Abstract: Systems and methods for providing a wider FOV for a telescope system are disclosed. In one embodiment, a telescope includes a primary mirror having an orifice, where an optical path originates from an object positioned in front of the primary mirror and reflects off the primary mirror. A secondary mirror is disposed adjacent to the primary mirror, where the optical path reflects off the secondary mirror and passes through the orifice in the primary mirror. The telescope includes a set of extended field corrector optics disposed along the optical path, the extended field corrector optics positioned to reflect light incident from the secondary mirror, where the set of extended field corrector optics comprises two corrector mirrors. A tertiary mirror is disposed along the optical path and adjacent to the extended field corrector optics, the tertiary mirror positioned to reflect the light incident from the extended field corrector optics.

Abstract: A method for manufacturing an imaging device is provided. The method comprises forming a contact pad over a semiconductor substrate. The contact pad has a malleable metal. The method further comprises providing a readout circuit having a first side and a contact plug. The contact plug has a base affixed to the first side of the readout circuit and a plurality of prongs extending from the base away from the first side. The first side of the readout circuit is moved towards the substrate so that the prongs of the contact plug are pressed into the pad and displace a portion of the pad into a space defined by and between a first and a second of the prongs. Stop elements formed over the substrate are aligned with and contact stop elements provided on the readout circuit so that the prongs are inhibited from passing completely through the contact pad.

Abstract: A bearing assembly suitable for use in a gimbal servo system is provided. The bearing assembly comprises a shaft having an end adapted to be coupled to a payload, a sleeve disposed over the shaft, an inner bearing rotatingly coupled to the shaft and the sleeve, an outer housing disposed over the sleeve, an outer bearing rotatingly coupled to the sleeve and the outer housing such that the sleeve is adapted to rotate about the shaft relative to the housing, a first motor operatively configured to rotate the shaft relative to the outer housing, and a second motor operatively configured to rotate the sleeve about the shaft. The second motor rotates the sleeve in a predetermined direction at a predetermined velocity such that a sum of the predetermined velocity and a velocity associated with inner bearing friction remains positive regardless of the direction of the shaft rotation.

Abstract: An image sensor is provided that includes a focal plane array; a cold shield having a top wall disposed over the focal plane array and defining an aperture operatively configured to be selectively switched between a first diameter and a second diameter that is larger than the first diameter; and a filter element disposed between the cold shield aperture and the focal plane array. The filter element includes a first band-pass filter and a second band-pass filter. The first band-pass filter is disposed directly beneath the cold shield aperture when the cold shield aperture is switched to the first diameter or the second diameter. The second band-pass filter is covered by the top wall of the cold shield when the cold shield aperture is switched to the first diameter and is disposed directly beneath the cold shield aperture when the cold shield aperture is switched to the second diameter.

Abstract: A pixel structure for use in an infrared imager is provided. The pixel structure includes a substrate and a bolometer. The bolometer includes a transducer that has a spaced apart relationship with respect to the substrate and has an electrical resistance that varies in response to changes in the temperature of the transducer. The bolometer also includes an absorber that has a spaced apart relationship with respect to the transducer and has a thermal connection to the transducer permitting radiation absorbed by the absorber to heat the transducer. The absorber has a top side defining a recess or channel in the absorber. The recess or channel is adapted to effect the propagation path of a portion of radiation received by the absorber such that the radiation portion is absorbed by the absorber rather than exiting the absorber. The recess or channel also decreases the thermal mass of the bolometer.

Abstract: An avalanche photodiode is operated in avalanche mode at a selected reverse bias that achieves high gain and a reduced gain normalized dark current.

