Abstract: A laser light, whose wavelength is to be measured, is introduced into an etalon, a concentric circular interference stripe derived from the etalon is irradiated onto a one-dimensional photodetector array and a diameter of the interference stripe is measured to measure the wavelength of the laser light. Alternatively, if a reference laser light of known wavelength is introduced into the etalon, as described above, a wavelength measurement of extremely high accuracy can be made without being affected by positional deviations of the optical system.

Abstract: An novel interferometric apparatus and method for measuring the topography of aspheric surfaces, without requiring any form of scanning or phase shifting. The apparatus and method of the present invention utilize a white-light interferometer, such as a white-light Twyman-Green interferometer, combined with a means for dispersing a polychromatic interference pattern, using a fiber-optic bundle and a disperser such as a prism for determining the monochromatic spectral intensities of the polychromatic interference pattern which intensities uniquely define the optical path differences or OPD between the surface under test and a reference surface such as a reference sphere. Consequently, the present invention comprises a "snapshot" approach to measuring aspheric surface topographies such as the human cornea, thereby obviating vibration sensitive scanning which would otherwise reduce the accuracy of the measurement.

Abstract: A wedge-type interferometer is disclosed that is supported three-dimensionally by a cast inner shell, which contains a readily removable optical cartridge supporting the fixed and movable wedge-shape prisms of the interferometer. The fixed prism is supported from one side of a centerpiece of the cartridge while the movable prism is supported from the other side of the centerpiece for linear, scanning movement. The cartridge may be mechanically and optically aligned prior to insertion into the inner shell, and is easily removed if additional adjustments are required. A first corner cube mirror is supported by a plate secured to one wall of the inner shell and is aligned by micropositioner adjustment in the X-axis. A second corner cube mirror is supported by a plate secured to another wall of the inner shell and is aligned by micropositioner adjustment in the Y-axis. After alignment, the micrometers are removed, and the inner shell may be mounted in an outer, hermetically-sealed casting.

Abstract: An apparatus for detecting flaws generated in the cut edges of cut glass plates is disclosed. The light emitted from a linear light source (11 and 21) and transmitted and reflected by a glass plate (1) is received by a one-dimensional imaging device (12 and 22), and the flaws in the cut edges of the glass plate are detected by a discriminator (13 and 24) based on the output voltage of the one-dimensional imaging device. The linear light source and the one-dimensional imaging device are disposed in such a manner that the longitudinal direction of the linear light source and the arranging direction of the imaging elements of the one-dimensional imaging device are parallel with each other, and that the longitudinal direction of the linear light source and the arranging direction of the imaging elements of the one-dimensional imaging device are oblique to the travelling direction of the glass plate on a plane parallel with the glass plate.

Abstract: The invention provides a laser interferometric measuring apparatus in which there is provided a corner-cube prism which includs a reflecting surface for selectively reflecting or transmitting a beam in accordance with the polarization condition of the beam and a transmitting surface for sending out a beam. A light source, a movable mirror, a fixed mirror, a detector and the corner-cube prism so arranged that the corner-cube prism receives a reference beam and a measuring beam from the light source through the reflecting surface, sends out the reference beam to the fixed mirror and the measuring beam to the movable mirror respectively through the transmitting surface, receives the reflected reference beam from the fixed mirror and the reflected measuring beam from the movable mirror through the transmitting surface and selectively sends out the reflected reference beam and the reflected measuring beam to the detector in accordance with their polarization condition through the reflecting surface.

Abstract: A three-dimensional displacement measurement apparatus includes a planar displacement measurement portion which measures a displacement of a measurement point on a surface of a measurement object in the direction of an X-Y plane, a vertical displacement measurement portion which measures a displacement of the surface in a vertical direction with respect to the X-Y plane, and a vertical displacement measurement position compensation portion that tracks a displacement of the measurement point on the X-Y plane.

Abstract: Two laser beams of different frequencies are combined to form a composite carrier beam of a frequency midway between those of the individual beams and modulated at the beat frequency between the individual beams. This composite beam can be used in a variety of ways, such as to irradiate a workpiece, the electro-optical frequency response characteristics of which are to be studied. By using an autocorollation technique the range of frequency over which these characteristics can be studied has for the first time been greatly expanded, well up into the terahertz range. Other applications of the equipment include the fine measurement of distances in the micrometer to meter range and secure digital transmission of data on a laser beam.

Abstract: The sensor system monitors solutes in a liquid stream by analyzing the amount of light absorbed in a liquid in a particular wavelength band. The sensor system is arranged for selectability of the type of fiber used for transmission and adjustability of the liquid gap length in the liquid so that individual installations can be arranged with optimum characteristics for sensing particular chemical species in solution by absorption spectroscopy.

Abstract: The present invention inhibits quenching of a laser following a radiation event by providing a radiation sensing arrangement connected to the discharge current control circuitry controlling the discharge current of the laser, for sensing a radiation event and for controlling the discharge current control circuitry in such a way that quenching of the laser for a predetermined amount of time after a radiation event is inhibited.

Abstract: Apparatus for measuring the value of the directional spectral hemispherical reflectance of the surface of a target when not engaging but being spaced from the target employs a hollow elongated member having a longitudinal axis and first and second opposite ends. The area of the first end is relatively large relative to that of the second end. The first end is open. The member has an inner chamber extending between the ends and has an inner surface adapted to reflect light falling within a specified wave band. The member when the apparatus is in use is positioned with the first end adjacent but spaced from a selected portion of the surface of the target. The longitudinal axis is oriented essentially normal to a region on the selected surface which would be engaged by a line coincident with the axis and sufficiently extended outwardly from the first end.

