Using Fourier Transform Spatial Filtering Patents (Class 359/559)
  • Patent number: 5644429
    Abstract: A method of forming 2 dimensional image of a translucent object in or behind a turbid medium. In one embodiment, the method comprises the steps of illuminating the translucent object through one side of the turbid medium with an ultrafast pulse of light, the light emergent from the opposite side of the turbid medium consisting of a ballistic component, a snake-like component and a diffuse component. The emergent light is then temporally and spatially gated to preferentially pass the ballistic component and the snake-like component. Preferably, the temporal and spatial gating is achieved by positioning the Kerr cell of an optical Kerr gate at the 2F spectral plane of a 4F Kerr-Fourier imaging system. At the appropriate time, that portion of the Kerr cell located at the focal point of the 2F spectral plane is gated open, allowing predominantly ballistic and snake-like components of the transilluminated light to pass therethrough.
    Type: Grant
    Filed: May 29, 1996
    Date of Patent: July 1, 1997
    Assignee: Research Foundation of City College of New York
    Inventors: Robert R. Alfano, Ping-Pei Ho, Xiangchun Liang
  • Patent number: 5638211
    Abstract: A method and apparatus for transferring a fine pattern (12) on a mask (11) onto a substrate (17) by a projection exposure apparatus including an illumination optical system (1-10) for irradiating an illuminating light on the mask (11), and a projection optical system (13) for projecting an image of the fine pattern (12) on the illuminated mask onto the substrate (17). The illuminating light is irradiated at least in the form of a pair of light beams opposedly inclined with respect to the mask through a pair of transparent windows (6a, 6b) of a spatial filter (6) whereby either one of the .+-.
    Type: Grant
    Filed: June 10, 1994
    Date of Patent: June 10, 1997
    Assignee: Nikon Corporation
    Inventor: Naomasa Shiraishi
  • Patent number: 5629802
    Abstract: A spatial light modulator has a plurality of pairs of input and reference images recorded upon a plurality of sub-areas thereof. Each sub-area is illuminated with an associated point source of light which is produced by illuminating a diffraction grating with coherent light. A Fourier transform lens produces a joint transform of each pair of input and reference images which can be detected by a CCD camera.
    Type: Grant
    Filed: January 5, 1995
    Date of Patent: May 13, 1997
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventor: Natalie Clark
  • Patent number: 5627678
    Abstract: A Fourier transform optical apparatus for optically Fourier transforming an input image includes a spatial light modulator for displaying an input image, a light source for irradiating the input image on the spatial light modulator, a first convex lens and a first concave lens arranged near the spatial light modulator and a second convex lens arranged at the composite focal plane of the first convex lens and first concave lens. The respective focal lengths of these three lenses are determined to satisfy conditions such that a light ray passing an intersection of the spatial light modulator and an optical axis of the Fourier transform optical apparatus becomes a light ray parallel to the optical axis after passing the second convex lens and a light ray incident to the first convex lens in parallel to the optical axis is focused at the composite focal point of the first convex lens, first concave lens and the second convex lens.
    Type: Grant
    Filed: March 15, 1995
    Date of Patent: May 6, 1997
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Kanji Nishii, Kenji Takamoto, Masami Ito, Atsushi Fukui
  • Patent number: 5627847
    Abstract: Method for making a distortion-compensating phase-adjustment element for a laser. One type of distortion to be compensated for is heat distortion. Also described is a method for making a custom phase-conjugating diffractive mirror for a laser resonator comprising the steps of: (a) choosing a specified beam mode profile a.sub.1 (x,y), (b) calculating the mode profile b(x',y') which is a value of the specified beam a.sub.1 (x,y) that is propagated to the reflection surface of the diffractive mirror and (c) calculating mirror reflectance t(x',y') which reflects phase conjugate of b(x',y') and corrects for distortions such as heat. A method for fabricating such a mirror is shown. Another aspect of the invention is the addition of a phase adjusting element into a laser resonator, and compensating for the addition of a phase adjusting element in the design of other phase-adjusting elements such as the mirrors and correcting for distortions such as heat.
    Type: Grant
    Filed: May 4, 1995
    Date of Patent: May 6, 1997
    Assignee: Regents of the University of Minnesota
    Inventor: James R. Leger
  • Patent number: 5619596
    Abstract: An object of the invention is to provide a method and a apparatus for optical pattern recognition capable of accurately comparing and identifying a reference image accurately at a real-time even when the input image rotates or its size changes by being compared with a reference image that is a desirous target. The method and apparatus comprise the processes of; steps (6, 11) for independently obtaining a lower-frequency component and a higher-frequency component from a joint Fourier transform image 5 of the reference image 4 and the input image 3; steps (10, 15) for calculating correlation coefficients respectively from the lower-frequency component and the higher-frequency component; step (16) for obtaining a ratio of the respective correlation coefficients; and step (19) for identifying and comparing a correlation coefficient ratio of the two same reference images to be required with a correlation coefficient ratio obtained from step (16).
