Abstract: A multi-phase coupler including a noise reduction circuit which provides two output signals which are separately shifted in phase with respect to an input radio frequency (RF) signal. The input RF signal is capacitively phase-shifted to lead the phase of an input RF signal to provide one output signal and is inductively phase-shifted to lag the phase of an input RF signal to provide a second output signal. The two phase-shifted outputs are impedance matched to the dual input ports of a balanced radiating structure that acts as a point source when the input ports are driven in phase quadrature.

Abstract: An active recognition system comprises a transceiver, tracking electronics, an optical processor, and a data handler. The transceiver transmits chirped pulses and receives a series of reflected ?replicas of the chirped pulse! replica pulses from ?features of! an object ?of interest!. The tracking electronics controls the transceiver to determine object range for gating the optical processor. The optical processor includes a "signal" Bragg cell driven by the reflection signal so that ?a! throughgoing light ?beam! is angularly redistributed as a function of the local spatial frequency of the acoustic waveform within the modulation aperture of the signal Bragg cell. At a first focal plane, the light defines a one-dimensional light distribution that includes moving spots that correspond to respective reflection replicas.

Abstract: An apparatus, using two acousto-optical tuned filters for determining the wavelength and angle of approach of a light wave.

Abstract: The invention temperature controlled package comprises a case having sidewalls that form a closed perimeter; a cover; and a base having an input surface and an output surface. The sidewalls are integrally coupled to the base input surface to define an interior region. A heatsink has a top surface and a bottom surface. The heatsink bottom surface is attached to the input surface of a thermoelectric cooler. The bottom surface of the thermoelectric cooler is coupled to the base input surface of the case. The thermoelectric cooler responds to a control signal to move heat from the thermoelectric cooler input surface to the thermoelectric cooler output surface. In a first alternative embodiment, a laser diode coupled to the heat sink responds to an electrical input signal to providing an optical laser output signal. The optical output of the laser diode is coupled via a optical fiber through a fiberoptic feedthrough in a sidewall. The interior region is filled with xenon gas.

Abstract: Apparatus and methods for reducing and preventing polarization fading in unbalanced measuring interferometers. An extended interferometer having a plurality of sensors and a compensating interferometer are used. They are driven from a pulsed optical signal source wherein the optical signal comprises sequences of two pulses each. To prevent polarization fading the polarization of a predetermined one of each two-pulse sequence is switched, preferably orthogonally, from sequence to sequence. Interference pulse output groups are produced for each two-pulse driving sequence. Each output group has the same number of usable pulses as the number of sensors in the interferometer.

Abstract: A protected fiber optical splice and a method for making the protected splice. The protective structure encapsulates first and second spliced optical fibers. The fibers are preferably fusion spliced. The protective structure includes a rigid tube surrounding the splice and its adjacent regions of the spliced fibers. A plastic such as an epoxy or moldable plastic is injected into the tube between the substantially axially centered fibers and splice, and the interior wall of the tube. Two molding fixtures are preferably surrounding the two ends of the tube, for injecting the moldable plastic into the tube and for shaping the portions of the structure external to the the tube ends.

Abstract: The use of a high speed moving average filter is shown to filter high speed errors, including white noise in angle and quantization errors, from the output data of a ring laser gyro while it is being tested. The filtered data permits investigation of the lower speed, random walk in angle error of the gyro being tested. For best results, several moving average filters are connected in series.

Abstract: A coupled cavity traveling wave tube is disclosed which includes a plurality of pole piece members and hollow spacer members which are alternately arrayed to define a plurality of cavities. The pole piece members each has a central aperture and a coupling slot through which microwave energy is coupled between adjacent cavities. The tube includes a plurality of first loss elements each of which is positioned in both of two respective adjacent cavities, with each of the first loss elements having its first end in contact with the front face of a respective one of the alternate pole piece members, its central portion pass through an aperture in the next intervening pole piece member in which it is coupled to the coupling slot in that pole piece member, and its second end in contact with the rear face of the next alternate pole piece member.

Abstract: A DC-to-DC Converter using four tightly coupled transformer windings, two energy transfer capacitors, and a pair of switching devices connected to remove the ripple from both the input and output current circuits. The switching devices are driven in response to a switching signal.

Abstract: A nonplanar ring laser for use as a laser gyro includes an even number of at least six reflecting surfaces which are preferably all made from the same coating batch or coating run so that they have substantially the same anisotropy characteristics. The mirrors are divided into pairs of mirrors, and the mirrors in at least each pair must match in their anisotropic characteristics. Note that the matched mirrors need only be in the laser path but not necessarily adjacent.The nonplanar geometric arrangement of the reflecting surfaces is such that the reflecting plane of incidence of each mirror is at substantially a right angle to the reflecting plane of incidence of at least one of the adjacent mirrors in the laser path. Note that the reflecting plane of incidence of each mirror may optionally be at right angles to the reflecting planes of incidence of both its adjacent mirrors in the laser path.The angles of incidence of the mirrors in each matched pair must be substantially the same.

Abstract: A terminal unit having a digital autostart circuit for energizing an output device such as a teleprinter. The autostart circuit responds only to the space character which is transmitted between every word in the commonly used Murray and ASCII codes. A method for detecting the presence of information signals encoded in the Murray and ASCII codes wherein a predetermined bit of each incoming signal is inverted and the binary states of each bit of incoming character are sensed to determine the presence of the space character.

