Steven J Gillespie

US Patent:

54424429, Aug 15, 1995

Filed:

Oct 28, 1987

Appl. No.:

7/114481

Inventors:

Edward Kanegsberg - Pacific Palisades CA
Steven C. Gillespie - Canoga Park CA
John P. Rahn - Canoga Park CA

Assignee:

Litton Systems, Inc. - Beverly Hills CA

International Classification:

G01B 802
H01S 3083

US Classification:

356350

Abstract:

The intensity and frequency variation due to retroscatter in a ring laser gyroscope are determined and used to correct the gyro scale factor. The orthogonal types of scatter due to dielectric variation and due to height variation, which lead to common mode phase delays of 0 and. pi. /2 respectively are taken into account in calculating the correction to the scale factor. The scale factor errors are determined in terms of observable quantities. Scale factor error control is accomplished by extracting a portion of both of the two counterpropagating light beams and measuring their respective intensities, creating intensity modulation indices representative of the sum and difference intensities, using closed loop control of the real-time difference between the intensities of the beam in the ring laser gyro to reduce scale factor variation using push-pull mirror control of at least two mirrors. The residual error after push-pull mirror control minimization is output for use by a navigation system computer.

US Patent:

47831693, Nov 8, 1988

Filed:

Aug 9, 1985

Appl. No.:

6/764441

Inventors:

Anthony Matthews - Calabasas CA
Guy T. Varty - Woodland Hills CA
Jeffrey S. Darling - Chatsworth CA
Steven C. Gillespie - Canoga Park CA

Assignee:

Litton Systems, Inc. - Beverly Hills CA

International Classification:

G02F 109
H01S 310

US Classification:

356350

Abstract:

A ring laser gyro having a cavity with at least one transducer-actuated mirror is controlled to conform to a preselected model of cavity operation. Control is accomplished by sampling cavity data, comparing the data to the model to generate an error signal, and controlling the mirror according to the error signal. In a preferred embodiment, at least two mirrors are dithered and the model defines an optimal amplitude of mirror dither at which theoretical lock-in error is zero. In another preferred embodiment, the sampled data corresponds to laser intensity within the cavity and the model defines an optimal intensity displaced from the maximum within an operating mode of the cavity. The model may define a plurality of operating modes of the cavity, ranked according to gyro performance for different values of a preselected environmental condition. The environmental condition is then sensed on an ongoing basis and used to select an optimal mode.