    Type: Grant
    Filed: October 6, 1993
    Date of Patent: April 8, 1997
    Assignees: Seiko Instruments Inc., Sumitomo Cement Co. Ltd.
    Inventors: Tadao Iwaki, Nobuyuki Kasama, Shuhei Yamamoto, Toshiharu Takesue, Yasuhiro Takemura
  • Patent number: 5606435
    Abstract: The fiber optic-based correlating and sensing system (the System) utilizes length of optical fiber through which the object beam travels prior to being incident on the holographic plate. First, a matched filter is created on the holographic plate of the initial condition of the environment. Then when the plate is re-placed in its original position in the System and the reference beam is blocked from reaching the plate, a correlation peak appears as the object beam passes through the holographic plate. To use the System as a correlator, the object beam is transmitted through an input scene prior to its travel through the optical fiber. The changes in the input scene from the initial scene causes broadening of the shape of and degradation of intensity of the correlation peak. To use the System as a sensor, the object beam travels through the optical fiber acquiring information regarding the environment surrounding the fiber, such as pressure, temperature, sound, electric and magnetic fields.
    Type: Grant
    Filed: December 22, 1995
    Date of Patent: February 25, 1997
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Amy S. Kransteuber, Don A. Gregory
  • Patent number: 5604634
    Abstract: A fully parallel, self-aligning, nonlinear and all optical joint transform correlator utilizes a photorefractive four wave mixer positioned to record the joint transform spectrum interfering with a reference beam together with a phase conjugator which directs a readout beam at the four wave mixer. The signal readout of the mixer is Fourier transformed and can be recorded upon an image sensor to detect the correlation spots indicating the degree of similarity of the two input images.
    Type: Grant
    Filed: September 20, 1993
    Date of Patent: February 18, 1997
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Jihad Khoury, Charles L. Woods
  • Patent number: 5594586
    Abstract: Limiting quadratic processing and compansion in photorefractive two beam coupling is disclosed. Two-beam coupling in photorefractive barium titanate employs the imaged intensity of the signal to amplify the reference beam while maintaining the phase of the reference beam. The phase distorted signal beam is converted to that of the controlled phase of the reference beam. The high pump limit of amplification in this two-beam coupling device produces an amplitude compressed output to reduce multiplicative noise. Lost contrast of the image is thereafter restored. Beam clean-up of a non-intelligence bearing beam can be carried out by a similar process; a low pass filter consisting of a pinhole plate can be used in place of the second photorefractive crystal in the Fourier plane and only the planar wavefront portion will pass through the pinhole and may be collimated by a lens to provide a cleaned planar output beam.
    Type: Grant
    Filed: May 2, 1994
    Date of Patent: January 14, 1997
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Jehad Khoury, Charles L. Woods, Mark Cronin-Golomb, Jack Fu
  • Patent number: 5587829
    Abstract: A signal filter, and method of signal filtering, in which an optical signal s spatially dispersed according to frequency, and undesired frequencies blocked out. In an embodiment, a Bragg cell receives a (typically microwave) signal, and transduces it to an acoustic signal. A light source, e.g. a laser diode, directs light through the acoustic signal in a known manner so as to produce an optical output which is spatially dispersed according to frequency. A programmable spatial light modulator blocks out unwanted frequency components. Upon removal of the optical carrier, e.g. by heterodyning the spatial light modulator's output with a reference signal from the light source, the components can be recombined into a resultant filtered signal. The invention can be used as a repeater, a military electronic countermeasure, in environments which have large amounts of electromagnetic clutter but in which one does not want the clutter repeated.
    Type: Grant
    Filed: August 29, 1994
    Date of Patent: December 24, 1996
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Edward M. Alexander, Anthony E. Spezio
  • Patent number: 5581383
    Abstract: An arrangement for optical autocorrelation of laser speckle photography (LSP) photographs or particle image velocimetry (PIV) photographs using optical Fourier transforms is disclosed. The object of providing an electro-optical arrangement for optical correlation of LSP film recordings and PIV film recordings which is simple to produce and accurate is met by using an optically addressable liquid crystal SLM (spatial light modulator) for producing the Young's fringe patterns which contains a uniaxial double-refracting liquid crystal layer and is read out with linearly polarized light of a laser light source, wherein the polarization direction of the laser light source on the readout side coincides with the extraordinary semi-axis of the refractive index ellipsoid of the liquid crystal layer.
