Abstract: A method of optically testing the lateral dimensions of a pattern of material disposed on a substrate comprises applying the material to both the main area of the substrate and a test area on the same substrate, and selectively removing the material from both areas on the substrate simultaneously to form respectively the pattern on the main area and a diffraction grating on the test area. The diffraction grating is exposed to a beam of light, and the intensity of two of the diffracted beams is measured to obtain a ratio signal (I.sub.2 /I.sub.1), which is then utilized to determine the lateral dimensional tolerance of the integrated circuit pattern.

Abstract: A device which measures the mutual coherence function of a laser beam. The device includes: a screen 1 in which openings 3 to 11 are disposed on the path of the beam 2 and allow pencils of light 19, 29 and 34 to pass; an interferometer constituted by an optical plate 13, a dihedron 14 and a mirror 21; a phase modulator 22 disposed on a branch of the interferometer; receivers 23 to 27 which receive the pencils of light 20 and 33 which emerge from the interferometer; and a processing circuit 36. Application to the analysis of a laser beam.

Abstract: A nondestructive dynamic controller for thermoplastic development is disclosed. The dynamic controller monitors the development of a hologram, without altering the charge pattern on the recording medium that is required for the development. The dynamic controller determines when optimum deformation has occurred in the developing recording medium and provides a signal which is used to shut off the thermal input used in the development.

Abstract: A method and apparatus for mutually adjusting the positioning of planar, generally transparent components such as for example, small liquid-crystal plates. The plates are provided with marks specially structured to diffract incident collimated light, in a shape or direction which is characteristic for each plate. By means of a convergent lens, characteristic diffraction images produced by passing light through the marks are depicted on a detector located in the image plane of the convergent lens. The respective characteristic images of the marks are stopped down individually by means of a diaphragm located in the lens focal plane. The diaphragm can periodically be closed partially, so that control signals for the electronic displacement of each plate can be derived individually from the particular positions of the images of the marks on the detector, corresponding to the positions of the plates.

Abstract: The invention relates to an optical correlator comprising an optical system for imaging an object space, a spatial frequency filter disposed in or close by the image plane, and at least one photoelectric detector assigned to said spatial frequency filter. According to the invention the spatial frequency filter is a raster, the structures of which extend in the direction of the perspective vanishing lines of the image of the object space and/or perpendicularly to at least one of said vanishing lines. The size of the structure elements and/or the distance between the elements constituting the raster structure are chosen according to the distortion of the perspective image.

Abstract: First and second plates are formed with like periodic patterns. A laser beam illuminates the second plate through the alignment marks of the first plate to provide a pair of diffracted beams that are detected with alignment being indicated when the beams are of the same intensity.

Abstract: Defect detection apparatus provides a moving light beam which illuminates the surface of a rotating grooved disc with a light spot spanning a plurality of convolutions of the groove. The beam is translated to rapidly scan the grooved surfaces in a radial pattern. The structure of the groove convolutions, absent any defects, diffracts the incident beam producing a plurality of reflected beams. A first lens, provided in the path of the reflected beams, provides, in a focal plane thereof, a Fourier transformation of the light amplitude data of the respective reflected beams. A second lens, provided in the diffracted beam path downstream of the first lens, provides at the surface of a photodetector, an inverse Fourier transformation which is an image of the scanning spot. Blocking means, placed in the focal plane of the first lens intercept the reflected beams when defect-free groove regions are illuminated, to prevent the conversion of light energy to electric energy by the photodetector.

Abstract: Apparatus provides an incident light beam which illuminates the surface of a grooveddisc, having signal elements recorded therein in the form of a succession of spaced apart depressions, with a light spot that spans a plurality of convolutions of the groove. The structure of the grooved convolutions serves as a diffraction grating which reflects the incident light beam into a first plurality of substantially coplanar diverging beams of light. The signal elements also serve as a diffraction grating which reflects the incident light beam into a second plurality of diverging beams of light. Photodetectors, respectively positioned to intercept several of the reflected beams provide outputs corresponding to the light power in the respective reflected beams. Circuits are provided for directly deriving from the photodetector outputs respective estimations of both groove and signal element depths in the region illuminated by the light spot.

