Richard F Cahill, Age 71201 Windwood Ln, Sierra Madre, CA 91024

4789241, Dec 6, 1988

Feb 24, 1987

7/017691

Ronald J. Michal - Orange CA
Eric Udd - Huntington Beach CA
Richard F. Cahill - El Toro CA

McDonnell Douglas Corporation - Long Beach CA

G01B 902

356350

There is provided by this invention an optical sensing system utilizing a Sagnac interferometer having a frequency shifter within the Sagnac counterpropagating loop that is generally comprised of a plurality of acoustic transducers mounted on acousto-optical material to frequency shift and beamsplit a light beam simultaneously within the material while at the same time having the capability of switching between an upshifted or downshifted frequency in either a Bragg or Raman-Nath mode of operation without realigning the optical beams. The acousto-optical material has a special configuration to eliminate back reflections of the acoustic waves that can interact with the light beam. In addition, special alignment of the transducers with dampening configurations also serves to prevent back reflections of the acoustic wave from interacting with the light beam.

4787741, Nov 29, 1988

Oct 9, 1986

6/917390

Eric Udd - Huntington Beach CA
Ronald J. Michal - Orange CA
Steven F. Watanabe - Fountain Valley CA
John P. Theriault - Fountain Valley CA
Richard F. Cahill - El Toro CA

McDonnell Douglas Corporation - Long Beach CA

G01B 902

356 355

There is provided a fiber optic sensor for sensing environmental effects on counterpropagating light beams in an optical loop by comparing the modulation of the light beams in an optical coil exposed to the environmental effects and comparison with a reference fiber shielded from the environmental effects. The counterpropagating light paths contain optical phase modulators for creating nonreciprocal phase shifts and may comprise elongated sections forming a long line array.

4875775, Oct 24, 1989

Aug 20, 1984

6/642144

Ronald J. Michal - Orange CA
Eric Udd - Huntington Beach CA
Richard F. Cahill - El Toro CA

McDonnell Douglas Corporation - Long Beach CA

G01B 902
G01N 2141

356350

An optical instrument is provided which can be configured as a gyro, spectrometer, or other sensor of effects that can influence the transmission of light through a light conduit wherein a beam of light is split and introduced into both ends of an optical fiber which in the gyro case is a fiber-optic coil. Two fixed frequency shifters and two variable frequency shifters, one each at each end of the coil, which are switched on in alternate pairs, are used to adjust any nonreciprocal phase shift caused by rotation of the coil. The beams are mixed backed together and the resultant beam is detected and analyzed by suitable circuitry to provide an output indicative of the angular position, direction of rotation, and angular rate of the motion of the fiber-optic coil as well as any frequency bias and scale factor changes. When configured as a spectrometer, the coil is made insensitive to rotation so that changes are the result of changes in the light source.