    Type: Grant
    Filed: February 28, 1995
    Date of Patent: December 3, 1996
    Assignee: Jenoptik Technologie GmbH
    Inventors: Frank Reichel, Ernst Gaertner
  • Patent number: 5579161
    Abstract: An image display apparatus comprises an image display unit capable of producing and displaying not an image itself but a Fourier-transform image of the image, and a light transmission unit for focusing the Fourier-transform image produced and displayed on the image display unit on a pupil face of an observer's eye and producing an original image on the retina of the eye. The light transmission unit includes a lens and an eye lens such that an image-side focal position of the lens coincides with an object-side focal position of the eye lens. A mask is situated at the object-side focal position of the eye lens to determine the range and shape of a visual field. The image display unit is situated at an image-side focal position of the lens, and the pupil face of the observer's eye is alinged at an image-side focal position of the eye lens.
    Type: Grant
    Filed: November 9, 1993
    Date of Patent: November 26, 1996
    Assignee: Olympus Optical Co., Ltd.
    Inventor: Nobutoshi Sekiguchi
  • Patent number: 5555128
    Abstract: An object beam is passed through an aberrating medium to produce a diffraction distorted image therein, which is imaged upon a spatial light modulator. A probe beam measures the phase aberrated wavefront within the aberrating medium and is used to produce an interference pattern which is employed to produce phase encoding signals to be fed back to the spatial light modulator for compensating in part for the phase distortion of the phase aberrated wavefront. The result is an output image having a substantially reduced degree of distortion.
    Type: Grant
    Filed: October 4, 1994
    Date of Patent: September 10, 1996
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Jehad Khoury, Charles L. Woods, Jack Fu
  • Patent number: 5546225
    Abstract: In a method of manufacturing a lithographic mask by generating a plurality of light-shielding or transparent pattern elements with respect to a predetermined energy beam on a predetermined original plate on the basis of design data defining shapes and layout of the respective pattern elements, it is determined whether an outer edge of a specific pattern element of a predetermined width or less in the plurality of pattern elements is spaced apart from other pattern elements adjacent thereto by a predetermined distance or more. The design data is corrected so as to complementarily expand the outer edge portion of the specific pattern element outward from other outer edge portions by a small amount when the outer edge portion of the specific pattern element is spaced apart from the other pattern elements by the predetermined distance or more. The plurality of pattern elements are generated on the original plate on the basis of the corrected design data.
    Type: Grant
    Filed: May 31, 1995
    Date of Patent: August 13, 1996
    Assignee: Nikon Corporation
    Inventor: Naomasa Shiraishi
  • Patent number: 5528389
    Abstract: A serial-to-parallel and parallel-to-serial conversion apparatus and method are disclosed to convert optical pulse data into temporally multiplexed ultra-fast optical pulses, and vice versa, using Fourier holographic transform techniques. In a first embodiment, optical pattern data is converted from a serial temporal-domain optical input signal to an output signal having parallel bits by recording a spectral hologram of the pulse data and reading it out with a continuous-wave (cw) laser. In a second embodiment, signals representing input bits in parallel may be optically multiplexed in the time domain, so that a single optical fiber may carry such signals without the electronic processing necessary in conventional switching multiplexers.
    Type: Grant
    Filed: November 14, 1994
    Date of Patent: June 18, 1996
    Assignee: AT&T Corp.
    Inventor: Martin C. Nuss
  • Patent number: 5519533
    Abstract: There is reproduced a three-dimensional image in which there is no dimness or no cross talk and which is light and high in resolution, by a three-dimensional information reproducing apparatus comprising a liquid crystal panel for displaying a discrete Fourier transform image, a light source array which is disposed to the rear of the liquid crystal panel and which emits parallel light, and a synchronous control device for switching, with time division, the discrete Fourier transform image that is displayed in the liquid crystal panel and also an angle of the parallel light that is emitted from the source light array.
    Type: Grant
    Filed: February 28, 1995
    Date of Patent: May 21, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Toshio Nomura, Masayuki Katagiri, Noritoshi Kako
  • Patent number: 5515183
    Abstract: A real-time holography system includes a matrix liquid crystal display, as used in a liquid-crystal television set, for producing a hologram. An image of an interference-fringe pattern caused by an object light wave and a reference light wave is converted into a video signal by a CCD camera, and the image of the pattern is reproduced on the display on the basis of the video signal. Therefore, a three-dimensional image can be reconstructed in real-time by making a reference light wave on the display.
    Type: Grant
    Filed: March 15, 1994
    Date of Patent: May 7, 1996
    Assignee: Citizen Watch Co., Ltd.
