Abstract: An absolute position detection encoder includes a coder having a track provided with first graduations of an absolute pattern and second graduations of an incremental pattern, plural sensors movable relative to the coder along the longitudinal direction of the track, and a signal processing circuit for processing detection pulse trains, obtained upon reading the first graduations by the sensors, in synchronism with the time point corresponding to approximately the mid position of the minimum reading unit of the first graduation. The encoder outputs the relative position between the coder and the sensors in the form of parallel code signals as the absolute position read out from the absolute pattern graduations on the coder.

Abstract: A photodetector module comprising an optical fiber and a photodetector which are coupled by direct optical coupling is disclosed. A photodetector chip is fixedly attached to the circular top surface, having the shape of a circle circumscribed around the photodetector chip, of a carrier having the shape of a frustum of a circular cone, or the photodetector chip is fixedly attached to the circular bottom surface, having the shape of a circle circumscribed around the photodetector chip, of a circular recess formed in the bottom of a taper recess formed in the carrier and having the shape of a frustum of a circular cone. Such a combination of the photodetector chip and the carrier enables the omission of the positional adjustments of the photodetector chip on the carrier with respect to the X-axis and the Y-axis.

Abstract: A first ohmic electrode of a light emitting diode is put into contact with an electrode plate, and a second ohmic electrode of the same is put into contact with a mesh electrode formed by a metal net. The mesh electrode is mounted on a light receiving surface of the light receiving element. When a predetermined amount of current is supplied from a power source to the mesh electrode and electrode plate, light is emitted from that portion of the light emitting diode located around the second ohmic electrode, and the light passes through the spaces of the mesh electrode, then being received by the light receiving element. The light receiving element supplies an electric signal indicative of the light to a measuring circuit, whereby the output of the light emitting diode is measured.

Abstract: An optical position determination system is described which determines the six degrees of freedom (i.e. position of orientation) of an object with respect to a two-dimensional position sensing detector. The system comprises at least three energy beams physically connected to the object and directed to corresponding points of incidence on a surface of the position sensing detector. The energy beams are selectively energized to enable the position sensing detector to provide outputs indicative of the positions of the points of incidence. A microcomputer is responsive to those outputs to calculate the position of their common point of intersection. A single position sensing detector is thereby able to provide complete, three-dimensional information on the position of the object.

Abstract: A system for establishing a base between a light projecting station and a light receiving station of a triangulating coordinate finder incorporates a target on the light transmitting station and a reflector appropriately positioned relative to a photo sensitive receiving array in the light receiving station. A beam of light is directed through a peep hole through the target onto the reflector and is reflected back onto the target. By adjusting the relative orientation of the two stations so that the light beam is reflected back from the reflecting surface in a direction substantially co-axial with the beam of light projecting through the peep hole the bases of the two stations are arranged to be substantially in the same plane and on a base line. The base length between the two stations is measured and the orientation of the projected beam and the focal axis of the receiving station are established relative to the base line to provide coordinates for the triangulating coordinate finder.

Abstract: A real-time particle sensor is provided which can monitor particles near the surface of a disk in a computer disk drive system and in the region between disks in a multiple disk stack. A laser and lens are housed in a compact cartridge which is mounted on an actuator arm of a disk. Photocells which are also mounted on the actuator arm detect light scattered by particles passing through the laser beam, and so generate an electrical signal used to count the detected particles. The sensor's small size allows a separate sensor to fit in each of the regions between adjacent disks in a stack of disks, or near the surface of a single disk.

Abstract: A row scanner (24) sequentially reads signals derived from charges on an array (10) of photosensitive elements disposed in rows and columns, and serially applied the resulting signals to a finite impulse filter (30). Within the finite impulse filter (30), the resulting signal serially read are added to provide intermediate signals corresponding to photosensitive elements equal distantly spaced from the one photosensitive element considered, and the sums of those intermediate signals are corrected by factors either measured or empirically determined for the photosensitive elements within each circle to provide a plurality of correction signals. The correction signals are accumulatively subtracted from the uncorrected resulting image signal read from the photosensitive element considered, to provide a final image signal corrected for undesired contributions due to leakage from neighboring photosensitive elements in a plurality of circles of photosensitive elements of increasing radius.

Abstract: A position signal producing apparatus, for an apparatus for project-printing a pattern on reticle onto a wafer through a project lens with ultraviolet light, for producing a position signal indicative of position of the wafer, comprises: a laser emitting two different frequency components polarized orthogonally with each other which are splitted by a polarizing beam splitter. The first and second components are reflected by first and second mirrors respectively to produce interference fringes at a given place being on an annular region within a circle defined by field angle of the project lens on the reticle through wave plates for circularly-polarizing. Another interference fringes is formed on a diffraction grating of the wafer in correspondence with the interference fringes through the project lens and a lens for achromatizing the project lens at wavelengths of the components. Another interference fringes reflected by the diffraction grating is detected by a photodetector for producing the position signal.

Abstract: An exposure apparatus includes a pulsed light source for repeatedly emitting a pulsed light; a photoelectric converting device for receiving at least a portion of the pulsed light from the pulsed light source; and a control device for controlling the emission of the pulsed light source, on the basis of a value related to a difference between a photoelectric signal produced from the photoelectric converting device at the time of emission of the pulsed light and an offset signal produced from the photoelectric converting device at the time of non-emission of the pulsed light.