Abstract: Apparatus for chopping DC power at a high frequency, for example 20 kHz, such high frequency being pulse-width modulated by a lower power frequency source at the desired power frequency. The pulse width modulation is servo controlled through current and voltage feedback to cause the current delivered to a load impedance to be in phase with a reference to power frequency oscillator and to control the output frequency voltage amplitude.

Abstract: A ring laser gyroscope system is provided in which four frequencies of oscillation are allowed to simultaneously propagate within the ring laser cavity, with two modes propagating in each direction. Separation of the resonant frequencies is accomplished through reciprocal, nonreciprocal, and anisotropic optical effects within the laser path, plus Zeeman effect produced by a magnetic field in a predetermined intensity range over the laser gain plasma. The magnetic field substantially parallel to the laser path over the gain medium reduces the effects of hole burning or source depletion when the amplitudes of the field is within a predetermined intensity range to allow frequencies of the four modes to be spaced closer together. The system employs cavity length control circuitry to optimize system output. Rotation of the system results in frequency changes which are detected and processed to yield inertial rotation information.

Abstract: A redundant inertial reference system is provided with four gyroscope units, with the spin axes of the gyroscopes in the units being oriented, respectively, perpendicular to the four faces of an equilateral tetrahedron. Incidentally, a tetrahedron is a four sided body, and an equilateral tetrahedron is a four sided body having equilateral triangles for the four sides. With the four gyroscopes mounted perpendicular to the four sides of an equilateral tetrahedron, each of the gyroscopes is located symmetrically with respect to the others, with an angle of approximately 109.4 degrees between the spin axes of the gyroscopes. The system is particularly applicable to strapdown type inertial guidance systems and can provide three dimensional orientation information even if two of the gyros fail. The system uses four gyro units, a minimum number which can accomplish a foregoing function, with the four gyro units arranged substantially symmetrically with respect to one another.

Abstract: A system for determining orientation or position of a movable supporting structure, such as a vehicle, includes a special inertial sensor unit. This unit includes a single gyroscope hereinafter referred to as a "gyro", with its spin axis mounted in alignment with the sensitive axis of an accelerometer. The gyro and accelerometer are mounted pendulously to rotate only about a single axis which is aligned with a direction of travel of the vehicle or with a projectile launching assembly. In additon to being pendulously mounted as mentioned above, the gyro and accelerometer combination may be rotated relative to their pendulous support, to certain fixed positions, in order to facilitate rapid initial alignment and orientation and pre-mission calibration of the inertial instruments. The pendulously mounted unit is also provided with an optical encoder to indicate the roll angle of the vehicle to which the inertial unit is secured.

Abstract: A nuclear magnetic resonance gyroscope is disclosed that operates on the principle of sensing angular rotation rate as a shift in the Larmor frequency of one or more nuclear species that possess nuclear magnetic moments.

Abstract: Three electrically isolated photosensitive diodes on a common substrate are located directly behind a multilayer dielectric coated mirror that is one of the reflective elements of a ring laser. A small percentage of the beams incident on the mirror is allowed to pass through and strike the photosensitive diodes. Two of the diodes are masked in such a way as to detect the heterodyne beat signal of two counterrotating beams in the ring laser and generate an output signal used to determine rate of rotation of the ring laser body. The third diode sums the intensity of the counterrotating beams and generates an output signal which goes to a feedback cavity length control circuit.

Abstract: A flexure hinge assembly comprising a pair of fixed telescopes inner and outer tubular members separated into at least one driving portion, at least one gimbal portion and at least one driven portion and a plurality of flexure blades all formed by a plurality of slots and apertures through the walls of each tubular member. Flexure blades are formed by pairs of adjacent apertures with the slots interconnecting apertures to separate the tubular members into the driving, gimbal, and driven portions. A pair of diametrically opposed flexure hinges, each comprising two mutually orthogonal flexure blades one in the outer and one in the inner member, connect each gimbal portion to the driving portion. Another such pair of flexure hinges connect each gimbal portion to the driven portion.

Abstract: A method for fabricating multiple layer interference optical films by ion beam sputtering, said films being used for mirrors in a ring laser apparatus. An ion beam strikes a target material obliquely, dislodging molecules of the target so that they can be deposited on a surface serving as a base for a multiple layer interference coating. The thickness of the coating is monitored so that the proper thickness of a given layer can be optimized to obtain the type of reflectance desired for a given light wave length. The surface to be coated is rotated during the deposition of the layer of target material. A stack of layers of alternating indices of refraction comprises the optical interference film. The coating process occurs inside of a vacuum chamber where the partial pressures of the gases are carefully controlled to insure the proper ion beam intensity and optimum stoichiometry of the deposited optical films.

Abstract: A flexure hinge assembly comprising a pair of fixed telescopes inner and outer tubular members separated into at least one driving portion, at least one gimbal portion and at least one driven portion and a plurality of flexure blades all formed by a plurality of slots and apertures through the walls of each tubular member. Flexure blades are formed by pairs of adjacent apertures with the slots interconnecting apertures to separate the tubular members into the driving, gimbal, and driven portions. The four slots of each tubular member which divide that member into these three portions are axially coextensive with the slots in the other member and all extend in the same axial direction from the apertures which form the flexure blades. Such axially coextensive slots displace the driving and the driven portions of the tubular members in the same axial direction from the center of suspension, i.e., from the flexure axes of these portions.