    Inventor: Nobuyuki Hashimoto
  • Patent number: 5497253
    Abstract: A pattern recognition apparatus and a method for operating same. The apparatus includes a volume holographic medium (4) having a plurality of Fourier-space volume holograms representing pattern templates stored within. The apparatus further includes a spatial light modulator (1) and a phase encoder (2). The phase encoder has an output optically coupled to the medium by a first Fourier transform lens (3). The spatial light modulator spatially modulates a spatially uniform laser beam (7) in accordance with an unknown pattern. The two-dimensional phase encoder causes the spatially modulated laser beam to be spatially distributed prior to application to the medium. The apparatus also includes a detector (6, 11) having an input optically coupled by a second Fourier transform lens (5) means to an angular spectrum of plane waves generated by the medium in response to the output of the spatial modulator, phase encoder, and first Fourier lens.
    Type: Grant
    Filed: July 30, 1993
    Date of Patent: March 5, 1996
    Assignee: Northrop Grumman Corporation
    Inventors: Harold M. Stoll, James J. Reis
  • Patent number: 5493444
    Abstract: An all-optical nonlinear joint transform correlator has been implemented for the first time without using a spatial light modulator and digital processing in the Fourier plane. The correlator utilizes energy transfer from two-beam coupling in the Fourier plane. A compressional nonlinearity in the hard-clipped regime is implemented by pumping a weak plane wave with the intense joint spectrum of the reference and signal images. Operation of this device rivals or exceeds that of the phase-only filter for detecting objects in cluttered noise. Experimental results are compared with both plane wave and beam propagation simulations.
    Type: Grant
    Filed: April 28, 1994
    Date of Patent: February 20, 1996
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Jehad Khoury, Charles L. Woods, Peter D. Gianino, Mark Cronin-Golomb
  • Patent number: 5485312
    Abstract: A method of verifying the authenticity of an object is disclosed preferrably employing a joint transform coherent optical processor. An unreadable and hence non-counterfeitable phase mask is coupled to the object and the optical processor compares the phase mask with a reference phase mask having the same phase code thereon. The processor produces a correlation spot having an intensity which exceeds a given level if the phase mask is genuine. A highly secure ID or credit card also carries a fingerprint bonded to the phase mask, and the fingerprint on the card is compared to a reference fingerprint of the card holder for added security.
    Type: Grant
    Filed: September 14, 1993
    Date of Patent: January 16, 1996
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Joseph L. Horner, Bahram Javidi, John F. Walkup
  • Patent number: 5477382
    Abstract: A system and method of optical correlation that avoids bias level terms in the optical correlation output. In the system and method, two coherent polarized component beams having frequencies f.sub.1 and f.sub.2 are derived from a light source. Portions of these component beams are converted to a reference electrical signal having a frequency .DELTA.f=f.sub.2 -f.sub.1. The sum f.sub.1 +f.sub.2 of the component beams is correlated under the control of a multiple of the reference electrical signal. The Fourier transform of the amplitude of the correlated light is projected and detected on a detection plane.
    Type: Grant
    Filed: August 5, 1994
    Date of Patent: December 19, 1995
    Assignee: Northrop Grumman Corporation
    Inventor: Benjamin J. Pernick
  • Patent number: 5459602
    Abstract: A micro-optical shutter array (92, 102) having a number of tiny shutters (10), which revolve so as to intermittently block light from a via (12), and which may be operated in either a stepping or continuous motion. The array (92, 102) may be batch manufactured using integrated circuit fabrication techniques. For each shutter, a via (12) is etched through a substrate (11). A rotor (13, 43, 53, 63) with at least one opening is fabricated over the via (12), such that as the rotor (13, 43, 53, 63) turns, radiation transmitted through the via (12) is selectively blocked or not blocked.
    Type: Grant
    Filed: October 29, 1993
    Date of Patent: October 17, 1995
    Assignee: Texas Instruments
    Inventor: Jeffrey B. Sampsell
  • Patent number: 5452002
    Abstract: A video color encoding apparatus (10 ) having a lens (14) for focusing an image (16) on an imaging element (20). The imaging element (20) has a monochromatic CCD imager (22) and a tricolor grating assembly (26) interposed between the CCD imager (22) and the lens (14) such that the image (16) is spatially and spectrally modulated onto the monochromatic CCD imager (22) in data compressed format. The image (16) can be reconstructed using conventional optical techniques with an optical reconstruction apparatus (46) or, alternatively, using mathematical means by a digital computer (42) to be displayed directly on a computer screen (54).
    Type: Grant
    Filed: July 27, 1993
    Date of Patent: September 19, 1995
    Inventors: Guo-Guang Mu, Zhi-Liang Fang, Fu-Lai Liu, Ming-Ze Lu
  • Patent number: 5452137
    Abstract: In an optical correlator system having reflective and transmissive optical components positioned along a folded and segmented optical axis or path, one or more optical path extenders are provided for selected optical path segments that require operative path length adjustment so that an electromagnetic radiation beam, which traverses the folded optical path with selected information imparted into and detected from the beam, can be imaged upon a defined and maximum usable area or region both on the reflective components and on an end detector component.
