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: An objective lens assembly suitable for use in helmet-mounted applications. The objective lens assembly comprises two prisms that collectively are configured, oriented and bonded relative to each other to separate and allow simultaneous imaging of two separate spectral bands (such as VNIR and LWIR bands) received from the same object scene via a common window such that the object scene may be viewed from the same perspective without the effects of parallax.

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: A vibration isolator system for attaching a payload to a supporting base is provided, the payload having a center of mass and the system consisting of at least three vibration isolating pods. Each pod has two associated, non-parallel, elastic struts. A first end of each strut is attached to the supporting base and a second end of each strut is attached to the payload at a respective mounting point, and the a projected elastic center of the system is substantially co-located with said center of mass. The vibration isoloator system is operable to substantially prevent translational vibration of the supporting base from inducing angular rotation of the payload.

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 bearing assembly suitable for use in a gimbal servo system is provided. The bearing assembly comprises a housing, a first shaft, a bearing rotatingly coupling the first shaft to the housing such that the first shaft is adapted to rotate about an axis relative to the housing, a second shaft having a first end adapted to be coupled to a payload, and a flex pivot element pivotally coupling an end of the first shaft to a second end of the second shaft such that the second shaft is adapted to rotate relative to the first shaft via the flex pivot element. In response to a rotation of the second shaft, the flex pivot element is adapted to pivot an angle about the first shaft axis. The pivot angle reflects a displacement of the second shaft relative to the first shaft and corresponds to a friction disturbance of the bearing.

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: A tunable infrared detector is provided that includes a substrate, a bottom wavelength detector formed over the substrate, a top wavelength detector formed over the first wavelength detector layer, and an interferometer filter formed over the top wavelength detector layer and the bottom wavelength detector layer. The interferometer filter is operatively configured to pass a first wavelength associated with a first portion of a predetermined band and a second wavelength associated with a second portion of the predetermined band to the top wavelength detector. The top wavelength detector is operatively configured to detect each wavelength associated with the first portion of the predetermined band and to transmit each wavelength associated with the second portion of the predetermined band to the bottom wavelength detector. The bottom wavelength detector is operatively configured to detect each wavelength associated with the second portion of the predetermined band.

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: 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.