Abstract: A hydrophone includes a plurality of hydrophone components separated by finite spacings and interconnected to provide a single output signal. Each hydrophone component is based upon a single-mandrel design in which a cylindrical body is apportioned into sensing and reference sections. The sensing sections comprise coaxial arrangements of pliant inner and outer cylinders separated by an annular airspace while the adjacent reference sections comprise solid-walled cylinders. Finite separation distances between the hydrophone components result in reduced flow noise occasioned by increased sensing area while detection sensitivity is maintained.

Abstract: A method and apparatus for pumping a coolant through a laser cavity to cool the laser. The apparatus has a titanium housing and a casing containing a rotatable titanium hollow shaft. A titanium impeller is located at one end of the shaft within the housing and rotates with the shaft to pump the fluid through a laser. Disposed within casing and attached to the shaft are a plurality of permanent magnets. External to the casing are stator windings through which current flows to create a magnetic field that rotates the permanent magnets, shaft and impeller. When the impeller is rotated, the coolant is passed through the housing and to the laser. The impeller also forces the fluid passing through the shaft and into the casing to cool and lubricate the pump. The magnets are encased in a titanium sleeve attached to the titanium shaft to prevent the coolant from contacting with the magnets.

Abstract: The invention presents a method and apparatus for utilizing a single frequency, self seeding laser pulse signal transmitted to create a target beam to be projected toward an atmospheric target whereby a portion will be reflected back upon itself, and a local oscillator beam constructed to a shape approximating a low level elongated square wave pulse to be heterodyned with the returning target beam. A radio frequency voltage drives an acousto-optic modulator and amplitude modulates the local oscillator beam to form an optical output that is a flat top pulse resembling a square wave function. The local oscillator beam and returning target beam are polarization adjusted to match and are then combined and focused onto detector. The system is effective for use as an aircraft velocimeter.

Abstract: A wavelength stabilization apparatus and method for a superfluorescent source comprising a SFS (superfluorescent source) comprising a fiber with a core doped with lazing material. The SFS source produces SFS light with an SFS wavelength when pumped with pump light from a pump light source having a pump light wavelength. An output controller responds to a sample of the SFS light and operates to maximize the power of the sample of SFS light by automatically adjusting the pump light wavelength. The output controller also has a pump power controller responsive to a sample of the pump light from the pump light source for stabilizing the output power of the sample of the pump light with respect to a predetermined reference output power level.

Abstract: A superfluorescent broadband fiber laser source comprises an optical fiber doped with a laser material and having one end pumped with pump light of sufficient intensity to produce amplified spontaneous emission within the fiber and forward and backward waves therefrom. The polarizations of the backward wave experiences a 45.degree. rotation as it travels into and another 45.degree. rotation as it passes back out of a 45.degree. Faraday rotator mirror device. An amplified polarization=rotated beam from the doped fiber is divided into orthogonally polarized beams in a polarization beam splitter coupler. A return polarized signal from an interferometer is passed through the doped fiber, the Faraday rotator mirror device and the doped fiber for producing a polarized output signal that has been amplified by four passes through the doped fiber.

Abstract: A calcium yttrium silicate oxyapatite laser crystal doped with thulium provides a laser material finding particular utility in 2 .mu.m diode pumped lasers. The calcium yttrium silicate oxyapatite doped with trivalent thulium, preferably has the formulaCa(Tm.sub.x Y.sub.1-x).sub.4 (SiO.sub.4).sub.3 O, where x=0.0025-0.12.

Abstract: An optical correlator system having a plurality of reflective optical components, both active and passive, positioned (1) between a source of electromagnetic radiation, such as a visible beam of coherent light, and an output detector array, and (2) around an asymmetrical perimeter of a planar support body to develop an asymmetrically folded optical axis or path wholly within the body where the path is traversed by the beam SO THAT information processed by the active optical components along the optical path and imparted to the optical beam enable the optical detection of an unknown object at the detector array which is then subject to an identification process.