Abstract: The present optical detection apparatus is adapted to measure an individual light reception value received by respective photodetectors when the light is interrupted by an object and the driving amount for light emission of the respective light emitting devices is controlled to be equal, compute and store the individual driving amount for light emission of the respective light emitting devices so that the individual light reception value may be kept constant and drive the respective light emitting devices in accordance with the individual driving amount for light emission. Accordingly, variation of the light reception value of the respective photodetectors may be eliminated thus preventing erroneous detection of an object.

Abstract: An advantageous device and method enables a photomultiplier to be gated on and off at electronic rates. A single multi-winding pulse transformer is employed to enable the triggering of the photomultiplier tube.

Abstract: An encoder for measuring movement of an optical scale by photoelectrically converting light from the optical scale obtained by applying light from a light source to the optical scale, by means of light receiving element, includes detector for detecting a variation in intensity of the light received by the light receiving element and a comparator for comparing a signal from the detector with a predetermined reference signal. Consequently, a predetermined alarm signal is generated on the basis of the result of comparison obtained from the comparator.

Abstract: The present invention provides an apparatus for detecting a light receiving position, comprising: a light receiving portion including M.times.N light receiving elements arranged along a straight line at a predetermined pitch; a plurality of M digital circuits each for outputting a detection signal when an added level of an input signal exceeds a predetermined level, the M.times.N light receiving elements being connected to the M digital circuits for N by N, respectively; a plurality of N analogue circuits each for outputting the added level of the input signal, the light receiving elements connected to the M digital circuits for N by N respectively being connected to the N analogue circuits by N, respectively; and a calculating means connected to the M digital circuits and the N analogue circuits, for calculating a light receiving position of beam light incident to the light receiving portion, on the basis of outputs from the digital circuits and the analogue circuits.

Abstract: A hybrid switch includes a snap-action switching portion having a butterfly-type mechanism and a solid-state switching portion formed within a single, compact housing. The solid-state switching portion is formed of an electro-electronic device consisting of a light-emitting diode and a phototransistor. Alternatively, the solid-state switching portion is formed of a bipolar transistor.

Abstract: A start of plot mark consists of three portions, a first, second and third portion each of equal area with the first and second portions being above a reference line and spaced from each other by the second portion which is below the reference line. The first and second portions are used to generate a reference signal for use in measuring the zero crossing of the output signal from the start of plot mark thereby to automatically compensate for uncertainties in the zero crossing such as those uncertainties produced by differences in intensities of the start of plot coloration versus the background coloration of the print medium, differences in reflectivity and illumination of the print medium, and imbalances between sensor output signals.

Abstract: The arrangement comprises a tracking sensor with a light source, an optical means and a receiver with two photosensitive detectors, as well as a measuring apparatus with a computing unit. The optical means focuses light to provide a beam which falls on a moving web of foil. The tracking sensor may, for example, be installed in a re-winding installation, and during re-winding of the web, senses by means of the beam a marking track which is embossed in the web in the longitudinal direction of the web and which is composed of two different diffraction grating tracks. Each diffraction grating track projects the light diffracted therefrom in a predetermined direction of incidence to a respective detector. The sensed signals supplied by the receiver are converted into a difference signal by the measuring apparatus, and processed to provide correction signals which are supplied to a control means of the re-winding installation in order to compensate for lateral deviation of the moving web of foil.

Abstract: A method and reflectometer used to analyze guided optical components, optical fibers or optical guide networks by time reflectometry in a time sphere. The method comprises steps of creating a light probe signal, feeding the light probe signals into the guide connected to the system, creating a pumped signal, obtaining a backscattered response signal from the system, sampling the backscattered response signal by interacting the pump signal therewith to produce a sampled signal, and receiving the sampled signal with a photodetector, which is blind to the pump signal and the backscattered response signal and will recompose the backscattered response signal from the sampled signal.

Abstract: An electro-optic power cell for transducing incoming light energy from an optical fiber into electrical energy through a photo diode. An optical fiber extends into a first housing through a wall thereof. A lens in the housing abuts and is sealed to the end of the optical fiber to expand the light beam from the fiber and direct it to a photo diode in engagement with the output end of the lens. A second housing which contains an electrical socket is fastened to the first housing. Leads from the photo diode are connected to the electrical socket so that the electrical signal from the photo diode can be connected to an external electric receptacle. The optical path is hermetically sealed to prevent entry of contaminants. Several embodiments of the photo diode are described in order to perform different functions. One embodiment uses a segmented photo diode having the segments connected in series to increase diode output voltage.

Abstract: A constant-current light sensing system employs a constant-current diode in series with the power lead to a photoconductive cell. This diode provides a substantially fixed current through the cell and enables the system to be designed such that it can make maximum use of the linear portions of the cell's output response curve, and maximum use of the range of a potentiometer's settings. The cell used in conjunction with the system is received in a housing that is easily mountable to a wall or ceiling surface by an adhesive material.

Abstract: A defect detection system and method for a pattern to be inspected wherein multiple-focus images of the pattern to be inspected are obtained and a defect on the pattern to be inspected is detected utilizing the multiple-focus images.