Abstract: Surface-emitting distributed feedback (SEDFB) lasers having a curved grating with a shape that produces good beam quality. A preferred shape is one for which the grating curves away from the center of the gain region of the laser. The use of the curved grating of the present invention produces good beam quality from broad area SEDFB lasers with high power and high efficiency. The present invention overcomes self-induced filament formation and dynamic instabilities that limit achievable beam quality. The present invention provides for a holographic method for fabricating curved gratings for the SEDFB lasers that is consistent with laser batch processing.

Abstract: The present invention provides a lens holder (14) for a lens under test (26) in an in-line hologram interferometric test apparatus (10) which includes a flat reflective surface (34) for rotationally positioning the lens under test (26) and a parabolic reflective surface (32) for translationally positioning the lens under test (26). According to this configuration, the lens holder (14) is translationally positioned using the parabolic reflective surface (32) to reflect radiation to a focal point (24) along the hologram (22). The hologram (22) returns the radiation to the parabolic reflective surface (32) which reflects it back to the interferometer (12) at a precise distance and position using normal interferometric techniques. The lens under test (26) is rotationally positioned by pivoting the lens holder (14), both in tip and in tilt, so that the flat reflective surface (34) is nulled to the interferometer (12).

Abstract: A steering mechanism (17) in which axial motion of an optical structure (12) is constrained electrically through a closed loop servo control system. The steering mechanism includes three magnetic actuators (19a, 19b, 19c) each having a push rod (20a, 20b, 20c) magnetically coupled thereto for being translated by the magnetic actuator along a translation axis (A). Each of the push rods has an end coupled to a peripheral region (1a, 1b, 1c) of the optical structure for exerting a displacing force thereon in response to the push rod being translated along the translation axis. A non-contact displacement sensor (10c) provides a feedback signal for the closed loop servo control system.

Abstract: The present invention provides a lens holder (14) for a lens under test (26) in an in-line hologram interferometric test apparatus (10) which includes a flat reflective surface (34) for rotationally positioning the lens under test and a spherical reflective surface (32) for translationally positioning the lens under test (26). According to this configuration, the lens holder (14) is translationally positioned using the spherical reflective surface (32) to reflect radiation back to the interferometer (12) at a precise distance and position using normal interferometric techniques. The lens under test (26) is rotationally positioned by pivoting the lens holder (14), both in tip and in tilt, so that the flat reflective surface (34) is nulled to the interferometer (12). Thereafter, the lens holder (14) is correctly positioned relative to the hologram (22) and interferometer (12) so that when the lens under test (26) is seated on the lens holder (14), its aspherical shape can be tested.

Abstract: A linear displacement device (1) is provided with a lead screw (24) having a helical threaded portion (74) and a roller nut assembly (10). The roller nut assembly (10) includes a housing (50) having openings (52, 54) for receiving the lead screw (24) therethrough. A pair of bearings (56, 58) are supported within said housing (50). The bearings (56, 58) each have an inner race (60), an outer race (62) and a plurality of balls (64) disposed between the inner and outer races (60, 62). A threaded member (66) is supported radially inward of said inner race (60). Threaded member (66) includes a plurality of concentric grooves (72) for engaging the flank (68, 72) of a helical threaded portion (74) of the lead screw (24) and a crest contacting portion (70) for engaging a crest (76) of the helical threaded portion (74) of the lead screw (24). A spring member (68) is provided for preloading the bearing (56, 58).

Abstract: The present invention provides a measuring apparatus (10) for centering and determining wedge error of an optical element (12) under test. The measuring apparatus (10) preferably includes a lens holder (16) for supporting the optical element (12) to be tested. The lens holder (16) is rotatably supported on an air bearing (68) having an axis such that the lens holder (16) may be rotated about the axis. A first sensor (18) is located proximate the lens holder (16) for measuring the wedge characteristics of the optical element (12). The first sensor (18) is movable in a horizontal, vertical and rotatable direction such that the first sensor (18) may be positioned to a predetermined distance from the optical element (12) at a preselected angle. A second sensor (20) is located proximate the lens holder (16) for measuring centering characteristics of the optical element (12).

Abstract: A continually supported assembly capable of being space launched includes a base and a thin optical substrate having a light collecting first surface and an opposite rear surface. An elastically coupling medium couples the rear surface of optical substrate and said base to one another. At least one force-coupled actuator is interspersed within said elastic coupling medium for controllably altering the shape of said optical substrate.