    Type: Grant
    Filed: April 5, 1993
    Date of Patent: September 19, 1995
    Assignee: Litton Systems Inc.
    Inventor: John R. Lucas
  • Patent number: 5440426
    Abstract: Method and apparatus for forming an image of an object by optical projection with a focusing system comprising the steps of collimating a set of at least two mutually incoherent light beams from the light source to fall on the object from directions that makes the non-diffracted components intersect the aperture stop at a set of points that are distributed over the surface of the stop, attenuating in a spatial filter the zero diffraction order of each beam relative to diffraction orders diffracted in directions towards the centre of the aperture stop, and adding the images formed by the light beams.
    Type: Grant
    Filed: July 13, 1994
    Date of Patent: August 8, 1995
    Inventor: Erland T. Sandstrom
  • Patent number: 5438440
    Abstract: A technique for all-optical Code Division Multiple Access (CDMA) system based on optical holography is disclosed. In this technique the energy of an incoming information light signal is spread over a spatial domain by a two-dimensional spatial encoder which includes a mask having regions of first and second transmission characteristics corresponding to the unique code assigned to a particular source. Subsequent decoding, which is accomplished by an optical matched filter through the use of a hologram, spatially despreads the energy of the information light signal and produces a focused light beam which serves as input to a code division detector.
    Type: Grant
    Filed: January 15, 1993
    Date of Patent: August 1, 1995
    Assignee: Bell Communications Research, Inc.
    Inventors: Eung G. Paek, Jawad A. Salehi
  • Patent number: 5426521
    Abstract: A method of and apparatus for efficiently correcting an aberration of an optical system used to record a hologram at the stage of reconstructing an image of the hologram. At the stage of reconstructing an image of a hologram (3), which contains the record of interference fringes formed by a reference plane wave and an object wave modulated by a sample, by applying a plane wave for reconstruction to the hologram (3) from a laser (1), an aberration of an optical system used to record the hologram (3) is canceled by the phase distribution on a liquid crystal panel (6) having a spatial phase modulation function, which is disposed on the Fourier transform plane, thereby correcting the aberration. The phase distribution on the liquid crystal panel (6) can be changed flexibly by a computer (9) in accordance with the aberration coefficients or degree of defocusing of the recording optical system.
    Type: Grant
    Filed: December 22, 1992
    Date of Patent: June 20, 1995
    Assignees: Research Development Corporation of Japan, Akira Tonomura
    Inventors: Jun Chen, Guanming Lai, Kazuo Ishizuka, Akira Tonomura
  • Patent number: 5406412
    Abstract: A high-resolution synthetic aperture, adaptive optics system includes an imaging system having a plurality of optical elements including at least a primary mirror which is a section of the aperture to be synthesized, and a detector for receiving the radiation collected by the primary mirror; and a device for rotating the primary mirror section through a number of angular positions about the aperture being synthesized to obtain a plurality of component images of an object, at least one from each of the positions; a device for sensing distortion of an incident wavefront; and a device responsive to distortions of the wavefront for locally adjusting at least one of the optical elements to correct distortions in the wavefront.
    Type: Grant
    Filed: August 6, 1993
    Date of Patent: April 11, 1995
    Assignee: Visidyne, Inc.
    Inventors: Theodore F. Zehnpfennig, Saul A. Rappaport
  • Patent number: 5383056
    Abstract: A Fourier transform lens assembly suited for use in an optical information processor includes a first lens group having a positive power, a second lens group having a negative power disposed on one side of the first lens group, and a third lens group having a positive power disposed on the side opposite to the first lens group with respect to the second lens group. The distance between a front focal plane and a back focal plane of the Fourier transform lens assembly is less than two times a focal length of the Fourier transform lens assembly.
    Type: Grant
    Filed: September 28, 1992
    Date of Patent: January 17, 1995
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Kanji Nishii, Masami Ito, Atsushi Fukui
  • Patent number: 5379150
    Abstract: A spatial frequency filter used in a pattern defect detection device, including a pattern which includes a black spot having a diameter expanded by a controlled amount in comparison with the diameter of a black spot on a photosensitive plate obtained by exposure by diffracted light from a pattern on a model specimen.
    Type: Grant
    Filed: December 30, 1993
    Date of Patent: January 3, 1995
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yoko Miyazaki, Toshimasa Tomoda, Hitoshi Tanaka, Nobuyuki Kosaka, Toyomi Ohshige
  • Patent number: 5337180
    Abstract: Spatially variable nonlinear optical thresholding in the Fourier plane reduces signal-dependent noise, such as scalar multiplicative noise. Coherent artifact noise reduction by a factor of four is attained using deamplifying photorefractive two-beam coupling. A variable light transmittance threshold across a spatially thresholded light modulating element such as a photorefractive crystal is utilized for this purpose.