Abstract: An electro-optical sensor is described which provides an output for precisely locating the centers of interference fringes in either a real-time interference pattern or an interferogram. By scanning the fringe pattern either by moving the fringe pattern, by effectively moving the photoelectric sensor, or both, the centers of the fringes can be rapidly and precisely determined from the first derive of the output of the photodetector.

Abstract: A light scanning system is described, comprising a circular disk having a plurality of zone-type lenses, where each of the zone-type lenses converges an incoming light beam toward a corresponding focal point, and when moving said circular disk and said incoming light beam relatively each other, said focal point scans object to be scanned in a scanning direction.

Abstract: Groove depth estimation apparatus provides an incident light beam which illuminates the surface of a grooved disc with a light spot that spans a plurality of convolutions of the groove. The structure of the groove convolutions serves as a diffraction grating which reflects the incident light beam into a plurality of diverging beams of light. A photodetector provides measurements of the light power in the respective reflected beams. Calculator circuits are provided for deriving from the photodetector measurements estimation of the average groove depth in the region illuminated by the light spot.

Abstract: A means of probing a biological cell sample with a optical source to determine the characteristics of the cell image by way of measuring parameters from its two dimensional Fourier transform. These techniques lead to a method of measuring discriminating parameters for cell classification.

Abstract: A method and apparatus are provided for storing and reading authenticating information which is recorded on a carrier comprising at least one diffraction screen for modifying the path of a beam from an optical reading apparatus consisting of a light-source and a light-receiver. A method is provided for producing an information carrier having at least one diffraction screen.

Abstract: The invention relates to an optical correlator comprising an optical system for imaging an object space, a spatial frequency filter disposed in or close by the image plane, and at least one photoelectric detector assigned to said spatial frequency filter. According to the invention the spatial frequency filter is a raster, the structures of which extend in the direction of the perspective vanishing lines of the image of the object space and/or perpendicularly to at least one of said vanishing lines. The size of the structure elements and/or the distance between the elements constituting the raster structure are chosen according to the distortion of the perspective image.

Abstract: A signature is holographically recorded for correlation and parallel procing against a large library of signatures. A transient electrical signal produces a pressure wave in an optical wavefront modulator where it is frozen in position by a picosecond laser. The modulated wavefront is made to interfere at a hologram plane with a reference wavefront which is converging to a focal point behind the hologram plane. Because the holograms are of the Fresnel type, the hologram plane may be partitioned off and a library of signatures may be recorded on the same hologram plane and addressed simultaneously. After processing, the reference wave is removed and the optical wavefront modulator illuminated by a continuous wave coherent source. If a signature, recorded on the hologram, is placed in the optical wavefront modulator, then the reference wave for that hologram is reconstructed and detected to identify that signature.

Abstract: Direct spatial Fourier power spectra of optical images are obtained by maulating either the image focused onto a photosensitive charge coupled device (CCD) or the readout from the CCD.

Abstract: Method and apparatus for determining the wave number of optical spectrum radiation, particularly for use in controlling lasers. Two parts of a beam provided by a source to be monitored, particularly a laser, are directed to two double-wave interferometers. The differences of the optical path lengths .delta. of the interferometers are assigned a difference of .lambda./4 which corresponds to a phase difference of .pi./2. The two optical output signals emerging from the interferometers are converted into sinusoidal electrical waves in quadrature as a function of the wave number .sigma. = 1/.lambda. of the laser and the period 1/.delta. of the two sinusoidal electrical waves. The electrical waves are processed in suitable circuitry to obtain a modulo value 1/.delta. of the wave number. These steps are repeated for different values of .delta. so as to progressively eliminate uncertainty in the value of the wave number.