Abstract: This invention pertains to a method for processing readout integrated circuits, and to a readout integrated circuit (10) that is processed in accordance with the method. The method includes a first step of providing a plurality of individual readout circuits each having a substrate (12) and at least one layer (14) constructed to have active circuitry that overlies a first surface (12a) of the substrate. Each of the readout integrated circuits has an associated amount of non-flatness or bowing due at least in part to a first force exerted on the substrate by the at least one layer of circuitry. A next step sorts the plurality of readout integrated circuits into a plurality of groups (A, B, C), wherein members of a group have a similar amount of non-flatness.

Abstract: A system (50) for separating and combining frequency bands (64, 74, 78) from a beam (62) of electromagnetic energy adapted for use with a beam of white light (62) having a first (64), second (74) and third (78) frequency band. The inventive system (50) includes a first surface (58) for transmitting the first frequency band (64) and reflecting the second (70, 78) and third (70, 74) frequency bands. A second surface (60) reflects the second frequency band (74) and transmits the third (78) frequency band. A transparent support structure (52, 54, 56) supports the first surface (58) and the second surface (60) in a pre-determined orientation that provides for a low angle of incidence (66, 72) of electromagnetic energy impinging on the first surface (58) and the second surface (60) to minimize undesirable polarization effects. In a specific embodiment, the angle (66, 72) is 22.5 degrees.

Abstract: An interferometer or spectrometer having a short stroke reactionless drive mechanism is disclosed. The interferometer includes a housing, and a beamsplitter for reflecting an input beam along a fixed optical path and for transmitting the input beam along a scanned optical path. A nonmoving reflecting arrangement is disposed along the fixed optical path and includes first and second nonmoving mirrors disposed to reflect the input beam multiple times therebetween, and a backreflecting device disposed at a final bounce position of the input beam to return the optical beam back to the beamsplitter. A scanning mechanism is disposed along the scanned optical path that includes third and fourth mirrors supported by flexible members or flexure blades that are coupled to the housing, and a backreflecting device at a final bounce position of the input beam to return the optical beam back to the beamsplitter.

Abstract: A video buffer of a focal plane array (FPA) electrical interface module is presented for providing output capacitance cancellation. The buffer has a capacitance cancellation stage (50) for receiving an analog signal produced by a FPA. The cancellation stage (50) includes an amplifier having a gain greater than unity for amplifying the analog signal and positive feedback capacitor for reducing power requirements and providing an increased pixel rate for the system. A dc restoration stage (52) is included for setting the analog signal to a dc level that is required by an external system and a line driving stage (54) for driving a video cable from the buffer to the external components of the system.

Abstract: An electrically conductive infrared (IR) window (10) has high transmittance at IR wavelengths and includes an electrically conductive protective layer (14) which is direct bonded to a substrate (16) at room temperature without adhesive therebetween. The protective layer (14) and substrate (16) are transparent at IR wavelengths. The protective layer (14) and the substrate (16) are annealed at a bonding temperature above room temperature to enhance the bond strength. The protective layer (14) preferably comprises at least one of doped silicon and doped gallium arsenide and has a conductivity between 1 and 500 ohms/square. The substrate (16) preferably comprises at least one of zinc sulfide, zinc selenide, germanium, and gallium arsenide. The protective layer (14) and substrate (16) should be made of different materials with different coefficients of thermal expansion to allow debonding by heating above the bonding temperature.

Abstract: A measurement device (2) for measuring a collimated wave front through a lithographic lens includes a radiant energy source (4), a lens group (6) for collimating light emitted from said radiant energy source and directing said collimated light (7) toward a reference surface (10). A first binary optic (12) disposed in line with said collimated light and located adjacent to an input conjugate of a lens under test. A second binary optic (18) is arranged in a spaced relationship and in line with said first binary optic for retroreflecting light passing through a lithographic lens disposed between said first and second binary optics. A recording system (8,9) is provided for recording an interference with the light retroreflected-reflected back through said lens and through said reference surface.