    Type: Grant
    Filed: July 29, 1992
    Date of Patent: August 9, 1994
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Charles L. Woods, Jihad Khoury
  • Patent number: 5327287
    Abstract: A light intensifying device for use with cameras, telescopes, and other optical devices. The lightweight device can be easily manufactured and assembled from molded components of high durability plastic. When used as an attachment with cameras or telescopes the device will provide greater quantities of of light to allow for greater magnification and better image resolution for distant objects. The device will double the amount of light and can be used in conjunction with a camera focal length doubler which doubles the focal length but decreases the light by one half.
    Type: Grant
    Filed: March 22, 1993
    Date of Patent: July 5, 1994
    Inventor: Curtis L. Atchley
  • Patent number: 5327286
    Abstract: An optical correlation unit for correlating the images of an inspection object and a reference object. The unit uses two phase modulating reflective spatial light modulators. A first spatial light modulator receives electronic input in the form of image data representing the inspection object. It modulates incoming light with this input and reflects the modulated output to a first Fourier transform lens. This lens provides the optical input to a second spatial light modulator, whose electronic input is transform data representing the complex conjugate of the Fourier transform of the reference image. The electronic input modulates the optical input, resulting in the Fourier product of the two images, which is then transformed to provide correlation data.
    Type: Grant
    Filed: August 31, 1992
    Date of Patent: July 5, 1994
    Assignee: Texas Instruments Incorporated
    Inventors: Jeffrey B. Sampsell, Rachelle J. Bienstock
  • Patent number: 5317651
    Abstract: A signal processing device used for processing images including an optical correlator combined with a neuonal processor.
    Type: Grant
    Filed: May 10, 1993
    Date of Patent: May 31, 1994
    Assignee: Thomson-CSF
    Inventors: Philippe Refregier, Jean-Pierre Huignard
  • Patent number: 5311359
    Abstract: An optical correlator system having a plurality of reflective optical components, both active and passive, positioned (1) between a source of electromagnetic radiation, such as a visible beam of coherent light, and an output detector array, and (2) around an asymmetrical perimeter of a planar support body to develop an asymmetrically folded optical axis or path wholly within the body where the path is traversed by the beam SO THAT information processed by the active optical components along the optical path and imparted to the optical beam enable the optical detection of an unknown object at the detector array which is then subject to an identification process.
    Type: Grant
    Filed: December 24, 1992
    Date of Patent: May 10, 1994
    Assignee: Litton Systems, Inc.
    Inventors: John R. Lucas, Andrew M. Pollack, Stuart A. Mills
  • Patent number: 5307184
    Abstract: An exposure apparatus capable of making exposure for concentric circular periodic grating is provided with a quarter-wave plate (4), an ND filter (8a) having step-wisely different transmissions with boundaries of circle or a group of circles, an axially symmetric-shaped patterning mask (8b), an interference lens (9), before a sample substrate (10) having a photosensitive film (11). The interference lens (9) has a form of rotation symmetry with respect to optical axis (9L), and its incident surface (9P) is a flat plane, and its exit surface (9S) is a surface of revolution which is close to a circular cone.
    Type: Grant
    Filed: April 19, 1993
    Date of Patent: April 26, 1994
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Seiji Nishiwaki, Junichi Asada, Shinji Uchida
  • Patent number: 5300756
    Abstract: A method for severing integrated-circuit conductive links by laser power employs a phase plate (26) to shape the laser beam's intensity profile. The profile thus imparted to the beam approximates the Fourier transform of the intensity profile desired on the workpiece (34). As a consequence, when a focusing lens (32) receives a beam having the profile imparted by the phase plate (26), it focuses that beam into a spot on the workpiece (34) having an intensity profile more desirable than the ordinary Gaussian laser-beam profile.
    Type: Grant
    Filed: October 22, 1991
    Date of Patent: April 5, 1994
    Assignee: General Scanning, Inc.
    Inventor: James J. Cordingley
  • Patent number: 5289299
    Abstract: A technique for all-optical Code Division Multiple Access (CDMA) system based on optical holography is disclosed. In this technique the energy of an incoming information light signal is spread over a spatial domain by a two-dimensional spatial encoder which includes a mask having regions of first and second transmission characteristics corresponding to the unique code assigned to a particular source. Subsequent decoding, which is accomplished by an optical matched filter through the use of a hologram, spatially despreads the energy of the information light signal and produces a focused light beam which serves as input to a code division detector.
    Type: Grant
    Filed: January 15, 1993
    Date of Patent: February 22, 1994
    Assignee: Bell Communications Research, Inc.