Abstract: An improved apparatus and method for generating the two-dimensional filtered back-projected image of a slice of an object. In accordance with the invention there is provided a photodetector means and illuminating means directed toward the photodetector means. A carrier means is disposed between the illuminating means and the photodetector means, the carrier means having a plurality of substantially parallel elongated projections on the surface thereof. Each projection has an optical characteristic (transmissivity or reflectivity) representing the density characteristic of the slice of the object as measured at a particular relative rotational angle. A mask means is disposed between the illuminating means and the photodetector, the mask means comprising a plurality of cycles of a substantially sinusoidally shaped pattern of varying amplitude. Means are provided for moving the carrier means and the mask means with respect to each other.

Abstract: An instrument for measuring various and sundry parameters that are analog to the aberrations that may exist in holographic lenses and other energy diffraction apparatus is disclosed as containing: a laser energy source; a pair of masks for controlling precisely the path of the light from said laser energy source, so that it may be used as a reference parameter; a rotatable mounting table for holding the holographic lens being tested in an appropriate position in the path of said reference laser light path; a microscope positioned to receive predetermined laser light rays that have been diffracted by the holographic lens being tested; indicia to measure the X, Y and Z axes distances between that point on the holographic lens being tested where the aforesaid laser light path passes therethrough and a given point position on or with respect to said microscope; and a support bench upon which all of the aforesaid elements may be mounted, so that their respective relative positions may be controlled in such manner

Abstract: Apparatus to automatically analyze stereoscopic images comprising the determination of the maximum degree of correlation between two similar images of the same object projected by two objectives, for instance in a rangefinder, wherein the two images are superimposed on one or two spatial frequency filters identical in their structures, and wherein the particular generated superimposition signal, is preferably applied to a particular photoelectric detector and wherein the output signals from the latter are used for display and/or control purposes. The apparatus is improved by a system (20,20',21,21',22-25; 30-34) for generating a reference beam indicating mechanical changes affecting the image position of at least one of the measuring beams, at least one photoelectric detector (28,29;40) being associated with the one reference beam, the output signals from the one detector corresponding to the mechanical changes being used to display and/or correct the changes or the effects of same.

Abstract: First and second pairs of mirrors are oriented to intercept first and second regions respectively of a diffraction pattern and deflect these regions to individual detectors so that simultaneous analysis of the regions of the diffraction pattern can be carried out. The pairs of mirrors can be spaced along the optical axis in a manner to provide focused regions of the diffraction pattern at the detectors wherein the diffraction pattern itself is imaged at two spaced focal planes resulting from astigmatic conditions. The physical arrangement not only overcomes problems introduced by astigmatism but also permits practical physical positioning of individual photo-diode arrays such that simultaneous processing of the regions in the diffraction pattern can be carried out.

Abstract: Parameters of a clad optical fiber are measured by irradiating the fiber with a laser beam to generate a scattering pattern. Measurements are made of fringes and modulations in the scattering pattern and these measurements are translated into such parameters as the diameter of the core and cladding thickness as well as the deviation from concentricity of the core of the clad optical fiber.

Abstract: An apparatus and method for counting the number of objects-of-interest present in a selected sample by scanning the sample with a rotating reticle of preselected design to measure the spatial frequency components in the field-of-view, which components are definitive of the number of objects-of-interest present. The spacing within the reticle pattern determines the size of the objects that will be counted. The invention has significant application as a means for counting bone marrow granulocyte precursor colonies in the detection and treatment of leukemia.

Abstract: A scanning microdensitometer comprising complementary sampling aperture components which produce positive and negative contributions to the sample measurements.

Abstract: Defect detection apparatus, for optically inspecting a spiral groove of a video disc record, directs a coherent light beam at the grooved surface of the disc. The incident beam, focused at a point beyond the disc surface, illuminates the grooved surface with a light spot that spans a plurality of convolutions of the groove. Relative motion is established between the disc surface and the incident beam in a manner causing the illuminating spot to rapidly scan the groove surfaces in a coarse spiral pattern. The structure of the illuminated groove convolutions, absent any defects, serves as a diffraction grating for diffracting the light into an undeviated zero diffraction order cone of light that converges at a first location in a plane spaced from the disc surface and into deviated higher diffraction order cones of light that converge at additional locations in said plane separated from the first location.

