Abstract: A laser telescope is provided for reducing undesired laser thermal lensing effects which would otherwise impair the intensity and quality of a laser beam passing therethrough. An outer barrel is mounted in a chamber within a housing by ball bearings which hold the outer barrel longitudinally fixed but permits rotation of the outer barrel about its longitudinal axis. An inner barrel is coaxially situated within the outer barrel and includes a threaded outer surface which is threaded into a threaded inner surface of the outer barrel. A first lens is mounted adjacent one end of the chamber and a second lens is mounted in the inner barrel. A laser beam is directed through the laser telescope along the common axis of the chamber, the outer barrel, and the inner barrel. The lens spacing in the barrels is sensed and actuates a drive motor in proportion to the error between the sensed lens spacing and the desired lens spacing.

Abstract: An improved photocathode for use in a night vision system, comprising a glass face plate, an AlInAs window layer having an anti-reflection and protective coating bonded to the face plate, an InGaAs active layer epitaxially grown to the window layer, and a chrome electrode bonded to the face plate, the window layer, and the active layer providing an electrical contact between the photocathode and the night vision system, whereby an optical image illuminated into the face plate results in a corresponding electron pattern emitted from the active layer.

Abstract: An output beam combining apparatus for recombining diverging output beams from a ring laser. One preferred embodiment of the present invention includes a first planar mirror mounted to an exterior surface of a ring laser output mirror and having a reflective coating oriented generally perpendicular to the output mirror along with a second planar mirror disposed adjacent to the first mirror and having a reflective coating oriented perpendicular to the reflective plane of the first mirror. In use a first output beam from the ring laser is reflected back to the rear surface of the ring laser output mirror along a path parallel to but displaced from its initial path. This return beam is then reflected off of the rear surface of the output mirror along a path that is collinear with a second output beam from the ring laser so as to form a combined beam that is directed to a suitable detector.

Abstract: Dispersion in a multi-oscillator cavity is equalized by processing information extracted from the laser beams within the cavity to generate an error signal representative of dispersion bias, and applying a bias control signal to the cavity in such a way as to null the error signal. The bias control signal is preferably a magnetic field applied to the gain medium of the cavity by passing a corresponding current through a coil surrounding the medium. In exemplary embodiments, the laser beams are modulated by modulating the applied magnetic field and/or the path length of the cavity.

Abstract: A laser writing apparatus includes a laser light source which directs an expanded beam of laser light onto a two-dimensional phase grating. The phase grating splits the beam into a two-dimensional array of individual bundles of collimated light or beamlets. Each individual row of beamlets is reflected by a single strip mirror toward the surface on which a pattern is to be written. By moving the surface under the beams at a selected angle, multiple parallel lines can be written simultaneously on the surface.

Abstract: Method and apparatus for reducing rotational bias error in a ring laser. The method includes the steps of varying a portion of an optical path for laser beams that emerge from a ring laser cavity along divergent paths and are subsequently combined along a common path to a detector. The apparatus of one embodiment includes a movable mirror positioned to intercept the laser beams emerging from the ring laser cavity before combination along a common path. The movable mirror may be piezo-electric transducive elements configured to bend on application of a voltage. The piezo-electric elements are provided with a reflective region that is positioned to redirect the laser beams from the ring laser back to an output coupling mirror so that re-reflection from the output mirror redirects the laser beams back into a beam combining optical element. In an alternative embodiment the detector is periodically displaced along an access parallel to the common path of the laser beam.

Abstract: A triaxial multioscillator for operation in accordance with a mode of operation requiring the imposition of a substantially uniform axial magnetic field on the gain region of each lasing cavity. An integral frame of glass ceramic material has a rhombic dodecahedral shape and includes three closed lasing cavities, each formed of four straight segments. The cavities include three mutually parallel segments, one from each cavity, that are regularly spaced on a circle perpendicular to the axis of the frame. An internal cathode and six anodes are associated with the frame to provide gain in each of such three segments. The frame is positioned within a closed cylindrical element of soft iron composition by means of a fixture. The fixture positions magnets adjacent the top and bottom of the element to generate parallel lines of magnetic flux therein.

Abstract: A laser diode mount having a thermal coupling for a laser diode heat sink utilizes a shape memory alloy in the maintaining of laser diode arrays within an operational temperature bandwidth. A diode carrier member holds a laser diode array and is movably attached with posts to a heat sink and spaced by a variable air gap from the heat sink thermal pad. The diode carrier member can move on the posts to vary the gap and a shape memory alloy member is shaped as a coil or spring and coupled between the diode carrier member and the heat sink thermal pad for use in varying the gap therebetween. The shape memory alloy member works against a conventional spring. The heat sink thermal pad may be part of a forced convection heat sink.

Abstract: A cooled stray light baffle for use in an imaging system such as an infrared camera is disclosed. The baffle includes a tapered shroud portion which is shaped to just enclose the envelope of light rays which pass through the baffle. That is, space between the envelope of light rays and the inner surface of the baffle is minimized. This results in minimization of the overall surface area and mass of the baffle, which in turn results in a minimization of the refrigeration load of the system. The lower refrigeration load requires a smaller refrigerator which results in reduced system size, power consumption, vibration, cool-down time and cost of operation. The outer surface of the baffle is covered with a reflective material to reflect light photons. The inner surface is roughened and blackened to absorb stray light photons which enter the baffle.

