Abstract: A disclosed apparatus and method verify whether a hot spot within a scene is a valid laser-com signal, and further identify laser-com signals of interest. An extended Kalman filter (EKF) is applied to a received signal or beacon to detect whether it is modulated according to a square wave or other expected amplitude modulation pattern. Embodiments further determine whether the modulation frequency matches a signal or beacon of interest. In embodiments, a plurality of indexed EKF's are “tuned” to different modulation frequencies, and are used to identify a beacon's modulation frequency index. Where each EKF is required to compute amplitude and phase partial derivatives of the observation vector, the amplitude partials can be calculated according to the expected modulation pattern, and the phase partials can be calculated using a truncated Fourier or step-wise approximation of the expected modulation pattern. Embodiments further assume a time-invariant covariance matrix.

Abstract: A disclosed apparatus and method detect light source “hotspots” and recognize laser communication signals within a scene, while minimizing repeat consideration of previously detected light sources. Local maxima are identified in pixel frames from a focal plane array (FPA), and compared with a table of previous detections. FPA frames can be used directly for hotspot detection, or successive FPA frames can be subtracted for edge detection. Most recent detection frame numbers, coordinates, signal values, and/or other information can be updated in the table upon repeat detection of a hotspot. Source identifying information can be included in the table for entries that are identified as laser communication signals. Source identifying features can be evaluated so that only signals of interest are saved in the table. Hotspots that remain undetected after a designated number of frames can be deleted from the table.

Abstract: An apparatus and method for tracking a laser communication signal of interest incident on a focal plane array (FPA) identifies a plurality of “hotspots” in a scene of interest, and aligns a hotspot that is a signal of interest (SOI) or beacon component thereof with the FPA. Hotspot centroids can be estimated within a fraction of an FPA pixel by considering squares of four pixels and comparing their signal amplitudes. A multi-spot calculation is used to improve the position estimates of all of the hotspots by applying a Kalman filter to the hotspot position data and assuming that the relative hotspots positions are fixed. The calculation is periodically repeated to enable tracking of the SOI. Amplitude variability of the hotspots is accommodated by weighting the hotspot contributions according to their intensities. In embodiments, estimation error of the SOI centroid is less than a smallest dimension of the FPA pixels.

Abstract: A multi field of view (FOV) imaging system is disclosed. In one embodiment, a dual FOV imaging system includes a composite lens array including a first lens set positioned to focus a first type of FOV and a second lens set positioned to focus a second type of FOV and a composite focal plane array (FPA) including multiple focal plane arrays (FPAs). Further, the composite FPA is disposed at the first type of FOV and the second type of FOV for producing a seamless mosaic dual FOV image of a target region.

Abstract: A fluid cooled thermal management technique for a high-density composite focal plane array (CPFA) is disclosed. In one embodiment, a high density CFPA assembly includes a plurality of imaging dies mounted on a front surface of a printed wiring board (PWB) and a base plate. The base plate has a substantially matched coefficient of thermal expansion (CTE) to that of the high density CFPA. Further, the high density CFPA is disposed on a front side of the base plate. Furthermore, the base plate has a plurality of integral serpentine fluid flow channels configured to receive and circulate fluid and further configured such that the heat generated by the CFPA is transferred via conduction into the base plate and to the integral serpentine fluid flow channels and to the circulating fluid to dissipate the generated heat.

Abstract: A cross axis cable management system comprising a bird cage mechanism, a clock spring mechanism and a rolling loop mechanism positioned about a first axis, second axis and third axis of a gimbal mechanism respectively. Each mechanism provides defined channels and protective elements to prevent cable damage. The mechanisms also have one fixed end, one rotational end, and an optimized amount of slack for repeatable cable motion. The system effectively manages a large number of conventional and fiber optic cables while minimizing the friction or drag associated with the motion about the multiple axes and preventing cable damage and the resultant loss of performance.

Abstract: A vacuum compatible high-density electrical interconnect system for use in a vacuum environment is disclosed. In one embodiment, the vacuum compatible high-density electrical interconnect system includes a vacuum compatible base plate, a vacuum compatible printed wiring board (PWB) disposed on the vacuum compatible base plate and a vacuum compatible interposer module disposed in the vacuum compatible base plate. Further, the vacuum compatible PWB includes a plurality of components on a front side of the vacuum compatible PWB and a plurality of associated pads on a back side of the vacuum compatible PWB. In one exemplary embodiment, the vacuum compatible interposer module is disposed in the vacuum compatible base plate such that it operatively connects to the plurality of associated pads on the back side of the vacuum compatible PWB and further operatively connects to a plurality of pads of an external device that is disposed outside the vacuum environment.

Abstract: A composite focal plane assembly with an expandable architecture has a multi-layer, double-sided aluminum nitride (AlN) substrate and vertical architecture to achieve the dual function of focal plane and electronics backplane. Imaging dice and other electrical components are mounted and wire bonded to one surface and then direct backplane connectivity is provided on the opposing surface through a matrix of electrical contacts. In one embodiment, a flexible connector is sandwiched between the AlN focal plane and a FR-4 backplane is used to compensate for differences in coefficient of thermal expansion (CTE) between the AlN and commercially available high density circuit card connectors that are commonly manufactured from materials with CTE properties more closely approximating FR-4. In an alternate embodiment, the FR-4 and flexible connectors are eliminated by using high density circuit card connectors that are fabricated out of materials more closely matching the CTE of AlN.