    Inventors: Eung G. Paek, Jawad A. Salehi
  • Patent number: 5285438
    Abstract: A motionless parallel head reads an optical disk having an active surface encoded with an arrayed multiplicity of one-dimensional holograms. Each 1-D hologram is a computer-encoded representation of, typically, one 128 pixel slice of an image. A group, typically 128, 1-D holograms are positionally distributed, and positionally shifted or staggered one to the next, radially along the disk's active surface so as to fit a complete radius. Typically 14,000 groups are circumferentially-displaced around a 51/4" Compact Disk (CD), forming a herringbone pattern. During readout the encoded CD is simultaneously illuminated along the entirety of one of its radius lines within which a group of holographic data blocks are fitted.
    Type: Grant
    Filed: October 31, 1991
    Date of Patent: February 8, 1994
    Assignee: Regents of the University of California
    Inventors: Philippe J. Marchand, Ashok V. Krishnamoorthy, Pierre Ambs, Kristopher Urquhart, Sadik C. Esener, H. Sing Lee
  • Patent number: 5264912
    Abstract: An apparatus used to inspect patterned wafers and other substrates with periodic features for the presence of particles, defects and other aperiodic features in which a spatial filter placed in the Fourier plane is used in combination with either broadband illumination, angularly diverse illumination or both. In contrast to prior devices that direct light from a single monochromatic source through a pinhole aperture stop, embodiments are describes that illuminate a patterned substrate using (1) a single monochromatic source with a slit-shaped aperture stop for angularly diverse illumination, (2) a single broadband source with a pinhole aperture stop for broadband illumination, (3) a single broadband source with a slit-shaped aperture stop for both broadband and angularly diverse illumination, or (4) multiple sources with an aperture stop for each source for at least angularly diverse illumination.
    Type: Grant
    Filed: February 7, 1992
    Date of Patent: November 23, 1993
    Assignee: Tencor Instruments
    Inventors: John L. Vaught, Michael E. Fein, Armand P. Neukermans
  • Patent number: 5245619
    Abstract: Apparatus for transforming a conventional beam of coherent light, having a Gaussian energy distribution and relatively high divergence, into a beam in which the energy distribution approximates a single, non-zero-order Bessel function and which therefore has much lower divergence. The apparatus comprises a zone plate having transmitting and reflecting zones defined by the pattern of light interference produced by the combination of a beam of coherent light with a Gaussian energy distribution and one having such a Bessel distribution. The interference pattern between the two beams is a concentric array of multiple annuli, and is preferably recorded as a hologram. The hologram is then used to form the transmitting and reflecting zones by photo-etching portions of a reflecting layer deposited on a plate made of a transmitting material. A Bessel beam, containing approximately 50% of the energy of the incident beam, is produced by passing a Gaussian beam through such a Bessel zone plate.
    Type: Grant
    Filed: January 3, 1992
    Date of Patent: September 14, 1993
    Inventor: James W. Kronberg
  • Patent number: 5235461
    Abstract: An optical correlator system for encoding a complex optical image onto a erent beam of light such as a laser and comparing it with a reference complex image. One embodiment of the invention encodes phase only information of the complex image onto the coherent beam of light by means of a liquid crystal television receiver. The light beam is passed through the liquid crystal television receiver, whose pixels are manipulated to provide phase information concerning the image. A second embodiment of the invention encodes both phase and amplitude components of a complex image onto the coherent beam of light such as a laser beam. Either or both encodings are utilized in the optical correlator system.
    Type: Grant
    Filed: March 30, 1992
    Date of Patent: August 10, 1993
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: James C. Kirsch, Don A. Gregory
  • Patent number: 5235439
    Abstract: A pattern recognition apparatus and a method for operating same. The apparatus includes a volume holographic medium (4) having a plurality of Fourier-space volume holograms representing pattern templates stored within. The apparatus further includes a spatial light modulator (1) and a phase encoder (2). The phase encoder has an output optically coupled to the medium by a first Fourier transform lens (3). The spatial light modulator spatially modulates a spatially uniform laser beam (7) in accordance with an unknown pattern. The two-dimensional phase encoder causes the spatially modulated laser beam to be spatially distributed prior to application to the medium. The apparatus further includes a detector (6, 11) having an input optically coupled by a second Fourier transform lens (5) means to an angular spectrum of plane waves generated by the medium in response to the output of the spatial modulator, phase encoder, and first Fourier lens.
    Type: Grant
    Filed: December 20, 1991
    Date of Patent: August 10, 1993
    Assignee: Northrop Corporation
    Inventor: Harold M. Stoll
  • Patent number: 5233554
    Abstract: An optical correlation system employing the degenerate four wave mixing uses cross-polarized pump and probe beams to prevent the writing of a volume transmission phase hologram in a photorefractive crystal having an applied electric field parallel to the optic axis of the system, so that system response does not depend on the time required to write or erase such a transmission hologram.
