Abstract: An imaging sensor for scanning a thermal image is disclosed. The imaging sensor comprises a first set of elemental detectors operable to receive a thermal image during a first portion of the calibration cycle. A second set of elemental detector is provided which are operable to receive the image during a second portion of the calibration cycle. Means are provided for calibrating the first and second sets of elemental detectors by comparing the output of the first set of elemental detectors during the first portion of the calibration cycle with the outputs of the second set of elemental detectors during the second portion of the calibration cycle.

Abstract: An imaging sensor for scanning an image in an object space is disclosed. The imaging sensor comprises a first and second plurality of infrared detectors. Also provided is a reflecting means for reflecting a predetermined portion of the object space on the first plurality of infrared detectors during first portion of the scanning cycle. The reflecting means is further able to reflect the predetermined portion of the object space on the second plurality of infrared detectors during the second portion of the scanning cycle. In a further embodiment, the orientation of the detectors permits each of the detectors to be calibrated with respect to another of the detectors by a sequential comparison of the outputs of pairs of the detectors whose fields-of-view overlap.

Abstract: A multibeam antenna system in which an antenna aperture element is deliberately selected to produce a divergent beam at a desired angular beamwidth. The antenna aperture may, for example, take the form of a hyperboloid reflector, a diverging lens, or a defocused paraboloid reflector. For the divergent secondary beams produced in these configurations, the angular beamwidth may be conveniently controlled by varying the mangification of the aperture or the degree of defocusing, without significantly affecting the gain or efficiency of the system. The degree of beam overlap may be independently controlled by scaling the size of the aperture, without significantly affecting the beamwidth, the gain or the efficiency.

Abstract: A method and improved apparatus for aligning a diffraction grating, as, for example, one used in tuning the output of a laser. The total angular misalignment .epsilon. between the incident and diffracted beams is a function of three angles: the tuning angle .theta.16, the angle of tilt .beta. between the plane of the grating 15 and the tuning rotational axis, and the angle .alpha. between the grating lines and the projection of the turning rotational axis in the plane of the grating 15. The present invention provides a method of aligning the diffraction grating so that the residual alignment error is very small over the desired range of tuning angle .theta. 16, by adjusting only .alpha. or only .beta. to zero at two reference tuning angles .theta..sub.0 and .theta..sub.1. Knowledge of the value of either .alpha. or .beta. is not necessary. For a CO.sub.2 laser tuned over the wavelength range 9.11 to 10.88 .mu.

Abstract: A method and apparatus are disclosed for providing a laser beam that is automatically aligned with a substantially rigid, stabilized platform or frame that can be oriented over a wide angular range, such as by the gimbals of a laser pointing and tracking system. A single-transverse-mode master laser oscillator 12 is mounted on the stabilized platform 13 which is part of the inner gimbal, which can be rotated about an elevation axis 16, and a multipass laser amplifier 21 wiht a phase conjugation mirror 22 and an optional nonlinear frequency-conversion device 20 are located off the inner gimbal. An outer gimbal or pedestal mount permits rotation about an azimuthal axis 17. The laser oscillator 12 and laser amplifier 21 are coupled by means of a beamsplitter 15 and two reflecting elements 18 and 19. The laser media used for the oscillator 12 and amplifier 21 are either the same, or compatible media having the same wavelength.

Abstract: An improved laser rangefinder and thermal imager with enhanced scanning mirror control is disclosed. Optical axes (11,12) are aligned parallel to each other. The system includes only one common thermal image/laser reception channel (8,9,10,11). The angular movement of scanning mirror 8 is compensated during the range finding operation. Synchronizing means (1,2,3,4) located in the beam path controls the movement of the scanning mirror. An improved method for controlling the movement of the scanning mirror which enhances the measuring range of the device is also disclosed. In order to receive CO.sub.2 radiation of narrow bandwidth which is reflected from a target, the cyclical movement of the scanning mirror (8) is precisely controlled in order to position it favorably during the range measuring operation. The frequency of the scanning function is retarded so that the scanning mirror (8) is moved only through a fraction of the width of the image field.

Abstract: The invention concerns an optical detection matrix (9) contained within a cryogenic chamber (3). Electrical image signals produced by the matrix (9) are converted into optical signals and transmitted out of the chamber (3) on lines 42A-42T. The optical signals on lines 42A-42T are converted into electrical signals carried on line 56.

Abstract: Apparatus is disclosed for the strain-free mounting of a component, such as a mirror 11, to a base in a manner that allows for differential thermal expansion or contraction to take place between the component and the base without distortion of the component. The mounting apparatus of the invention makes use of a linear bearing 10 that is rigid in all directions except one. Such a linear bearing is used at two or more points of support on the circumference of a mounting circle A. Relative motion in the linear bearings occurs along a line r which is an extension of a radius of the mounting circle. The linear bearings each contain two sets of opposed rolamite mechanisms 20a, 20b, 30a, 30b moving in parallel directions in the perpe=ndicular arms of a "Y"-shaped frame 18.

Abstract: A four mirror afocal optical system is disclosed. The primary mirror (12), secondary mirror (14), tertiary mirror (16), and quaternary mirror (18) form an afocal reimaging optical system which is off axis in both aperture and field angle. The secondary, tertiary and quaternary mirrors are tilted and decentered relative to the optical axis of the primary mirror to enhance image quality and to provide access to a real exit pupil.

Abstract: An afocal zoom lens system is provided that has particular utility for use in aircraft navigation systems where a unitary (1.0.times.) magnification power is desirable. Two embodiments are disclosed, the first providing an 8:1 magnification ratio with the second embodiment providing a 12:1 ratio. Both embodiments employ four lens groups including a front fixed objective lens (A,E), a second lens group including a negative zooming element (B,F), a third fixed group (C,G) and a fourth rear negative zooming element (D,H). In the highest magnification position, the lenses are arranged so that the front zooming element is positioned adjacent the positive lens of the the third group to form a weak negative doublet. In the minimum magnification position, the front zoom element is widely separated from the third group to create an inverse telephoto Galilean form.