Abstract: A deformable focal plane array (DFPA) for imaging systems is disclosed. In one embodiment, the DFPA includes a detection circuitry on one side. For example, the thickness of the DFPA is in a range of about 5 to 40 microns. In one exemplary embodiment, the DFPA when warped to a desired shape provides a substantially wider field of view (FOV) than a flat focal plane array (FPA).

Abstract: A fluid cooled thermal management technique for a high-density composite focal plane array (CPFA) is disclosed. In one embodiment, a high density CFPA assembly includes a plurality of imaging dies mounted on a front surface of a printed wiring board (PWB) and a base plate. The base plate has a substantially matched coefficient of thermal expansion (CTE) to that of the high density CFPA. Further, the high density CFPA is disposed on a front side of the base plate. Furthermore, the base plate has a plurality of integral serpentine fluid flow channels configured to receive and circulate fluid and further configured such that the heat generated by the CFPA is transferred via conduction into the base plate and to the integral serpentine fluid flow channels and to the circulating fluid to dissipate the generated heat.

Abstract: A deformable focal plane array (DFPA) for imaging systems is disclosed. In one embodiment, the DFPA includes a detection circuitry on one side. For example, the thickness of the DFPA is in a range of about 5 to 40 microns. In one exemplary embodiment, the DFPA when warped to a desired shape provides a substantially wider field of view (FOV) than a flat focal plane array (FPA).

Abstract: A vacuum compatible high-density electrical interconnect system for use in a vacuum environment is disclosed. In one embodiment, the vacuum compatible high-density electrical interconnect system includes a vacuum compatible base plate, a vacuum compatible printed wiring board (PWB) disposed on the vacuum compatible base plate and a vacuum compatible interposer module disposed in the vacuum compatible base plate. Further, the vacuum compatible PWB includes a plurality of components on a front side of the vacuum compatible PWB and a plurality of associated pads on a back side of the vacuum compatible PWB. In one exemplary embodiment, the vacuum compatible interposer module is disposed in the vacuum compatible base plate such that it operatively connects to the plurality of associated pads on the back side of the vacuum compatible PWB and further operatively connects to a plurality of pads of an external device that is disposed outside the vacuum environment.

Abstract: A cross axis cable management system comprising a bird cage mechanism, a clock spring mechanism and a rolling loop mechanism positioned about a first axis, second axis and third axis of a gimbal mechanism respectively. Each mechanism provides defined channels and protective elements to prevent cable damage. The mechanisms also have one fixed end, one rotational end, and an optimized amount of slack for repeatable cable motion. The system effectively manages a large number of conventional and fiber optic cables while minimizing the friction or drag associated with the motion about the multiple axes and preventing cable damage and the resultant loss of performance.

Abstract: A multi field of view (FOV) imaging system is disclosed. In one embodiment, a dual FOV imaging system includes a composite lens array including a first lens set positioned to focus a first type of FOV and a second lens set positioned to focus a second type of FOV and a composite focal plane array (FPA) including multiple focal plane arrays (FPAs). Further, the composite FPA is disposed at the first type of FOV and the second type of FOV for producing a seamless mosaic dual FOV image of a target region.

Abstract: A passive heat exchanger for gimbal thermal management is disclosed. In one embodiment, a thermal management system includes one or more electronics and/or sensor equipment. Further, the thermal management system includes a thermally conductive shell configured to house the electronics and/or sensor equipment. Furthermore, the thermally conductive shell includes an external surface and an internal surface. In addition, at least some portion of the external surface and the internal surface of the thermally conductive shell include an extended surface configured to reduce thermal resistance between an interior region of the thermally conductive shell and ambient air.

Abstract: In the subject three-axis pointing system, the elevation and tip mirror axes are permanently mounted with their rotation axes orthogonal to each other to eliminate gimbal lock over the hemisphere, to avoid high accelerations as the zenith or nadir pointing directions are approached, and to provide optimal two-axis beam pointing control.

Abstract: In the subject three-axis pointing system, the elevation and tip mirror axes are permanently mounted with their rotation axes orthogonal to each other to eliminate gimbal lock over the hemisphere, to avoid high accelerations as the zenith or nadir pointing directions are approached, and to provide optimal two-axis beam pointing control.

Abstract: A kink suppression technique is disclosed in which optical characteristics of a distributed feedback laser diode's resonant cavity are controlled to preferentially prevent establishment of higher order lateral modes. This results in increased kink powers and thus the useful power range of the device. Specifically, an optical layer, preferably silicon or titanium, is disposed along the optical axis, on the etched upper cladding layer, and on both sides of the ridge.

Abstract: A kink suppression technique is disclosed in which optical characteristics of a distributed feedback laser diode's resonant cavity are controlled to preferentially prevent establishment of higher order lateral modes. This results in increased kink powers and thus the useful power range of the device. Specifically, an optical layer, preferably silicon or titanium, is disposed along the optical axis, on the etched upper cladding layer, and on both sides of the ridge.

Abstract: A single-frequency semiconductor laser diode structure and a method for its fabrication. The structure includes a built-in etalon, which limits the frequency of operation of the device to a very narrow frequency band. For an edge-emitting diode, the etalon is formed over a cleaved end face of the semiconductor diode structure, and light is emitted from an opposed cleaved end face. For a surface emitting diode, the etalon is formed as an additional plurality of layers between a plurality of semiconductor layers forming the diode and a substrate on which the structure is formed. Transverse channels formed in the structure have side surfaces that act as mirrors, at least one of which is angularly inclined to the plane of the active region, to reflect light through the etalon layers and out through a parallel exterior surface of the structure. Multiple surface emitting lasers may be arrayed in closely spaced relation to each other, to form a powerful light emitting array.