Litton Systems, Inc.

Other

Thomas J Hutchings

Virgil E Sanders

Gary D Babcock

David C Grant, Jr

George A Pavlath

Graham J Martin

John P Rahn

Nicholas Koumvakalis

Leo K Lam

Salim N Jabr

Edward Kanegsberg

Tae W Hahn

Sheridan W Hammons

Daryl C Stjern, Deceased

Edmund W Rusche, Legal Representative

An electro-optic device is used to detect the position and speed of a golf club head as it passes in front of the device. This information triggers a short optical pulse of light to illuminate the club head, allowing a golfer to see the club head at a desired position as an after-image, and to read the displayed club head speed.

Golf swing trainer

Disclosed herein is an External Scatter Removal System for Ring Laser Gyroscopes (such as a Split Gain Multioscillator) comprising a prism mounted on an optoisolator, wherein light transmitted out at least one of the mirrors of the Gyroscope passes into the prism and detector system, while oppositely directed backscattered light from the prism components is not returned to the gyroscope frame's internal optical path, thereby limiting any appreciable backscatter from interfering with an accurate measurement of the rotation rate of the gyroscope.

External scatter removal system

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.

Path length controller with offset bias for a ring laser gyro

Phase errors that occur when a dithered ring laser gyroscope enters its deadband are measured, and a correction is applied to the output of the ring laser gyroscope to compensate for these phase errors. The counterpropagating beams in a ring laser gyroscope are heterodyned to produce a pair of quadrature heterodyne signals that indicate the angular output of the laser ring laser gyroscope. The phase angle error between one of the heterodyne signals and either the sum or difference of the separate beam intensities is determined, The phase angle error signal is used to produce a control signal for adjusting the output of the ring laser gyroscope to correct for errors introduced at or near turnarounds in the dither cycle.

Apparatus and method for correcting ring laser gyroscope phase angle

A method and system of ring laser gyroscope mirror orientation is disclosed which provides minimal backscatter within the closed optical pathway as a result of analysis and manipulation of the speckle pattern associated with each of the mirrors defining the optical pathway.

Ring laser gyroscope mirror orientation system and method

A compact three axis ring laser gyroscope having six laser corner mirrors which are positioned on the faces of a parallelopiped laser block, and method for making. Preferably the laser block is a cube. The laser block has a plurality of conduits therein for defining a plurality of closed laser beam-paths for guiding counterpropagating laser waves. Each laser beam-path has a gain medium therein and is formed to define a sensing axis for detection of rotations of the laser block. A single cathode is positioned inside the laser block, preferably substantially at its geometric center, and a plurality of anodes are mounted to the laser block and spaced apart from the cathode. A ion flow path is formed between each anode and the cathode such that application of a suitable electrical potential difference between the anodes and the cathode produces counterpropagating laser beams in each laser beam-path. The anodes are arranged to eliminate undesired Fresnel-Fizeau phase shifts by ensuring that each of the three ring gyros has two opposing ion flows.

Common mirror triaxial ring laser gyroscope having a single internal

Apparatus for producing a three phase signal from two or three optical beams at different optical frequencies, such signal having a frequency equal to the difference frequency or frequencies between the optical frequencies of said beams including, preferably, an equal energy single mode fiber optic coupler and optical focusing means, such as gradient index rods, for directing said light beams onto light conducting fibers, preferably single mode fibers, thence through the coupler, thence onto light detectors to produce a substantially balanced three phase electrical signal at said difference frequency or frequencies. In a preferred embodiment, the light beams are two in number, connected to only two input ports of said coupler, and the light beam sources are the output beams of counter- propagating ring laser beams in a ring laser gyro.

Fiber optical combiner particularly for a ring laser gyro

Apparatus for maintaining the length of a ring laser path and of its branches substantially constant during temperature and stress changes, using forcers directed outward toward the apexes of the ring laser and perpendicular to the laser path.

Path length adjuster for ring laser gyro

A Zeeman ring laser gyro is described which includes a laser medium of helium-neon consisting of dual isotopes of Ne.sup.20 and Ne.sup.22 in which 53.5% is Ne.sup.20 and 46.5% is Ne.sup.22 by volume. The laser also includes a reciprocal anisotropic dispersion element of quartz which optically splits right and left circularly polarized laser waves by 250 MHz. The portion of the laser cavity in which laser emission is stimulated is exposed to a colinear magnetic field of 30.sub.-20.sup.+10 gauss. The combined optimum parameters produce a laser gyro insensitive to changes in detuning frequencies and magnetic fields.

Zeeman multioscillator ring laser gyro insensitive to magnetic fields

A dithered ring laser particularly adapted for use as a gyro wherein backscatter from the mirrors is minimized by servoing the mirror inward and outward positions so that the sum of the AM amplitudes of the envelopes of the counterpropagating waves is reduced to a minimum value, then further servoing the mirrors to reduce the difference between such AM amplitudes.

Ring laser

A mirror constrained to translation and whose position is controlled by a piezoelectric ceramic operating as a bimorph.

Controllable mirrors

A ring laser wherein, in the preferred embodiment, the laser path is substantially square, and the path length is adjustable by making at least one of the mirrors slightly tilted and one of the mirrors concave with at least the concave mirror translatable.

A single mode laser gyro having two oppositely traveling laser beams is provided with mechanically dithered mirrors at its three or four reflection points. Each mirror is mounted for movement in and out as the result of the expansion and contraction of stacks of piezoelectric elements associated with each mirror. The mirrors are dithered or oscillated in and out, at the same frequency and in phase relationship with one another so that the perimeter distance for the laser cavity is held at a fixed number of wavelengths, but the laser beam translates back and forth across the faces of the mirrors. By this technique, the undesired phenomena of lock-in at low rotation rates is avoided, without the need for special optical or magnetic structures in the path of the laser beam.

Laser gyro with phased dithered mirrors

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.

Photosensitive diodes for simplified optical heterodyning and cavity

A compact and reliable dithered laser gyro utilizes a rectangular laser path geometry to reduce scattering and thereby improve anti-locking capabilities of the laser gyro. In addition, the rectangular geometry serves to reduce the overall package size of the laser gyro and permits the mounting of the anti-lock mechanical dithering drive mechanism within the laser gyro unit. A counterbalance is also provided to reduce vibration from the unit.

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Thousand Oaks, CA, United States of America

Thomas J Hutchings