Abstract: Dynamic behavior of structures subject to vibrations is monitored with light coupled into a single multi-mode optical fiber positioned within or on the structure. Vibration caused strain or deflections in the structure are detected by interference light signal intensity variations caused by differential phase changes in the transmission modes. These intensity variations are optically detected to provide an electrical output. Actuators may be positioned at the vibration nodes of the structure and energized by signals derived from the electrical output signals to suppress the vibrations.

Abstract: A sensing system and method for detecting changes in the level of a liquid surface utilizing a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward a liquid surface at an oblique angle thereto, and thereby providing a reflected beam therefrom. A beam expander is interposed between the illumination source and the liquid source for increasing the narrow beam width of the incident beam to a beam width substantially greater than the wavelength of disturbances in the liquid surface. A converging lens is mounted transverse to and intercepts a portion of the reflected beam from the liquid surface for focusing that portion of the reflected beam to a centrum. A beam detector is positioned adjacent to the centrum for providing an indication of changes in the level of the liquid surface by detecting corresponding changes in a relative position of the centrum.

Abstract: An automatic focusing device includes an optical head which comprises a focusing lens system and an optical sensor. The focusing lens system focuses a reading laser beam or a recording laser beam on an optical disk. The optical sensor generates photoelectric signals which correspond to the sections of a beam spot formed by a laser beam reflected from the optical disk. Record signal components corresponding to a recording laser beam are removed from the photoelectric signals by switch circuits. The photoelectric signals no longer containing record signal components are supplied to envelope detectors. The envelope detectors generate envelope signals each formed of signal components which correspond to a laser beam reflected from the surface of the optical disk. According to the difference between the envelope signals the focusing lens system is driven to thereby focus a laser beam on the optical disk.

Abstract: A method of determining the precise location of an edge of a strip with individual elements of a radiation responsive sensor to an accuracy exceeding the pitch of the elements is disclosed. The strip is scanned at least in the region of the edge with the individual elements of the radiation responsive sensor. Each element generates a signal value associated therewith for each scan and the signal values for all the elements form a composite signal having discrete values representative of radiation received form the scanned region at respective locations corresponding to the individual elements of the sensor. A region of interest where said edge is likely to lie is identified and the composite signal is analysed by defining a curve which when the values are plotted against the locations on a distance scale passes through the values to represent a radiation profile of the scanned region as received by the sensor.

Abstract: A photoelectric instrument detects dissimilar variations in a viewing corridor and provides an alarm signal responsive to such changes. A lens, such as a camera lens, is mounted on a case and separate photoelectric sensors are adjustably positioned in the focal plane of the lens within the case. The photoelectric sensors are moved relative to each other to define a viewing corridor of interest. The photoelectric sensors are coupled to a differential amplification network and the inputs to the amplification network are adjusted to produce a reference signal. Deviations of the differential amplification network output from the reference signal indicate an intrusion or non-uniform alteration of the field of view, which results in an alarm signal.

Abstract: Provided is a sunlight direction sensor having a cylindrical body, a nontransparent flange having a diameter smaller than the inner diameter of the cylindrical body, a first photosensor disposed on the flange or substantially at the center of the inner bottom surface of the cylindrical body, and at least one pair of second and third photosensors which are disposed at the inner bottom surface of the cylindrical body and which are arranged symmetrically with respect to the axis of the cylindrical body, inner edges of the second and third photosensors corresponding to the inner periphery of the flange.

Abstract: A system for focusing an optical head onto a flat surface has a mechanism for moving the optical head in the direction of the optical axis of the head and a mechanism for moving an objective lens in the optical head in the direction of the optical axis of the lens. A laser beam projected from the objective lens of the optical head is reflected on the flat surface, is reflected on the beam splitter, and is introduced into a detector unit. The detector unit thus generates a focusing signal having a level responsive to the distance between the objective lens and the surface. The optical head is lowered by the mechanism for moving the optical head in accordance with the focusing signal when it passes a predetermined point, and is operated to locate the focal point of the objective lens on the surface. Thereafter, the mechanism for moving the optical head becomes inoperative, and the mechanism for moving the objective lens is operated.

Abstract: An electrical contact unit comprises a flexible semiconductor, e.g. silicon, filament carrying contacts and having a shorted pn junction. The filament is mounted in a magnetic field. When light is directed on to the junction, e.g. from an optical fiber, the induced photo current flowing around the short circuit interacts with the magnetic field so as to bend the filament so as to establish connection with one or more adjacent fixed contacts.

Abstract: An arrangement for determining the position of an index line relative to a graduation scale, particularly for use in goniometers which operate physically is constituted of a graduation track, a code track and a pulse track, a mask is associated to said tracks having a number of openings which embody a code for a respective value of an encoded graduation mark. The counted measuring values derived from the graduation marks and from the code track are fed into a storage, for example, a shift register.

Abstract: An apparatus is disclosed for effecting a focus control of an objective lens with respect to a track having a crenellated pit construction recorded on an optical disc on which a light beam emitted from a laser light source is to be focused as a light spot by an objective lens. A light beam reflected by the disc is introduced via a reflection surface which is set substantially at a critical angle with respect to an optical axis onto a photodetector having four light receiving regions divided in orthogonal directions. A first focus signal is produced by deriving a difference between photoelectrically converted output signals from the light receiving regions in response to a variation in an average amount of the light projected on the photodetector.

