Litton Systems, Inc.

Robert A Mitchell

David Barnett Hall

Christine E Geosling

Tae W Hahn

Ralph A Patterson

Stuart A Mills

Carl Bathelt, Jr

Kenneth W Shafer

Shane Sammon

James Ryan

A ring laser gyroscope includes a first plasma shunt arranged to prevent the plasma from contacting a first mirror in the gain region and a second plasma shunt arranged to prevent the plasma from contacting a second mirror in the gain region. The first and second plasma shunts may comprise electrical conductors located in the respective mirror wells and arranged such that contact between the plasma and the electrical conductors quenches the plasma in the mirror wells and produces electrical currents that travels across the mirror wells. The electrical conductors may be formed as metallized strips arranged to extend across the mirror wells, or they may be formed from metal wires. The plasma shunts may alternatively comprise diversion passages formed in the frame and arranged such that the plasma fills the diversion passages and bypasses the mirrors.

Plasma shunting apparatus and method for ring laser gyroscope

An apparatus and method is provided for facilitating ionization of a gas medium of a laser gyroscope. The apparatus and method employ a solid state light emitting device as a start aid for the laser gyroscope. The solid state light emitting device has a wavelength at or below a threshold wavelength based on a work function of a cathode coating material to prompt ionization of a gas medium within the laser gyroscope.

Apparatus and method to facilitate laser gyroscope ionization

An improved optical correlator using a coherent light beam employs a method of adaptive alignment. A test pattern modulates an input spatial light modulator. The modulated beam propagates through passive transforming optical elements to a filter spatial light modulator, which is simultaneously modulated with an independently transformed frequency domain reference. The resulting correlation or coincidence of the optically transformed pattern with the independently transformed reference is processed to yield a feedback signal indicative of any optical misalignment of the optical correlator. The feedback signal drives a beam deflector to compensate by adjusting the path of the coherent beam, thereby improving and maintaining optical alignment of the correlator.

Adaptively aligned optical correlator and method

Based upon the equation, BIAS.sub.G .alpha. (I.sub.DE -I.sub.COIL).multidot.(V.sub.DE -V.sub.OFF), where BIAS.sub.G is the bias of a multi-oscillator ring-laser gyroscope (14) as induced by gain medium dispersion effects, I.sub.DE is the proper operating coil current, I.sub.COIL is the actual coil current, V.sub.DE is the proper path length control operating voltage and V.sub.OFF is the actual offset voltage, V.sub.DE is matched by path length control offset voltage and/or I.sub.DE is matched by proper coil current, to produce a zero induced BIAS.sub.G. Matching, through dispersion equalization (DE), is effected by use of clockwise (C) and anticlockwise (A) (or counterclockwise) beams traversing paths with a frame (12). The beams are directed to photodetectors (52, 54) and power meters (56, 58).

Means and method for active dispersion equalization of a multioscillator

At least one coil (32) is located on an exterior side face (30) of a frame (12) of a ring laser gyroscope (10) such that a significant component of the magnetic field generated by the coil is colinear with the plasma discharge of the gyroscope, and by which dispersion equalization of the gyroscope can be effected. The coil may be supported by a magnetically permeable annular bobbin (40), which is set about a mirror (26) on side face (30) and which may be partly set within grooves in the side face, to reduce the current necessary to effect dispersion equalization and to provide shielding of the mirror from the effects of tangential and transverse fields, and to increase the shielding effects for the mirror, both from Faraday rotator magnets (16) and from external magnetic fields. For those mirrors where no coils are present, the annular bobbins are used solely for their shielding properties.

Simplified dispersion equalization field coil design for a

A ring laser gyroscope output optics detection system, including a rotational sensing system and cavity length control system for a multioscillator ring laser gyroscope, is disclosed herein that can operate with a simple upright symmetric optics mechanism, where the required signal separation is performed fully electronically. In a preferred embodiment, signal separation circuitry is provided which performs a 90.degree. or .pi./2 radians phase shift to one of a set of heterodyned signals in order to extract the sagnac effect modulated Faraday frequency signals W.sub.A and W.sub.B. In order to deal with the inherent problems of crosstalk present in a Faraday biased system, alternative signal separation schemes suggest the use of a 45.degree. or .pi./4 radians phase shift, as well as a 60.degree. or .pi./3 radians phase shift. Complementary cavity length control schemes are presented in both fixed component and digitally controlled formats.

Growing community of inventors

Woodland Hills, CA, United States of America

Robert A Mitchell