Abstract: Method and apparatus are disclosed for determining a parameter of a clad optical fiber from the scattering angle at the maximum of a modulation component in a forward far-field scattering pattern produced by directing a monochromatic coherent light beam at the fiber. One such parameter is the ratio between core radius and cladding radius.

Abstract: A technique and apparatus for two dimensional pattern analysis utilizing a transform of the pattern enables the extraction of desired pattern information by means of spatial filtering in accordance with known human visual system processing. Two dimensional spatial frequencies resulting from the transform are acted on by either anisotropic or uniquely used conventional filters to extract one, two and three dimensional pattern information from spatial frequency subsets to determine general form, edge, texture and depth information for detection, identification and classification of objects in simple or complex scenes.

Abstract: A fingerprint optical sensor terminal is provided for use in the real time recording of an impression of a fingerprint pattern, the human finger being placed for the purpose at an input window surface of the sensor terminal. The sensor terminal provides precise angular and positional alignment of the finger and affords the immediate recognition of the presence of a finger that would produce a poor impression, permitting prompt corrective action by the operator. The sensor terminal also permits the making of an impression of a wide area of the finger, thus providing increased discrimination and accuracy of print identification with increased economy.

Abstract: A spot of collimated monochromatic radiation is applied to a semiconductor wafer to obtain a diffraction pattern from two edges within an area, which is the size of the spot, on the wafer. The diffraction pattern is reflected to a photodiode array wherein the light intensity of the diffraction pattern at each of a plurality of positions is obtained. Each of the photodiodes is scanned separately for the same period of time to determine the light intensity at its location. The distance between the zero intensity positions on the photodiode array is determined very precisely and utilized with the wavelength of a laser, which supplies the spot of collimated monochromatic radiation, and the effective focal length of the lens system, which images the diffraction pattern to the photodiode array, to calculate the linear distance between the edges.

Abstract: The average aperture width in a small area of an apertured member, such as a shadow mask for a cathode ray tube, is determined by passing a beam of substantially monochromatic light through an area of the member to form an interference pattern, detecting the intensities of at least two light fringes of the interference pattern, generating electrical signals which are representative of the detected intensities and then deriving the average width of apertures in the lit area of the members from the generated signals.

Abstract: Relatively large hologram storage plates, e.g., those storing a large number of discrete entries such as character definitions for a large character set, comprise an array of mini-holograms arranged in different memory plate sections.A different photodiode array is associated with each hologram plate section (for efficiency, some elements of different diode arrays may be common). When the stored contents of any mini-hologram are interrogated by a coherent light beam, the stored information is derived via the associated photodiode array and converged (as by OR logic) to memory output terminals.

Abstract: Rather than counting nulls in the diffraction pattern generated by a very narrow line or gap in order to measure its width, the diffraction pattern is optically detected and converted to an analog electrical signal constituting a function of the detected intensities in the diffraction pattern. This function is then converted to a digital form, stored, and then passed to a computer electrically computing the Fourier transform to provide an autocorrelation wave form. This wave form is then plotted in an orthogonal X-Y coordinate system and the break point or extension of a linear segment of the autocorrelation curve relative to the X-axis used to provide a precise measurement of the given width.

Abstract: A holographic optical memory utilizes an optical heterodyne technique to significantly increase the signal-to-noise ratio during the readout stage of operation. A light source provides a coherent light beam which is split into a readout beam and a local oscillator beam. The readout beam is directed to one of the holograms stored in the memory medium and a portion of the readout beam is diffracted by the hologram to form a reconstructed image of the bit pattern stored in the hologram at the reconstructed image plane. The local oscillator beam is superimposed with the diffracted portion of the readout beam. An optical frequency translator is positioned in either the readout beam or the local oscillator beam to cause the beams to have different optical frequencies. Therefore, when the two beams are superimposed, a beat frequency signal is produced. An array of detectors is positioned at the reconstructed image plane to receive the superimposed beams.