the photoreceiver matrix and the photoreceivers which detect the same phase position are electrically connected with one another, and these signals are fed to an evaluating circuit.

Abstract: An optical encoder is disclosed, that comprises a main scale 1, a light radiating means 2, and a second member 3. The main scale 1 is a first member having an optical grating 12. The light radiating means 2 radiates collimated light to the main scale 1. The second member 3 detects variations of bright images and dark images corresponding to the relative movement between the main scale 1 and the second member 3. The second member 3 comprises a glass substrate 4 and a light receiving IC chip 5. The glass substrate 4 has thin film electrodes. The light receiving IC chip 5 has a light receiving device array 51 that is in common with an index grating, is disposed on a reverse surface of the glass substrate through solder bumps 54 by face-down bonding method. A transparent resin for sealing the front surface of the light receiving IC chip is filled in a gap between the IC chip 5 and the glass substrate 4.

Abstract: A moire interferometry system and method are provided for achieving full field surface contouring with an extended depth of view of image. The moire interferometry system includes a projection system generally made up of a light source, imaging lens and a square wave grating pattern. The imaging lens is configured to filter higher order light rays passing through the square wave grating pattern so as to project a sine wave like pattern onto a desired surface. The moire interferometry system also includes a viewing system generally made up of an imaging lens, a submaster grating and a camera. The submaster grating is preferably a customized grating that may be produced by recording a grating pattern in relation to a reference surface. The camera is able to view an image anywhere within the extended depth of image and analyze the moire fringes. A determination of deviation between a test part and a reference surface provides a part inspection system.

Abstract: A system for measuring surface characteristics of an electronic interconnection component, such as a printed circuit board, by analyzing shadow moire patterns. Printed circuit boards are carried on a continuous conveyor under a grating. For each printed circuit board, a shadow moire fringe pattern is created in response to a determination that the printed circuit board is properly located under a grating and within the field of view of a camera. Fringes of the shadow moire fringe pattern are quantified over one or a multiple of analysis paths to determining if the printed circuit board is unacceptably warped, in which case a signal is generated. For each printed circuit board, multiple images can be captured and mathematically combined, by image subtraction, to produce an enhanced shadow moire fringe pattern that is analyzed for warpage.

Abstract: A detecting system for detecting a surface position of an object, includes a light source, a first grating having a light collecting function, wherein the first grating is illuminated with light from the light source, a second grating having a light collecting function, a first optical system for imaging the first grating onto the object in a direction oblique to the surface of the object, a second optical system for re-imaging the image of the first grating, on the surface of the object, onto the second grating, wherein a moire fringe is produced by the second grating and the re-imaged image of the first grating, and a photodetector for detecting a position of a converged point of convergent light as produced by the moire fringe, wherein the surface position information of the object is determined on the basis of information related to the converged point position as detected by the photodetector.

Abstract: In order to improve the accuracy of the absolute value of a wavelength of diffraction light in a diffraction grating, a gas absorption line resulting from an absorption cell 8 is used as a wavelength reference 8. When reference light is exited from a light source 7 in a wavelength reference light source 1, the reference light is transmitted to a diffraction grating 2 as transmitted light having a spectrum absorbing only light of a predetermined wavelength by the absorption cell 8 to allow it to be reciprocated in a predetermined angle range. The diffraction grating 2 produces a split light beam from the transmitted light from the absorption cell 8. The diffraction grating 2 splits the transmitted light from the absorption cell 8 to provide diffracted light and the diffracted light from the diffraction grating 2 is received by the reference light receiving unit 3.