Lockheed Martin Corporation

Ltv Aerospace & Defense Company

Other

Westinghouse Electric Corporation

Loral Vought Systems Corporation

Ltv Aerospace and Defense

William E Case

Dayton D Eden

Thomas R Schimert

Mark E Koch

Richard C McKee

Leslie L Thompson

An infrared radiation detector device has an array of detectors each of which comprises a pattern of parallel detector elements. Each detector produces a pixel signal for an image. The elements of the detector are photoconductive or photovoltaic bandgap materials, and the elements are spaced apart at a dimension which is equal to or less than the wavelength of the radiation to be received. Additional layered structures above and/or below the detector elements provide impedance matching between free space radiation and the radiation impedance of the detector elements to increase the capture of radiation.

Bandgap radiation detector

An infrared radiation detector device has an array of detectors each of which comprises a pattern of parallel detector elements. Each detector produces a pixel signal for an image. The elements of the detector are photoconductive or photovoltaic bandgap materials and the elements are spaced apart at a dimension which is equal to or less than the wavelength of the radiation to be received. Additional layered structures above and/or below the detector elements provide impedance matching between free space radiation and the radiation impedance of the detector elements to increase the capture of radiation.

A new system for millimeter wave electronic imaging is described. This system utilizes a spatial light modulator in the focal plane of the collection optics. Each pixel of the modulator is driven by a specific high duty cycle modulation function provided by a modulation function generation circuit. Thus the throughput radiation at each pixel is uniquely labeled(encoded). A post modulation detector sums the signal from all the pixels. Subsequent to detection, the appropriate transform of the sum signal yields specific pixel throughput radiation intensity levels. Several configurations are described including one transmittance configuration and two reflectance configurations. Three specific millimeter wave transmittance embodiments and one reflectance embodiment are also described.

Electronic imaging by encoded image detection

An infrared detector, having improved infrared absorptance and operating performance at or near ambient as well as the cryogenic temperature ranges. The infrared detector, in one embodiment includes a multi-filament HgCdTe detector region mounted upon a CdTe substrate, a metallic reflective region placed in front of, or behind, the HgCdTe detection region forming a resonant layer between the reflective region and HgCdTe. Electrical contacts operable to detect the change in resistance of the HgCdTe detector filaments are connected to the detector region. Embodiment for a back surface illuminated detector device is described for use in the 8 micron to 12 micron, longwave infrared (LWIR) range. Improved operation in the LWIR range at higher temperatures results in detector arrays having decreased cooling needs and infrared detector systems produced with a significant decrease in overall system weight.

Back surface illuminated infrared detector

Devices and methods are taught by this invention of populating excited energy levels with fundamental particles. When these populated excited energy levels are further pumped, a population inversion used in quantum electronic applications can result. Each of the various methods involve pumping on an excited energy level of an elemental physical system to cause, by the absorption of energy, the transition of fundamental particles from the excited energy level to a higher energy level. Part of the energy is used for transition of fundamental particles residing in neighboring elemental physical systems from the lowest energy to the excited energy level.

Population inversion by excited energy level absorption

In an optical radar system a coherent signal is transmitted at a variable position and the return signal, that is, the reflected portion of the coherent signal is received and coherently detected. The transmitter utilizes a scanning laser having an electron beam that impinges upon a variable reflectance mirror that terminates one end of an optical cavity. An oscillating mode is generated within the resonant cavity when the electron beam locally heats the surface of the variable reflectance mirror to create a pixel that reflects light in a diffracted pattern. The receiver utilizes a stable single mode laser to illuminate a variable reflectance surface. A receiver electron beam generates a plurality of receiver pixels at various positions. The diffracted light from each pixel generates a plurality of variable angle local oscillator beams that are summed with the return signal at a beamsplitter. The output of the beamsplitter is applied to the surface of a detector array. One of the local oscillator beams is positioned such that the return signal and the local oscillator beam overlap at one of the detectors in the array to provide coherent detection. The frequency of the first coherent signal and the second coherent signal are sampled by a first and second partially reflecting mirror. A frequency detector detects the output of the first and second partially reflecting mirror to detect the frequency difference between the first and second coherent signal and generate a control signal that adjusts the frequency of the first coherent signal. For heterodyne operation a selected frequency difference is generated whereas for homodyne detection a zero frequency difference is generated. An electronic computer coordinates the position of the scanning laser of the transmitter and the position of the local oscillator beams of the receiver such that one of the local oscillator beams will overlap with each of the corresponding return signals at the detector array. A second electronic computer processes the output of the detector array to provide information about the return signal.

Scanning laser for a scanning laser radar

Stimulated emission at the approximate wave length of 4.5 microns, 2.25 microns and 1.6 microns is obtained from pumping on an excited energy level. The phenomenon of photon avalanching is utilized to create a population inversion within three lower level states that have a substantially equal energy spacing to provide resonance between neighboring ions. This resonance feeds the photon avalanching process when pump having sufficient power in excess of the critical pump power irradiates a LaCl.sub.3 :Pr.sup.+3 crystal at an excited energy level to maintain a population inversion in an optical cavity.

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Arlington, TX, United States of America

William E Case