Abstract: A method and apparatus are disclosed for providing a self-aligning phase conjugate laser beam that is automatically boresighted with an active or passive tracking sensor. A single-transverse-mode laser oscillator 12 and a tracking sensor 14 are mounted on opposite sides of an output coupling beamsplitter 15, all attached to a stabilized platform 13 which is part of the inner gimbal of a pointing and tracking system. A multipass laser amplifier 21 with a phase conjugation mirror 22 and an optional nonlinear frequency-conversion device 20 are located off the inner gimbal. The inner gimbal allows rotation of the stabilized platform about an elevation axis 16, and an outer gimbal or pedestal mount permits rotation about an azimuthal axis 17.

Abstract: A demand auto focus system is driven by scene information only, In a scanned video system as the camera is brought into focus the high frequency content of the video signal will increase. The video signal is passed through a band-pass filter and then rectified in a conditional integrator to generate a control signal whose amplitude indicates to the degree of focus. The control signal is stored and later compared to a control signal derived from a subsequent scanning. Once a significant change in control signal levels is deteced a drive signal is sent to the focusing device. If after being driven the subsequent scene has less high frequency content, then a drive signal in the opposite polarity or direction is sent to the focusing device. In this manner the scene is toggled toward optimum focus.

Abstract: An amplifier circuit 12 for an infrared detector 10 in a detector array formed on a large-scale integrated structure. The amplifier circuit is fabricated along with the detector on the structure and includes an amplifier stage capacitively coupled 14 to the detector 10 and an output stage. A switching FET 16 is provided to selectively couple the detector to an external biasing source and another switching FET 24 is provided to reset the amplifier stage after an integration period. In one embodiment the output stage 28 includes a storage capacitor 30 selectively coupled to the amplifier stage by a switching FET 32. In another embodiment the output encoding stage 28 includes a two-gate FET 32 to control the voltage on a storage capacitor 30. The two-gate FET controls a voltage source which periodically pulses and drains the capacitor. One FET gate is connected to the amplifier stage output and the other is connected to a clocking signal.

Abstract: An integrated optic holographic spectrometer (10) for analyzing electromagnetic radiation from a source (12) is disclosed. The holographic spectrometer (10) comprises a substrate (18) having aperture (20) for restricting the receipt of electromagnetic radiation. The spectrometer (10) also includes two optical waveguides (22, 24) for dividing the electromagnetic radiation received through the aperture (20) into at least a first and second portions. A geodesic lens (26) is provided for collimating the first and second portions of the electromagnetic radiation. Finally, the spectrometer (10) includes a linear detector array (28) optically communicating with the geodesic lens (26) to provide an output responsive to the interference between the first and second portions of the electromagnetic radiation received through the aperture (20).

Abstract: A method and apparatus for multiplexing signals from electromagnetic radiation detectors is disclosed. The apparatus (10) includes a plurality of elemental detectors (16-32) each of which is being operable to generate an output in response to receipt of electromagnetic radiation. Also provided is a circuit for frequency division multiplexing the output of said elemental detectors.

Abstract: A tool (10) is used for detecting whether material (14) on a reference surface (12) has exceeded a predetermined height. The tool (10) includes a housing (32) having a bottom surface with at least one opening (34) therein for receiving the material (14) whose height is to be tested. A probe means (44) is slideably mounted within the housing (32) and has one end located in the opening (34) for contacting the material (14). A circuit (18, 22) includes a pair of contacts (30) spaced a given distance from a predetermined portion of the probe (44). An indicator (66) is coupled to the circuit for signaling that the height of the material (14) exceeds the predetermined height when the probe (44) slide a sufficient distance so that the portion thereof closes the contacts (30).

Abstract: A piezoelectric fan is comprised of two counter-oscillating flexible blades that are driven at resonance by a bimorph comprised of two piezoceramic bending elements. The fan is provided within the flow duct of a circulating gas laser. The operation of the piezoelectric fan serves to create a flow of a laser gas medium in a desired direction through the flow duct, thereby replenishing the gas medium between a pair of laser electrodes. The fan has no wearing elements, such as bearings, and requires no bearing lubricant resulting in the elimination of lubricant hydrocarbon and bearing particulate contamination of the laser gas medium.

Abstract: A method and apparatus are disclosed for mounting an interferometer cavity such as a laser so that constant interferometer resonant frequency is maintained in spite of environmental vibration and other external acceleration forces. The invention can be used alone or in combination with prior art frequency stabilization systems, such as shock mounts and active feedback type stabilization systems.

Abstract: A new technique, and output encoding circuits using that technique, are disclosed for interfacing between a semiconductor IR detector 23 and associated output electronics 24, 25, 26, which technique and circuits transfer a charge packet onto a sense capacitor 22 that previously stored a reset level signal. The resulting stepped signal change, or delta, in the voltage present on that capacitor 22 is employed as the output signal.

Abstract: A method and apparatus are disclosed for testing for stuck- open faults in integrated circuits (10) having a plurality of combinational logic devices (18, 20). The apparatus includes a chain of shift register stages (22), with each stage including at least two latches (L1 and L3). The bits of an initialization test are shifted down the shift register and loaded into one of the latches (L3), while the bits of a detection test pattern are subsequently shifted down the chain and stored in the other latch (L1). A multiplexer (50) is provided for selecting one of the outputs from the two latches (L1, L3) so that the initialization test pattern and then the detection test pattern can be quickly applied to the combinational logic so as to minimize hazards which could invalidate the test results.