Abstract: A photodiode for detection of preferably infrared radiation capable of detecting two different wavelengths wherein photons are absorbed in one region and detected in another. In one example embodiment, an absorbing P region is abutted with an N region of lower doping such that the depletion region is substantially (preferably completely) confined to the N region. The N region is also chosen with a larger bandgap than the P region, with compositional grading of a region of the N region near the P region. This compositional grading mitigates the potential barrier between the respective bandgaps. Under first voltage conditions a potential barrier prevents minority carriers from moving from the P region to the N region, but photons of energy large enough to generate minority carriers within the N region are detected. Under reverse bias, the barrier is substantially reduced or disappears, allowing charge carriers to move from the absorbing P region into the N region (and beyond) where they are detected.

Abstract: An infrared radiation (“IR”) focal plane array (“FPA”) imager includes a detector array chip containing pixels having substantially one-hundred percent operability. Each of the pixels contains a plurality of interdigitated sub-detectors, where the sub-detectors are selectively operable to provide for collection of photogenerated minority charges representative of all or substantially all of the IR radiation absorbed by the detector array chip of the FPA imager.

Abstract: A high-performance image-forming optical objective lens made compact and thin, particularly in the object side direction, by twice folding the optical path by means of two prism lenses longitudinally separated and arranged in an angular relationship to one another. The prisms have entrance and exit faces each of which is constructed of a curved surface having optical power, as well as having a rotationally symmetric polynomial aspheric attribute. The image-forming optical objective is particularly suited to helmet-mounted applications wherein the angular means for folding the optical path provides for an optical objective configuration that closely conforms to the exterior surface contour of the helmet, while providing a minimal forward projection in object space from the helmet.

Abstract: A photodiode for detection of preferably infrared radiation wherein photons are absorbed in one region and detected in another. In one example embodiment, an absorbing P region is abutted with an N region of lower doping such that the depletion region is substantially (preferably completely) confined to the N region. The N region is also chosen with a larger bandgap than the P region, with compositional grading of a region of the N region near the P region. This compositional grading mitigates the barrier between the respective bandgaps. Under reverse bias, the barrier is substantially reduced or disappears, allowing charge carriers to move from the absorbing P region into the N region (and beyond) where they are detected. The N region bandgap is chosen to be large enough that the dark current is limited by thermal generation from the field-free p-type absorbing volume, and also large enough to eliminate tunnel currents in the wide gap region of the diode.

Abstract: A photodiode for detection of preferably very long wavelength infrared radiation wherein low energy photons are absorbed in one region and detected in another. In one example embodiment, an absorbing P region is abutted with an N region of lower doping such that the depletion region is substantially (preferably completely) confined to the N region. The N region is also chosen with a larger bandgap than the P region, with compositional grading of a region of the N region near the P region. This compositional grading mitigates the barrier between the respective bandgaps. Under reverse bias, the barrier is substantially reduced or disappears, allowing charge carriers to move from the absorbing P region into the N region (and beyond) where they are detected. The N region bandgap is chosen to be large enough that the dark current is limited by thermal generation from the field-free p-type absorbing volume, and also large enough to eliminate tunnel currents in the wide bandgap region of the diode.

Abstract: An infrared radiation (“IR”) focal plane array (“FPA”) imager includes a detector array chip containing pixels having substantially one-hundred percent operability. Each of the pixels contains a plurality of interdigitated sub-detectors, where the sub-detectors are selectively operable to provide for collection of photogenerated minority charges representative of all or substantially all of the IR radiation absorbed by the detector array chip of the FPA imager.

Abstract: Electromagnetic energy is detected with high efficiency in the spectral range having wavelengths of about 1–2 microns by coupling an absorber layer having high quantum efficiency in the spectral range having wavelengths of about 1–2 microns to an intrinsic semiconducting blocking region of an impurity band semiconducting device included in a solid state photon detector.

Abstract: A hyperspectral scene generator generates a projected linear scene where the spectral characteristics at each location that forms the scene are dynamically and arbitrarily controllable. The generator can be controlled to generate a projected linear scene including a targeted object and arbitrary spectral content that duplicates the spectral content of real targets and backgrounds to facilitate testing of target identification software of a hyperspectral imaging system in view of expected actual field operation of the sensor of the imaging system.

