The Boeing Company

The Singer Company

Rockwell International Corporation

US Government as Represented by the Secretary of the Army

United States of America as Represented by the Secretary of the Air Force

Richard H Burns

Michael R Smith

Kenneth Crabtree

Sandor Holly

Nicholas Koumvakalis

Steven Edward Muenter

Kenneth Charles Widen

Donald Elliot Harrington

Irving J Bell

Bernard P Hildebrand

William M Hall

A method and apparatus for detecting objects. A first plurality of electromagnetic signals having a first frequency and a second plurality of electromagnetic signals having a second frequency are transmitted. At least one of the first frequency and the second frequency is changed through a range of frequencies. A delayed difference frequency signal substantially equal to a difference between the first frequency and the second frequency is monitored for. The delayed difference frequency signal is generated by an object having non-linear electrical characteristics in response to the object receiving the first plurality of electromagnetic signals and the second plurality of electromagnetic signals. A range measurement is generated for the object by comparing the delayed difference frequency signal and an undelayed difference frequency signal. The undelayed difference frequency signal is substantially equal to the difference between the first frequency and the second frequency.

Difference frequency detection with range measurement

A composite dipole array assembly can have a composite dipole array defined by a plurality of antenna elements and a plurality of non-linear element electrically interconnecting pair of the antenna elements. A reflector can be configured to reflect electromagnetic energy toward the antenna elements. A lens can be configured to focus electromagnetic energy upon the antenna elements. In this manner, the efficiency of the composite dipole array is enhanced.

Composite dipole array assembly

A method and apparatus for a focal plane array with serial, variable bit width analog to digital converter. The focal plane array includes a plurality of pixels and a dynamically reconfigurable analog to digital converter. The controller determines a number of digital output bits required to generate digital output at a selected conversion resolution. A sample and hold circuit holds an analog voltage from a pixel to form a captured analog signal. A one-bit converter stage processes an instance of a captured analog signal to generate an output bit. The controller iteratively processes a residue voltage through the one-bit converter stage a number of times required to generate the number of digital output bits to form a digital output with the user defined conversion resolution.

Focal plane array with serial, variable bit width analog to digital converter

A synthetic aperture radar (SAR) system includes a transmitter capable of transmitting a pair of signals that each have a predetermined frequency in the optical band of the electromagnetic spectrum. The predetermined frequency can be selected, for example, to provide a level of resistance to at least one of movement of the target, target vibration and optical path length variations, and can further be selected based upon a predefined range and azimuth resolution. The SAR system also includes a receiver capable of receiving at least a portion of the pair of signals that has been reflected off of a target. In this regard, the receiver is capable of processing the reflected portion of the pair of signals based upon a difference frequency between the transmitted pair of signals.

System and method for increasing resistance to target vibrations in synthetic aperture radar signals

Aligning a stable ring resonator by the use of an inversion mechanism ins the resonator and a pair of anti-symmetric masks. Each mask has opaque and clear parts and the masks are anti-symmetric in that, in use, one mask is positioned so that its opaque and clear parts are anti-symmetric to the opaque and clear parts of the other mask when it is in position. One mask is placed between the radiation source and the beam splitter while the other mask is placed between the beam splitter and the focal plane on which the two beam portions created by the beam splitter focus. One beam portion is directly reflected from the beam splitter and the other portion is transmitted into the resonator and is inverted while following a beam path within the resonator before being outcoupled through the beam splitter in a much weakened state. Thusly positioned, the anti-symmetric masks have the effect to attenuating the intensity of the reflected beam portion, so that the relative intensities of the transmitted and the reflected beam portions are more equal when they arrive at the focal plane. This, in turn, makes the alignment of the two focal spots easy. When the two spots merge completely the ring resonator is aligned.