Abstract: A mounting assembly for a night vision system is provided which allows the night vision system to be easily and rapidly switched from one eye to the next. The night vision system has an optical portion, and a control housing affixed to the optical portion. The control housing has a first and a second mounting plate. The mounting assembly has a first and a second carriage, and each of the carriages are configured to receive a selected one of the mounting plates. The mounting assembly can then be secured to either a face mask worn by the operator, or a helmet worn by the operator. The position of the carriages can be adjusted to compensate for the inter-pupillary distance and elevation relative a normal line of sight of an operator's eyes. The carriages are carried by a threaded rod having two portions threaded in opposite directions, so that rotation of the knob moves the carriages either closer together or further apart, as desired.

Abstract: An extended interaction output circuit interacts with a modulated electron beam and outputs RF electromagnetic energy. The circuit comprises a plurality of linearly disposed cavities each having a gap permitting the traveling therethrough of the modulated electron beam. A first pair of the linearly disposed cavities is coupled by a single side cavity, a second pair of the linearly disposed cavities is coupled by a pair of side cavities radially disposed 180 degrees apart, and a third pair of the linearly disposed cavities is coupled by three side cavities radially disposed 120 degrees apart. The linearly disposed cavities act as an RF filter having successively tapered impedances to reduce reflections of the electromagnetic energy propagating through the circuit. RF energy is extracted from the fourth cavity through four waveguide sections that are radially disposed 90 degrees apart.

Abstract: A split gain multi-mode ring laser gyroscope is disclosed having a radio frequency excitation induction coil which also serves the magnetic mode suppression system, suppressing undesirable modes of the gain curve to achieve the split gain effect. The induction coil serves as an important common component of both the gain medium excitation and mode suppression systems. The induction coil is suitably configured to carry both AC and DC signals.

Abstract: An injection seeded, single frequency ring laser source is presented wherein stabilization and single frequency control is accomplished by measuring the intensity or power of the portion of the high power laser beam generated in the ring slave laser and which is directed to return to the seed laser. When the intensity of the return beam falls below a preset threshold level, the in-phase operation of the laser system has been established and high energy single frequency pulses are generated and emitted.

Abstract: A laser apparatus or system is provided including a driving mechanism for driving a pulsed semiconductor laser which injects optical energy into a lasing medium. A digital filter is employed to adjust the time duration or pulse width of drive pulses which excite the semiconductor laser. In this manner, the irradiation of the lasing medium is adjusted by pulse width modulation of the driving current in the semiconductor laser. The laser apparatus employs a sampled output, digitally filtered, negative feedback signal to drive the semiconductor laser. This structure has the effect of making the semiconductor laser responsive to changes in the laser system or to undesired degradation in the laser system. The laser apparatus compensates for the inherent time lag in laser output power energy during initial startup of the laser.

Abstract: An optical transceiver is provided for transmitting a light pulse to a target and for receiving a reflected light pulse from the target. The transceiver includes a light source for transmitting a coherent light pulse which is reflected by the target along a first optical path as a reflected light pulse. The transceiver also includes a trigger signal generating circuit, coupled to the light source, for generating a trigger signal to indicate when the light pulse is transmitted. The transceiver further employs an attenuation device, responsive to the trigger signal and situated in the first optical path to intercept the reflected light pulse, for attenuating optical transmission through the first optical path inversely as a function of time from generation of the light pulse. In this manner, reflected light pulses reflected from targets close to the transceiver receive a greater amount of attenuation than reflected light pulses reflected from more distant targets.

Abstract: A clamp is connected to a base for retaining a reel in a predetermined position relative to the base. A pair of winding heads are mounted to the base so that the winding heads face each other with the reel retained between the winding heads. Each winding head includes a corresponding fiber supply spool. A coil of optical fiber is formed on the reel by alternately winding predetermined lengths of the fiber from each fiber supply spool onto the reel. The coil is formed by rotating the first winding head in a first direction relative to the reel to wind fiber from the first supply spool onto the reel while holding the second winding head stationary relative to the reel to prevent fiber from the second supply spool from being wound onto the reel while fiber from the first supply spool is being wound on the reel. The winding heads are moved in translational motion relative to the reel while the winding heads are rotated to wind the fiber in even layers on the reel.