Abstract: A precision mirror displacement assembly for controlling rotation of a mirror about a rotational axis to obtain a precise mirror orientation includes a mirror having an enhanced backside and a reflective front surface. The enhanced backside has a sufficient thickness to provide that attachment of mirror displacement control components, such as portions of actuator and position sensor assemblies, to the backside during manufacture of the mirror assembly does not cause distortion of the reflective front surface of the mirror. The enhanced backside also is of sufficient thickness to avoid distortion of the front surface based on interaction of the mirror with mechanical stops and actuator components that are attached to a base of a separate housing of the mirror assembly that opposes the backside of the mirror.

Abstract: A gray code is produced from a minimum of gate logic by making available and monitoring master outputs of master-slave latch pairs, where the latch pairs are arranged to form a cascading chain of toggle flip-flop stages. The least significant bit through one less than the most significant bit in the gray code is supplied by the master latch outputs and the most significant gray code bit is supplied by the slave latch output of the last toggle stage in the chain.

Abstract: A pixel structure, which forms one element of a focal plane array, includes a bolometer having a detector and an insulator. The detector that is made from a material that absorbs incident thermal radiation and has an electrical resistance that varies in response to changes in the temperature of the material. The insulator has a plurality of serpentine legs disposed completely underneath the detector so that the insulator extends between the detector and the substrate. And the insulator supports the detector in a spaced-apart relationship with respect to the substrate to thermally isolate the detector from the substrate. To further improve the performance of the bolometer, the bolometer includes a resonant layer between the detector and the insulator. The resonant layer is disposed such that areas defined between the detector and the resonant layer, and between the resonant layer and the insulator, form first and second resonant cavities, respectively.

Abstract: The present invention provides a sealed-cavity miscrostructure and an associated method for manufacturing the microstructure. Specifically, the microstructure of the present invention includes first and second wafers that are positioned relative to one another so as to form a cavity between the wafers. The microstructure further includes a seal between the first and second wafers and surrounding the cavity to create a pressure seal for the cavity. This seal allows the cavity of the microstructure to be maintained at a predetermined pressure different from that of the atmosphere outside the cavity. Importantly, the microstructure of the present invention further includes a structrual bond between the first and second wafers that structurally intergrates the first and second wafers. The structural bond renders the microstructure more rugged such that the microstructure can withstand expansion, vibrational, and shock stresses experienced by the microstructure during subsequent manufacturing and use.

Abstract: A reference bolometer and the associated methods for fabricating a reference bolometer and for fabricating an array of bolometers are provided. The reference bolometer is fabricated such that a thermally conductive layer underlies the detector element, i.e., the absorber and transducer elements, and is encapsulated by a protective coating. The protective coating serves to prevent the thermally conductive layer underlying the detector element of the reference bolometer from being etched during the process of etching or otherwise removing other portions of the thermally conductive layer that underlie the detector elements of the imaging bolometers. As such, the thermally conductive layer of the reference bolometer maintains the desired thermal communication between the detector element and the substrate such that the output of the reference bolometer is unaffected by incident radiation.

Abstract: An optical filter system is described wherein a fluid, such as gaseous phases of water or carbon dioxide, is frozen onto a transmissive substrate positioned in the optical path of an infrared sensor system. The frozen material, which is preferably maintained at cryogenic temperatures, acts as a natural optical filter, absorbing certain undesirable wavelength bands of atmospheric infrared radiation, thus preventing them from reaching the detector of the sensor system. Simultaneously, the optical filter system allows certain desirable wavelength bands of infrared radiation to be transmitted, thus permitting them to reach the detector of the sensor system. The overall effect is to reduce the amount of noise and clutter generated by the undesirable atmospheric infrared radiation from reaching the detector of the sensor system, thus increasing the resolution and effectiveness of the sensor system.