Apparatus and method for aligning ring resonator

A method and apparatus for testing an optical system 64 having an optical axis and a desired optical wavefront. A hologram is formed containing a recording of the desired optical wavefront. The hologram is located on the optical axis. When the hologram 50 is played back, the desired optical wavefront 62 is produced and directed toward the optical system 64. Wavefront 62 is retroreflected from the optical system 64 containing any of the system's aberrations. The retroreflected wavefront 66 is then passed through the hologram. A reference wavefront 60 is produced which is substantially conjugate to the desired optical wavefront. The reference wavefront 60 interferes with the retroreflected desired optical wavefront 66 thereby producing an interference fringe pattern characterizing the optical system under test.

Holographic interferometer

An apparatus for varying the vergence of a beam of light from a laser including first and second focusing reflector means; one for receiving the beam of light and another for directing it away from the apparatus in a predetermined direction. Intermediate the two focusing reflecting means, there is provided an arrangement of substantially flat surface reflector means, one of which is moveable for varying the length of the path of the beam of light through the apparatus. In accordance with a preferred embodiment, the two focusing reflecting means comprise parabolic mirrors and the moveable reflector means comprises a piston mirror.

Coherent light vergence varying apparatus

A projection screen is formed as at least one reflective holograms each of which, when referenced with a projector, reconstructs a defined observation pupil.

Holographic projection screen

Graphic data entry in an interactive graphic display system is achieved by means of an apparatus that provides automatic centering of a pointing laser beam on a hand held cursor. The graphic display system provides a means for displaying and comparing through superposition full size overlaid graphical data and projected graphical data on a common display screen. It includes a steerable pointing laser the beam of which scans the display screen in response to a laser beam deflection circuit. The system also includes laser beam position sensing and indicating circuits which accurately measure the laser beam position. Centering of the laser beam on the cursor at the display screen is accomplished by dithering the beam uniformly about its average position in a discrete dither pattern and utilizing the dither pattern to determine misalignment of the beam's average position with respect to the center of the cursor. The cursor includes photo detector elements that are geometrically configured to conform to the dither pattern so that signals derived from an eccentric relationship of the beam dither pattern and the photo detector element configuration can be processed to provide beam misalignment direction and magnitude error signals. These error signals drive a servo system that centers the average beam position on the cursor. The function of the cursor is to manually or automatically measure the coordinator of graphical features on the display screen.

Cursor apparatus for interactive graphic display system

A system for sensing the position of a laser writing beam is provided wherein at least two laser beams of unlike frequency are superimposed on the laser writing beam. The combined laser beams are simultaneously deflected in a common optical deflection system. Once deflected, the unlike frequency laser beams are separated from the writing laser beam and focused onto a diffraction grating. The position of the focused beams of unlike frequency on the diffraction grating corresponds to the position of the writing laser beam on the writing media. The focused laser beams of unlike frequency produce a traveling interference pattern on the grating and are diffracted by the grating into a plurality of beams. By sensing the frequency of at least one of the beams diffracted by the grating, the position and movement of the writing laser beam can be determined.

Method and apparatus for sensing the position of a writing laser beam

A flat PLZT plate is utilized to form erasable images thereon which images may be projected or viewed directly. One embodiment includes electrically conductive islands on one side of the PLZT plate which are surrounded by and electrically isolated from an electrically conductive grid pattern. The portion of the PLZT plate located between an island and the surrounding portion of the grid pattern constitutes a pixel or image forming element. By grounding the grid pattern and applying an electrical charge to selected ones of the islands, an image can be formed on the PLZT plate which can be viewed directly or projected by means of polarized light. In order to form the erasable images on the PLZT plate by optical means, the grid pattern and islands are coated with a layer of photoconductive material upon which a layer of a transparent conductor is coated. By applying a potential to the transparent conductor and exposing the coated PLZT plate to an optical image, those islands subjected to the light radiation receive an electrical charge thereby forming a birefringence image in the PLZT plate.

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North Hollywood, CA, United States of America

Richard H Burns