Abstract: A spacecraft telescope door (10) adapted for use with remote sensing devices requiring optical and infrared calibration. The door (10) includes a first calibration surface (24) disposed on a first panel (14) for providing a radiant temperature reference for infrared calibrations. A second calibration surface (26) is disposed on a second panel (12) for providing an absolute radiance reference for optical calibrations. A panel hinge (16) controls the relative position of the panels (12,14) with respect to each other, and an aperture hinge (20) controls the relative position of the panels with respect to the aperture (28). In a specific embodiment, the first surface (24) is painted with chemglaze Z306, a highly emissive paint with a low reflectance for facilitating infrared calibration. The second surface (26) is painted with YB71, a diffuse reflective paint for facilitating optical calibration.

Abstract: An improved imaging technique is disclosed wherein an output from an IR-FPA (16) corresponds to image motion, wherein a scene image stays correlated with the IR-FPA readout, and wherein non-uniformities (e.g., fixed pattern spatial noise) are uncorrelated from frame to frame. The uncorrelated fixed pattern spatial noise is identified and removed by a signal processor, such as a SB-NUC block (24). The scene image is scanned over the IR-FPA by a dither mirror (14) in synchronism with the movement of a frame of pixels (17) on the IR-FPA. Electronics (16a, 16b, 30, 32, 34) are included on the IR-FPA for controlling the scanning and read out of pixels within a currently selected frame.

Abstract: An optical beam regenerator includes a plurality of optical fibers into which an input beam is directed. The optical fibers are positioned to rearrange portions of the input beam to generate an output beam having a uniform or other prescribed distribution of irradiance. To further smooth the irradiance distribution of the output beam, the beam can be directed through a Kohler illumination system.

Abstract: A vacuum system (20) includes an enclosure (22) having a vacuum-tight wall (26) and an internally threaded aperture (66) through the wall (26). A tip-off fitting (24) has a base (50) with a bore (52) therethrough, a hollow tube (62) fixed to the base (50) with a vacuum-tight seal, such that an interior (64) of the tube (62) is in communication with the bore (52) in the base (50), and an external thread (58) on the exterior of the base (50). The external thread (58) on the exterior of the base (50) is dimensioned to threadably engage the internal thread (68) on the aperture (66). There is a disengageable vacuum sealant (70) such as a layer of indium metal between the external thread (58) of the base (50) and the internal thread (68) of the aperture (66). The vacuum system (20) is evacuated through the tip-off fitting (24) and sealed by closing off the hollow tube (62).

Abstract: A miniature grating drive device (216) for accurately and precisely positioning a grating (236) of a projection Moire topography measurement system where the Moire topography measurement system is included as part of a hand-held medical instrument for providing surface measurements of inaccessible living membranes. The drive device (216) includes two separate piezoelectric bimorph actuators (248, 256) for positioning the grating (236) at three precise locations. The first piezoelectric bimorph actuator (256) accurately positions the grating (236) at a first location, and the second piezoelectric bimorph (248) actuator accurately positions a base (232) on which the first piezoelectric actuator (256) is attached to move the grating (236) to a second location.

Abstract: A fiber-based delivery system and method for delivering pulsed high power optical radiation (14) over longer fiber lengths than prior fiber-based systems comprises a fiber bundle (10) and a beam launcher (12) that directs a high power optical beam (14) to an input end (18) of the fiber bundle (10), and distributes it over the individual fibers (22) in the bundle. The number of fibers (22) is large enough so that substantially all of the individual fibers (22) are subjected to an optical intensity level below that required to induce substantial nonlinear optical losses. In addition, the diameters of the individual fiber cores (34) are small enough so that the modal dispersion experienced by the optical beam (14) does not exceed approximately 80 ns/km. In a preferred embodiment for transmission of pulsed 1.06 micron light, the fiber bundle (10) comprises 96 individual fibers (22), with respective core (34) diameters of approximately 600 microns, that are encapsulated in a jacketed adhesive (30).