    Type: Grant
    Filed: September 10, 1990
    Date of Patent: August 3, 1993
    Assignee: United Technologies Corporation
    Inventors: William F. Conley, John H. Mitchell
  • Patent number: 5216541
    Abstract: An optical associative identifier is disclosed which is used to determine the closest match between an image to be identified and a plurality of reference images. The identifier includes a display area for displaying the various images, the display area additionally functioning as a spatial light modulator. First and second optical Fourier transform devices are included which are used to compare the reference images to the image to be identified. The output light intensity of each of the reference images is modulated in accordance with a two-dimensional intensity distribution corresponding to the correlation between the image to be identified in each of the reference images. Based upon a comparison of these output light intensities, a match between the image to be identified and one of the reference images can be made.
    Type: Grant
    Filed: May 8, 1990
    Date of Patent: June 1, 1993
    Assignee: Sumitomo Cement Company Ltd.
    Inventors: Toshiharu Takesue, Yasuhiro Takemura
  • Patent number: 5216529
    Abstract: A technique for all-optical Code Division Multiple Access (CDMA) system based on optical holography is disclosed. In this technique the energy of an incoming information light signal is spread over a spatial domain by a two-dimensional spatial encoder which includes a mask having regions of first and second transmission characteristics corresponding to the unique code assigned to a particular source. Subsequent decoding, which is accomplished by an optical matched filter through the use of a hologram, spatially despreads the energy of the information light signal and produces a focused light beam which serves as input to a code division detector.
    Type: Grant
    Filed: January 15, 1992
    Date of Patent: June 1, 1993
    Assignee: Bell Communications Research, Inc.
    Inventors: Eung G. Paek, Jawad A. Salehi
  • Patent number: 5187598
    Abstract: A pulse train in the presence of random noise and other pulse trains is identified by controlling pixels in a raster display in accordance with incoming signals; using the raster display to modulate a laser beam with the pulses; Fourier-transforming the modulated beam, then performing a Cartesian to polar coordinate transformation on the Fourier-transformed beam; inverse Fourier transforming the coordinate-transformed beam, and passing the result through a line spatial filter and focusing the filtered beam on a one-dimensional detector array.
    Type: Grant
    Filed: August 26, 1991
    Date of Patent: February 16, 1993
    Assignee: United Technologies Corporation
    Inventors: Thomas J. Posluszny, Dennis W. Davis
  • Patent number: 5185815
    Abstract: A multiple target correlation system for unambiguously detecting, locating and determining the orientation of an array of multiple targets or objects. The multiple target correlator provides a means for fabricating a matched filter array or multiple matched filter with multiple targets stored on a single plate and a method for interrogating this multiple target matched filter with multiple scene images thereby providing for the identification of each object or target and determining its location and orientation in coordinates that are user selectable. The multiple target correlator utilizes a multiple matched filter having two matched filters for each particular object or target stored thereon, and each matched filter is positioned at a unique angle.
    Type: Grant
    Filed: November 4, 1991
    Date of Patent: February 9, 1993
    Assignee: Grumman Aerospace Corporation
    Inventor: Robert W. Brandstetter
  • Patent number: 5179455
    Abstract: A preferred embodiment of the optical reconstruction assembly 50 in which the assembly 50 includes an assembly housing 52 that is a unitary unit for supporting a spatial filter 72 and a light source 74 in a single plane at the optical length "L" from a collimating lens 86. A liquid container 88 is mounted to the assembly housing 52 containing the holographic liquid 90. The light source 74 and the spatial filter 72 are spaced a fixed distance "A" which is less than the optical diameter "D" of the collimating lens 86.
    Type: Grant
    Filed: November 22, 1991
    Date of Patent: January 12, 1993
    Assignee: Advanced Imaging Systems
    Inventor: George F. Garlick
  • Patent number: 5170289
    Abstract: An optical correlator console for mounting and assembling the components of an optical correlator system in a unique stable, compact and functional configuration in which all of the components are mounted in a compact configuration on upper and lower sides of a base support plate. The components which do not ordinarily require accessibility are mounted below the support plate and the components which ordinarily require accessibility during operation and use of the optical correlator are mounted above the support plate. The lower side of the support plate mounts a laser source and a collimator along with several other incidental optical components, with the laser source providing a laser beam as an input to the collimator which provides an expanded and collimated optical beam. The additional incidental optical elements can include a spatial filter and a shutter mounted interposed between the laser source and the collimator.
    Type: Grant
    Filed: February 1, 1991
    Date of Patent: December 8, 1992
    Assignee: Grumman Aerospace Corporation
    Inventors: Kenneth G. Leib, Edward V. Sullivan