Abstract: A fiber optic array having a plurality of subarrays of optical sensors, the subarrays being spaced apart along and optically connected to input and output buses through associated input and output optically actuated optical switches in series in the input and output buses. First and second light signal pulse trains are applied to one and other ends of the input bus and a third light signal pulse train is applied to one end of the output bus. The input switches are sequentially responsive to each first light signal pulse on the input bus for passing to an associated subarray a pulse of second light signal that is simultaneously present at that input switch such that second light signal pulses of the same magnitude are applied to each subarray. Associated output switches are sequentially responsive to third light signal pulses for passing trains of second light signal pulses from the arrays onto the output bus and to processing equipment.

Abstract: An optical system and method for rotating an image of an object is disclosed. The device consists of a plurality of optical surfaces for either reflecting or refracting the light along an optical path through the device. The optical surfaces divide the optical path into optical path segments which intersect at predetermined angles. These angles are selected to minimize polarization of the output light. The optical path segments lie in more than one plane.

Abstract: An improved resolution electron gun for a cathode ray tube(CRT) is provided having a cathode, a control grid and an anode. A positive voltage is applied to the anode for the purpose of drawing the electron beam from the cathod, which emits the electron beam along its principal axis. The control grid between the cathode and the anode has a modulating drive voltage to modulate the emitted beam. The anode and the grid are aligned along the principal axis of the cathode and are adjacent to one another. A limiting aperture is mounted along the principal axis to clip the beam and reduce its diameter. A screen is provided along the principal axis within the CRT to receive the projected beam. To obtain increased resolution, the modulating drive voltage is increased while the aperture size is decreased. More specifically, the modulating drive voltage is increased beyond 25% of a predetermined maximum cutoff value, and the limiting aperture permits less than 50% of beam current to transmit.

Abstract: A hybrid fiber optic transceiver is described which includes a transmitter for converting electrical data signals to corresponding light energy, a receiver for converting optical data signals back to electrical data signals and a clock recovery mechanism to maintain the electrical data signals outputs from the receiver in their proper order. The transceiver includes an optical splitter or coupler that allows light signals to be transmitted and received over a single fiber. The opto-electrical hybrid circuitry of the transceiver and the fiber optic coupler are enclosed in a small light weight package which is hermetically sealed.

Abstract: Optical fiber coils are formed on inner and outer mandrels. The inner mandrel is spaced apart from the outer mandrel to form a cavity between them with the inner fiber coil being inside the cavity. Water-tight seals between the inner and outer mandrels keep the inner coil isolated from underwater acoustic waves that may be incident upon the outer coil. The optical fibers are included in a dual optical path fiber optic interferometer that includes the inner fiber coil in a first optical path and the outer fiber coil in a second optical path. A central wall divides the inner region of the inner mandrel into two cavities. A tie rod has a first end connected to the wall and a second end extending out of the first cavity in the inner mandrel. A backshell is connected to the second end of the tie rod. The backshell includes a hollow portion formed as a housing for protecting fiber optic components of the interferometer.

Abstract: A phase modulation control apparatus is taught in combination with an interferometer excited by a coherent light source providing a light beam to the interferometer having first and second optical paths. The interferometer senses a physical quantity such as pressure. The interferometer is coupled to provide an optical signal containing information providing a measure of the physical quantity via first and second interfering beams to a detector. The detector provides a composite output signal. The invention phase modulation control apparatus has a modulation means responsive to a modulating frequency signal and a phase modulation control signal to provide a frequency modulating factor signal for frequency modulating at least a portion of the light beam to provide a phase modulation between the first and second interfering beams at a carrier frequency. The composite output signal has at least four harmonic signals referenced to the carrier frequency.