Abstract: An improved system (30) for measuring surface aberrations of concave cylindrical surfaces. In the illustrative embodiment, the invention includes a transmission flat (20), an interferometer (32), and a surface to be measured (28). The transmission flat (20) is a transparent disc that is placed between the interferometer (32) and the surface (28) to be measured. An electromagnetic wave (33,34,36,37) is generated by the interferometer (32), and is directed through the transmission flat (20). The wave (41) bounces off the surface (28) to be measured and is retro-reflected off a first surface (26) of the transmission flat. The electromagnetic wave (42) returns to the opposite side of the surface (28) under test. The wave (43) then bounces off the surface (28) under test and passes through the transmission flat (20). The wave (43) interferes with light (39) that is reflected from a reference surface (26) of transmission flat (20) on a first bounce.

Abstract: A differential spectrometry system detects very narrow-band spectral features, while providing much higher optical transmittance and signal-to-noise ratios than prior optical-filter-based spectrometer systems. A plurality of light detectors (10a, 10b) detect light that falls within respective wide wavebands. The wide wavebands have overlapping and non-overlapping portions, one of which is the desired narrow waveband. The detector outputs are operated upon to produce an output signal (22) which includes substantially only the desired narrow waveband. In the preferred embodiment, the light detectors (10a, 10b) are implemented with a pair of optical detectors (30a, 30b) and respective optical interference filters (24a, 24b). The filters have substantially identical cut-off wavelengths (.lambda..sub.2) and cut-on wavelengths that are shifted by .DELTA..lambda. with respect to each other (.lambda..sub.1 and (.lambda..sub.1 +.DELTA..lambda.), respectively).

Abstract: An infrared (IR) microlens array has a plurality of microlenses (12) aligned with respective IR detector array pixels (6) to focus incoming IR radiation onto the pixels (6) to improve the efficiency of IR detection, and a gas molecule getter grating (14) inside a vacuum-sealed Dewar assembly that houses the detector array (4) increases the surface area of the getter (15) to improve the efficiency of removing residual gas molecules from the Dewar assembly.

Abstract: An optical device assembly includes a planar optical filter and a planar sensor having an optically active area. The optical filter and the sensor are joined together with a gap therebetween by a metallic bump extending between the optical filter and the sensor. The metallic bump, which is preferably indium, is positioned at a location outside of the optically active area of the planar sensor. The metallic bump is preferably formed by vapor depositing an indium subbump on the optical filter and another indium subbump on the planar sensor, in each case outside of their optically active areas, and thereafter pressing the two subbumps together to complete the bonding.

Abstract: A highly integrated thermal sensor (10) is responsive to radiation having wavelengths within a predetermined band of wavelengths. The sensor, which may be a thermopile, is comprised of a substrate (16) comprised of at least one semiconductor material. The substrate includes at least one active region disposed within a first surface of the substrate. The sensor further includes a plurality of thermally-responsive junctions (HJ, CJ) between dissimilar materials (22, 24) that are disposed within the at least one active region, wherein at least one of the thermally-responsive junctions is a hot junction. The hot junction is thermally isolated from the substrate by being suspended from the substrate on dielectric bridges or, in another embodiment, by a thermally insulating and patterned polymer. In a backside illuminated embodiment of this invention the sensor further includes an optical cavity (26) formed within a second surface of the substrate in registration with the active region.

Abstract: A scanning detection system. The inventive system includes a detector arrangement for scanning a target surface over a predetermined angular range and providing a plurality of sampled signals in response thereto. The detector outputs are sampled and aggregated to provide a first output having a constant spatial resolution independent of the scan angle of the detector. The detector outputs are also aggregated to provide a second output having fine radiometric sensitivity. In a specific implementation, constant resolution is achieved by co-adding a variable number of adjacent detector samples where the number of adjacent samples co-added is dependent on the scan angle. Fine radiometric sensitivity is achieved by co-adding a fixed number of adjacent samples. Thus, dual capabilities of constant resolution and high sensitivity are achieved in a cost effective manner.