Abstract: An imaging device (10, 10') has a plurality of unit cells (11) that contribute to forming an image of a scene. The imaging device includes a layer of wide bandgap semiconductor (18) material (e.g., silicon) having photogate charge-mode readout circuitry (20, 22, 24), such as CCD or CMOS circuitry, disposed upon a first surface of the layer. In one embodiment a second, opposing surface of the layer is bonded at a heterojunction interface or atomic bonding layer (16) to a surface of a layer of narrower bandgap semiconductor material (e.g., InGaAs or HgCdTe), that is selected for absorbing electromagnetic radiation having wavelengths longer than about one micrometer (i.e., the NIR or longer) and for generating charge carriers. The generated charge carriers are transported across the heterojunction interface for collection by the photogate charge-mode readout circuitry.

Abstract: An imaging device (10) has a plurality of unit cells that contribute to forming an image of a scene. The imaging device includes a layer of semiconductor material (16), for example silicon, that has low noise photogate charge-mode readout circuitry (20, 21, 26, 28) (e.g., CCD or CMOS readout circuitry and structures) that is disposed upon a first surface (18) of the layer. A second, opposing surface of the layer is a radiation admitting surface of the layer. The layer has a bandgap selected for absorbing electromagnetic radiation having wavelengths shorter than about one micrometer and for generating charge carriers from the absorbed radiation. The generated charge carriers are collected by the photogate charge-mode readout circuitry. A thermal sensing element (22) is disposed above and is thermally isolated from the first surface of the layer. The thermal sensing element may be, by example, one of a bolometer element, a pyroelectric element, or a thermopile element.

Abstract: This invention teaches a method for fabricating an array (1) of pyroelectric detectors (10), and further teaches an array (1) of pyroelectric detectors (10) that include a bismuth layered compound. The array has a substrate (12) and a plurality of pyroelectric detector sites disposed over a surface of the substrate. Each of the pyroelectric detector sites is constructed to have a first electrode (16); a second electrode (20); and a thin layer (18) containing a bismuth layered compound that is interposed between and electrically coupled to the first and second electrodes. In one embodiment the thin layer is comprised of Y1 material (SrBi.sub.2 Ta.sub.2 O.sub.9), while in another embodiment the layer is comprised instead of YZ material (SrBi.sub.2 Nb.sub.2-x Ta.sub.x O.sub.9).

Abstract: A calibration system and method for a display optical system including a projector and a projection screen. A calibration camera is inserted between the projector and the screen to receive the radiation directly from the projector. The image focused by the camera lens is captured by a charge-coupled device, and processed by a controller. The result is fed back to the image generator of the projector for further improvement in the image quality.

Abstract: This invention pertains to a method and apparatus for inscribing a pattern into a surface of a substrate, such as a sheet of glass. The method includes the steps of providing a Nd:YAG laser (12) having a characteristic output wavelength of 1.06 micrometers; providing a glass substrate (18) that is substantially transparent to the characteristic output wavelength; and applying a layer of material, such as a layer of tape (16), to a surface (18a) of the substrate. The layer of material is selected so as to strongly absorb the characteristic output wavelength. A next step focuses (14) an output of the laser into a spot (12c) at or near to an interface between the layer of material and the surface of the substrate. A further step translates (20) the surface relative to the spot. The layer of material absorbs the output of the laser and is heated thereby to a temperature sufficient for inscribing the surface underlying the spot.

Abstract: An optical system is coupled between a one-dimensional line image and a two-dimensional detector array. The line image is segmented and reimaged onto respective image cells of the detector array, each image cell being a row of detector cells. The optical system positionally segments the line image into lengths of a predetermined length. The predetermined length of the segments optically fit within the width of image cells within the array. The optical system reimages the line segments to image cell positions on the detector array. The optical system preferably employs diffractive (binary) optic elements.

Abstract: Clusters, such as Argon gas clusters, provided by a cluster source are doped in a water pick-up cell, and subsequent electron impact ionization of the doped clusters in a mass spectrometer or gas analyzer produce ionized cluster fragments that retain water. Water is supplied under pressure to the pick-up cell disposed within a vacuum chamber, and the water pressure is metered by a metering valve and monitored by a pressure gauge. A vacuum pump is coupled to the vacuum chamber that generates a vacuum within the vacuum chamber and pick-up cell. Interaction between the gas clusters and the water in the pick-up cell produces doped clusters, some of which retain water. The electron impact ionized doped cluster fragments are analyzed using the mass spectrometer or gas analyzer permits determination (detection) of the mean cluster size of the clusters.