Abstract: In an apparatus for testing documents, the optical illuminating unit comprises at least one light guide provided with fluorescent substance for directing at least two light fractions of different wavelengths onto a common area of the document. The light fractions are switched on and off by the time-division multiplex method. Special switching regulators are provided for regulating not only the switch-on and switch-off operation of the illumination sources but also the brightness thereof.

Abstract: A differential fiber interferometer includes first and second optical fibers that pass through a coupler which has both input and output ends. A laser optically energizes a first one of the fibers and, via the coupler, the second fiber. A telescope lens system focuses optical beams from the first and second fibers onto an object and receives reflections therefrom for retrotransmission. The object is caused to oscillate at a first frequency so as to modulate the phase of the reflected optical beams. An optical sensor, positioned on the input side of the coupler, converts to electrical signals the reflected optical energy that appears on the second fiber. The reflected energy includes optical energies from both the first and second fibers. A first detector is responsive to the sensor's electrical outputs to produce a signal that is proportional to the differential phase between the reflected optical energies.

Abstract: A carriage is moved along a track by a motor connected in a first control loop to a carriage position sensor. The carriage carries a chassis which is coupled to it by a flexible linkage. The chassis carries an accelerometer connected by a second control loop independent of the first control loop to a linear actuator acting on the chassis and bearing on the carriage. The chassis carries a primary mirror fastened to it and a secondary mirror coupled to it by a piezo-electric actuator controlled via a third control loop by an optical path difference OPD error signal generated in the recombination station that includes the interferometer. The third control loop is desaturated by the first or second control loop, preferably by the second control loop. The preferably stellar interferometer may be on board a spacecraft.

Abstract: A subject position adjusting apparatus for use with an interferometer has a leveling stand disposed on a stationary stand of the interferometer. A leveling standard is stationary relative to and extends upright from the leveling stand. The leveling standard carries a subject stage for up and down movement in an axial direction of a light beam. A leveling mechanism is disposed between the stationary stand and the leveling stand. The leveling mechanism controls the angle of the leveling stand relative to a horizontal plane so as to level the leveling standard and make it parallel to the axial direction.

Abstract: Apparatus for monitoring, converting and calibrating the spectra displayed by a colored object, using wavelength dispersion provided by a variable wavelength filter. The apparatus may serve as a spectrophotometer, as a colorimeter, or as a spectroradiometer or other device that monitors and calibrates a light signal by decomposition of the signal into a wavelength distribution. The apparatus may also be used as part of a feedback network to monitor and correct colors displayed by a color monitor, color printer, color scanner or other similar peripheral device controlled by a computer that is part of the network.

Abstract: Symmetrical carrier frequency interferometer for length, distance and speed measurements with beam-deflecting and beam-splitting elements, as well as a fixed reference mirror and a movable measurement mirror. The optically active surfaces positioned downstream of a first polarization-splitting layer are arranged in mirror-symmetrical manner with respect to the latter. Upstream of a second polarization-splitting layer inclined by 45.degree. a .lambda./2 plate is located in one of the two beam paths and in the passage direction behind said layer are located the .lambda./4 plate, the fixed reference mirror and the movable measurement mirror. There is at least one reversing element in the reflection direction.

Abstract: A grazing incidence interferometer (1) includes a laser (10) and a beamsplitter (16) for splitting an output of the laser into a reference beam (B) and into a sample beam (A). A surface (18) to be examined is disposed at a first angle such that the sample beam is incident on and reflects from the surface at an angle of incidence other than normal, thereby providing a grazing incidence configuration. A beam combiner (22) combines the reference beam and the sample beam that reflects from the surface into a combined beam (C). An image plane (24) is disposed for receiving the combined beam such that an interference pattern is formed at the image plane. The image plane is disposed at a second angle to the combined beam, the second angle being selected to compensate for a reduction in an aspect ratio of the interference pattern that results from the surface being disposed at the first angle.

Abstract: An arrangement for measuring the reflection and/or transmission of an object comprises a frame 1, a carrier 7 for the object, a radiation source 15 and a detector unit. The detector unit, which comprises one or more radiation-sensitive detectors 17A, 17B may be arranged on a holder 13 which is pivotable about a pivotal axis 13a. A slide 5, which is movable parallel to the pivotal axis, may be provided for moving the carrier and the detector unit rectilinearly towards and away from one another.

Abstract: In an interferential measurement device for at least one direction of measurement for measuring the relative position of objects, the collimated light beam bundle emanating from a light source is split into three diffraction beams in the at least one direction of measurement at a scanning grid. These three diffraction beams are divided into eight diffraction beams at a cross grid of a material measure and in turn come to interference at a scanning grid under renewed diffraction. The resultant diffraction beams fall on detectors for the generation of measured positional values for the at least one direction of measurement. The cross grid of the scale extends diagonally to the at least one direction of measurement and has an effective grid constant de in the direction of measurement, which agrees with the grid constant d of the scanning grid.

Abstract: This invention tests a vehicle, such as an aircraft, using nondestructive interferometry. An interferometer detects movements in the vehicle surface due to stress. One applies such stress by pressurizing the vehicle. In one embodiment, a hood housing the interferometer attaches to the vehicle surface with the aid of a vacuum. One can vary the pressure in the vehicle in various ways, while monitoring the interferometer for signs of defects in the structure behind the surface. The invention also includes an arrangement for substantially automating the analysis. For example, one can automatically position the interferometer according to position information received from appropriate sensors, in combination with stored information about the structure of the vehicle. One preferably uses a real-time interferometer, such as an electronic shearography camera, in the present invention. One can quickly determine the location of defects by observing fringes on a video monitor.