Abstract: A flip-chip assembly and method for reducing the stress in its metal interconnections resulting from thermal mismatch includes a detector that has a radiation sensitive circuit on a substrate that is flip-chip connected to a layer of semiconductor material that is provided with a readout circuit. The substrate has a thermal coefficient of expansion (TCE) greater than the semiconductor layer such that operating the detector over a predetermined temperature range would stress the flip-chip connections. A first compensation layer on the readout chip has a TCE greater than the substrate's, and a second compensation layer on the first layer has a TCE approximately equal to the semiconductor layer's. The materials and thicknesses of the compensation layers are selected such that the TCE of a composite structure that includes the semiconductor and compensation layers is approximately equal to the substrate's TCE to avoid the stress over the predetermined temperature range.

Abstract: Methods are disclosed for fabricating a monolithic array of radiation detectors and associated readout circuits, as are monolithic arrays fabricated by the methods.

Abstract: The present invention involves a method for bonding together molecularly homogeneous objects including optical and semiconductor members. In particular, such method involves forming micro-thin grooves using high precision laser ablation in one of two surfaces to be bonded together. An adhesive is then flowed into such a groove to form chemical bonding of the members. Such bonding essentially eliminates the formation of an adhesive layer in the interface between the bonding surfaces allowing optical contacting in addition to the chemical bonding.

Abstract: An integrated photovoltaic detector includes a reference photovoltaic detector and an active photovoltaic detector in a series connection. The reference detector produces a dark current that opposes the active detector's dark current. The active detector effectively masks the reference detector from incident illumination so that the active detector produces photocurrent but the reference detector does not. The band gap of the reference detector is preferably matched to the active detector so that their dark currents are substantially matched over a temperature range. As a result, the current read out of the integrated detector at the series connection is approximately equal to the photocurrent generated by the active detector. This improves the detector's SNR, signal resolution, and useful operating temperature range.

Abstract: The light receiving or back-side surface (22) of an indium antimonide (InSb) photodetector device (10) substrate (12) is cleaned to remove all native oxides of indium and antimony therefrom. A passivation layer (26) is then formed on the surface (22) of a material such as silicon dioxide, silicon suboxide and/or silicon nitride which does not react with InSb to form a structure which would have carrier traps therein and cause flashing. The device (10) is capable of detecting radiation over a continuous spectral range including the infrared, visible and ultraviolet regions.

Abstract: A photoresponsive device (10) includes a body comprised of semiconductor material comprised of elements selected from Group IIB-VIA; and at least one electrically conductive contact pad (20) formed over a surface of the semiconductor material. The at least one electrically conductive contact pad is comprised of metal nitride, such as MoN, and serves as a diffusion barrier between an Indium bump (22a, 22b) and the underlying semiconductor material. A passivation layer (18), such as a layer of wider bandgap CdTe, can be formed to overlie the surface of said semiconductor material. A p-n junction is contained within a mesa structure (10a) that comprises a portion of an n-type base layer (14) and a p-type cap layer (16). A first contact pad is disposed over the cap layer and a second contact pad is disposed over the base layer.

Abstract: A capacitor (20) is fabricated using a ferroelectric material (28) such as a layered perovskite material of the Aurivillius family. The capacitor (20) has a positive temperature coefficient (PTC) of capacitance. When used in an electrical device other than a memory device in place of a conventional capacitor, the PCT capacitor (20) provides inherent temperature compensation of the signal of the device when the device is operated at different temperatures below the Curie temperature of the ferroelectric material.

Abstract: A reflective scanning telescopic system comprises: a primary ellipsoidal mirror for collecting incoming light, a secondary hyperbolic mirror for reflecting the light collected by the primary mirror axially through the primary mirror, a tertiary ellipsoidal mirror, disposed behind the primary mirror for receiving the light from the secondary curved mirror, and a double bounce fold mirror for directing light reflected from the first fold mirror to the tertiary mirror and for reflecting light from the tertiary mirror past the first fold mirror to a light imaging system. Ideally, the telescopic system is mounted on a substantially rigid optical bench on a gimbal for supporting the optical bench and enabling the optical bench to scan in two dimensions by pivoting along roll and pitch axes.