The Charles Stark Draper Laboratory, Inc.

Raymond Carroll

Marc Steven Weinberg

Byong-Ho Ahn

William M Johnson

Michele S Sapuppo

Bruce Porter

Kenneth Fertig

Howard L Watson

A passive resonator gyroscope in which a laser beam is split into two equal intensity beams in a waveguide, each of the beams being coupled to counterpropagate around a fiber optic ring. The beams, after splitting, are frequency modulated with a voltage having a serrodyne waveform, the polarity of the voltage applied to the modulator for the one beam being opposite to the polarity of the modulating voltage applied to the modulator for other beam. The laser frequency is locked to the optical cavity half wave resonant frequency and when the laser is so locked, the modulating voltage is applied for a first period with one polarity and then for a second period of the same duration with the opposite polarity. The output beams from the optical fiber ring are combined in the waveguide and a portion of the combined optical beam is provided to a photodetector. A circuit connected to the photodetector determines the difference between the light impinging upon the photodetector during the first period and during the second period, this difference providing a measure of the Sagnac shift produced by the rotation of the fiber optic ring.

Resonant interferometer fiber optic gyroscope

An axial gyroscopic pointing reference for mounting on optics within an internally cooled telescope a resonant fiber optic gyroscope, in which the elements of the fiber optic gyroscope are cryogenically cooled with the same system that cryogenically cools the telescope optical elements. In one specific configuration the pointing reference includes three orthogonally positioned resonant fiber optic gyroscopes supported in a tetrahedron configuration and cryogenically cooled by the telescope cooling system.

Ultraminiature tactical grade cryogenic RFOG

A high-energy laser system having gyroscopically stabilized optical elements includes an unstable confocal laser resonator having first and second spinning cavity feedback mirrors that resist mechanical wave energy induced spatial dislocations by gyroscopic inertia. One or both of the spinning cavity mirrors are preferably mounted for rotation with the rotor of a gyroscope. The gyroscope is operative as an actuator for selectively tilting the spinning mirror, and as a direction indicator for controlling the pointing direction of other elements with respect to inertial space. The angular rotation of the cavity feedback mirrors generates aerodynamic flows that cool the spinning mirrors by convective heat transport. Every material particle thereof describes an annular path once per revolution that prevents hot-spot formation and extends the useful lifetime.

High-energy laser system having gyroscopically stabilized optical

A system for electronically tuning and suppressing 2N rectification torques in a dynamically tuned free rotor gyroscope with a universal hinge, or a plurality of universal hinges. The system includes means to adjust the frequency of the drive shaft of the gyroscope to a speed such that the rotor precession due to direct elastic restraint torques is eliminated. In addition, the system includes means for measuring the two degree of freedom angular deviations of the principal axis of the rotor with respect to the gyroscope case, as well as the angular deviations of the shaft spin axis relative to the gyroscope case. The sensed angular deviations of both the rotor and shaft drive a torque generator which produces a torque on the rotor for nulling torque due to angular vibrations of the drive shaft with respect to the rotor. The controlled phasing and gain of the nulling torque provides both average bending compliance tuning and suppression of the 2N rectification.

System for electronically tuning and suppressing 2N rectification

A single vibration sensor having the capability of sensing vibration along three rotational axes as well as three translational axes and exhibiting consistent dynamics over a wide frequency range. The sensor includes an elongated mass formed of a generally rigid material suspended in a fluid within a housing. The exterior surface of the mass is spaced from the interior surface of the housing to permit limited freedom of motion of the mass within the housing. The mass is provided with multiaxial radial and axial electromagnetic suspensions, and is typically supported by a fluid within the housing. Rotational positioning is provided by a signal generator, torque generator combination. Vibration is sensed by additive or differential measurements of current changes in the coils of different axes of the suspensions or electromagnetic signal and torque generator combinations. The sensor is conveniently implemented as a single degree of freedom inertial gyroscope without the gyroscope wheel and adapted to permit sensing of current changes in coils provided to achieve suspension or suspension and signal and torque generation functions.

Growing community of inventors

Andover, MA, United States of America

Raymond Carroll