Abstract: A sensor coil for a fiber optic gyroscope. The coil is formed on a spool of carbon composite material or of another material whose coefficient of thermal expansion approximates that of the overlying windings of the glass optical fiber. The windings are potted in an adhesive material. Various bias effects are addressed by the coil design. The close matching of the thermal expansion characteristics of the spool and the fiber windings as well as proper selection of the coil potting material minimize the Shupe-like bias caused by thermal stress that would be otherwise exerted by a standard metallic spool. By careful selection of potting material (particularly its modulus of elasticity) vibration-induced bias, coil cracking, degradation of h-parameter and temperature-ramp bias sensitivity are also minimized.

Abstract: A monolithic triaxial ring laser gyroscope includes three orthogonal ring cavities, the optical path length of each of which is independently controllable. Three planar ring cavities are formed within a frame that is shaped into the form of a rhombic dodecahedron. A mirror is fixed to each of the twelve faces of the frame for directing the counter propagating light beams within the three orthogonal cavities. Anodes which communicate with the cavities through bore holes are fixed to predetermined surfaces of the frame while three cathodes are positioned at flattened portions of preselected vertices of the dodecahedron and located in such a way as to eliminate undesired bias resulting from Fresnel-Frizeau effects.

Abstract: A night vision device with a modular assembly includes an image intensifier module or assembly, which includes an image intensifier tube and a power supply. The image intensifier tube receives low-level light from a scene too dark to be viewed with the unaided eye, and provides a visible representative image of the scene in phosphor yellow/green light. The power supply receives low-voltage power from a source, such as a battery, and provides power at voltages appropriate for operation of the image intensifier tube. The module includes a separable high-voltage connector for electrically connecting the power supply to the image intensifier tube. According to a preferred embodiment of the invention, the connector includes structure for physically connecting the power supply and image intensifier tube in separable nested relationship while also providing environmental protection to electrical connector features of the module.

Abstract: Disclosed herein is a Solid State Split-Gain Multioscillator Ring Laser Gyroscope comprising, in a preferred embodiment, a solid state Nd:YAG crystal body defining a non-planar resonator path. Magnetic sources are provided which effectuate the Split-Gain Selective Mode Suppression Phenomena. Total internal reflection along facets of the crystal or glass allow reduced cost during manufacture of the Gyroscope. An alternative embodiment includes a solid state active medium on a chip, allowing the resonator path to be primarily lying in a glass monolithic compact solid state frame.

Abstract: A light-weight night vision device includes a housing carrying an objective lens through which low-level light from a scene to be viewed is received. The housing carries an image intensifier tube receiving the low-level light from the objective lens, and providing in response an image representative of the scene. An eye piece carried by the housing provides a user of the device with an view of the representative image. The housing includes a light-weight portion which both carries the objective lens and partially houses the image intensifier tube. This light-weight housing portion also serves to shield the image intensifier tube from radio frequency and electrostatic interference.

Abstract: An acceleration insensitive interferometric hydrophone sensor having increased sensitivity comprises a rigid cylindrical support mandrel that is coaxial with and between thin walled sense and reference mandrels. Flanges on the reference and support mandrels form air filled cavities above and below optical reference and sense fiber windings, respectively, that are symmetrically wound on associated mandrels. The walls of the sense and reference mandrels are thin so that they both respond to the same incident acoustic wave signal although 180.degree. out-of-phase. A central collar on the support mandrel provides an acceleration insensitive location for making attachment to the hydrophone. In another embodiment, the reference mandrel is much thicker than the sense mandrel and cavities supporting the sense fiber are caused to operate as acoustic impedance mismatches for rendering the reference fiber winding substantially insensitive to and acoustically decoupling it from an incident acoustic pressure wave signal.

Abstract: A binocular night vision device includes a pair of night vision monocular scopes which adjustably depend from a support frame in front of a user's eyes. The support frame includes an interpupillary distance adjustment mechanism which allows non symmetrical placement of the monocular scopes to better achieve binocular vision with depth perception. Also, the adjustment mechanism allows adaptive duplicative use of identically the same component parts of the device on both the left and right sides of the support frame so that the number of different parts required for the device is reduced.

Abstract: A path length controller for a ring laser gyro wherein the path length is dithered by dithering of one or more of the mirrors and the mirror or mirrors are controlled by a servo which is selectively biased in response to the servo signal to keep the mirror or mirrors in a position to support the largest amplitude of the principal mode of laser oscillation.

Abstract: A cathode heater includes a patterned conductor embedded within a dielectric substrate. The ceramic substrate has a pair of conductors over the respective surfaces thereof to provide electrical contact for the heater. To assemble the substrates having the conductors, the substrates and printed conductive patterns are fired to provide a composite multi-layer ceramic heater which can be used to heat cathode electrodes in microwave tubes such as travelling wave tubes.