Abstract: A device for detecting unacceptable defects in a neck area of hollow glass articles transported by a feeding element has a light source spaced from a path of feeding of the articles and arranged to illuminate the neck area of the latter, a projecting element arranged to project an image of the neck area of each of the glass articles, an image receiving element arranged to receive the projected image of the neck area and having a plurality of electrooptical elements, wherein the projecting element includes a mirror arranged to project the image of the neck area of each of the articles along a projecting axis which is transverse to the longitudinal axis of the device, and the electrooptical elements are arranged in a circle located in a plane normal to the projecting axis.

Abstract: Device for determining the orientation of an axis, mobile about a point, of a solid in rotation about this axis, particularly a gyroscopic spinner, wherein said device comprises a portion of sphere centered on said point of said axis, of which the surface comprises at least two parts which are respectively absorbent and reflecting for a given radiation, and sensor means sensitive to the radiation reflected by the sphere, the reflecting and absorbent parts being shaped so that the sensor means deliver signals characteristic of the orientation of said axis.

Abstract: A fiber optic acoustic sensing system for tracking a phase shift linearly over a wide range thereby allowing accurate tracking in the presence of temperature induced phase flucuation. In one embodiment, light from a laser is split and coupled into both legs of a fiber interferometer. One leg is phase modulated by the acoustic signal while the other leg is phase modulated by a first and a second piezoelectric cylinder modulators. The second modulator is driven at .omega..sub.m to effectively shift the acoustic information up in frequency into the sidebands of the carrier .omega..sub.m. The light signals in the two legs are combined, detected, cross-correlated with the carrier .omega..sub.m to produce an error signal, and then low pass filtered. This filtered error signal is fed back to control the first modulator. The first modulator keeps the interferometer locked in phase by effectively cancelling out the phase produced by temperature and acoustic pressure flucuations.

Abstract: A device in which a light source and a light receiving element are disposed at one side of a sheet transportation path and a reflecting member is disposed at the other side of the sheet transportation path so that a light ray emitted from the light source is reflected by the reflecting surface of the reflecting member and is caused to enter the light receiving element and any variation in the quantity of light entering the light receiving element is detected to thereby detect the presence of a sheet. The reflecting member is disposed such that the angle formed by the normal to the reflecting member with the surface of the sheet placed at the detection position is equal to or smaller than the critical angle at which total reflection is created on the surface of the sheet.

Abstract: An optical sensor for delivering error signals in order to control focusing of a lens on a movable recording medium or optical memory and more particularly a videodisk comprises a laser for producing a beam which is focused at a point S.sub.1. The divergent beam which proceeds from the point S.sub.1 is reflected from the face AB of a prism and is focused at a point S.sub.2. If the point S.sub.2 is located in the plane of the movable recording medium or so-called memory plane, the beam reflected from the memory plane is autocollimated and passes back through the focusing lens. A part of the beam enters the prism through the face AB, then emerges through the face AC and a circular light spot is formed in the plane corresponding to the circle of least confusion. If the point S.sub.2 is not located in the memory plane, the light spot is deformed and these deformations are detected by four juxtaposed cells placed in the plane of the circle of least confusion.

Abstract: An ignition equipment for light ignition thyristors for igniting a plurality of light ignition thyristors being connected in series with each other, which comprises an ignition circuit for generating a thyristor ignition electrical signal, a photoelectric conversion circuit receiving the thyristor ignition electrical signal to convert the same into a thyristor ignition light signal, a reverse voltage detecting means for detecting reverse voltage applied between an anode and cathode of each of the respective thyristors to transmit a reverse voltage detection signal, light guides for guiding the thyristor ignition light signal transmitted from the photoelectric conversion circuit to the thyristors, respectively, and light switches each inserted on the midway of each of the light guides and each interrupting the thyristor ignition light signal so as not to put the same into each of the thyristors while the reverse voltage is applied to each of the thyristors.

Abstract: A multielement-sensor measuring device having a number of sensor elements is provided with a switching means, a measurement means, a memory data extraction means and an offset and gain compensation means. In adjustment of the device prior to actual measurement, the sensor elements are sequentially switched over to the measurement means which measures their output and produces and forwards to the memory for storage offset and gain values according to the variation in offset and gain among the sensor elements. During operation, the stored offset and gain values are extracted from the memory by the data extraction means and used to control the offset and gain compensation means, whereby the outputs from the sensor elements are compensated so as to be made free from variation in offset and gain.

Abstract: A mirror actuator control system utilizing a wavefront sensor to determine the resulting angle error signal between the wavefront tilt angle and the mirror tilt angle. The resulting angle error signal is used to drive the actuator unit which controls the mirror tilt angle.

Abstract: The invention is directed to an X-Y co-ordinate detection system of the type which generates intersecting paths of radiation across a surface which may be, for example, a touch panel of the cathode ray tube type. Less expensive and more reliable operation is provided by developing the paths of radiation by use of radiation-emissive material disposed near at least one edge of the surface and excited by a flying spot of energy, such as an electron beam. In the preferred embodiment, strips of infrared emissive material are disposed on an internal surface of a cathode ray tube's panel and excited by overscanning the tube's electron beam to develop intersecting paths of infrared radiation across the tube's faceplate.

Abstract: A hot casting, freshly emerging from the mold, is inspected for any surface defects by a revolving line scan camera; the camera is disposed in an annular water-cooled, two-part housing having an inwardly directed annular gap covered by a sheet that revolves with the camera; the camera can look through a small gap of that sheet.