US 6,546,798 B1Granted

Micro-electro-mechanical systems resonant optical gyroscope

AssigneeThe United States of America as represented by the Secretary of the Navy

InventorsRichard L. Waters, Monti E. Aklufi

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Abstract

A gyroscope is based upon the integration of an optical resonant cavity and a photodiode to detect minute perturbations due to angular forces. A Fabry-Perot cavity is created from two parallel semitransparent mirrors used in conjunction with a monochromatic light source. One mirror is fixed while the other is allowed to rotate with respect to the first mirror. A resonant cavity is thereby formed on either side of the axis. The gap between the mirrors is set so that light transmission through the mirrors is optimized. Rotation of the mirror from this position causes the distance between the mirrors to be altered and the light transmission on either side of the rotational axis to be change. Photodiodes on these sides sense this change as a change in photo-generated current, enabling the amount of change in rotation to be calculated. The photo-currents can be differentially amplified for sensitivity.

Claims28

Dependent claims

A high sensitivity micro-electro-mechanical optical gyroscope comprising:

an interferometer section, including a pair of partially transmissive, partially reflective, surfaces wherein a first of said surfaces is disposed to rotate with respect to a second of said surfaces about an axis that is spaced apart from and parallel to said second surface so that an even gap exists between said surfaces when said surfaces are parallel, said first surface having first and second portions extending radially oppositely from said axis;
a proof mass attached to said rotatably disposed first surface;
a source of monochromatic light, said light for irradiating through said first and second surfaces wherein said light is also partially reflected between said surfaces;
a first photosensor for sensing said light as projected through said first portion of said first surface and said second surface;
and
a second photosensor for sensing said light as projected through said second portion of said first surface and through said second surface,
wherein said gap is set so that rotational forces as sensed by said gyroscope cause said first surface to rotate with respect to said second surface thereby either initially increasing light transmission through said first surface's first portion and said second surface and decreasing light transmission through said first surface's second portion and said second surface or initially decreasing light transmission through said first surface's first portion and said second surface and increasing light transmission through said first surface's second portion and said second surface.

4 more elements

A high sensitivity micro-electromechanical optical gyroscope comprising:

an interferometer section, including a pair of partially transmissive, partially reflective, surfaces wherein a first of said surfaces is disposed to rotate with respect to a second of said surfaces about an axis that is spaced apart from and parallel to said second surface so that an even gap exists between said surfaces when said surfaces are parallel, said first surface having first and second portions extending radially oppositely from said axis, said interferometer section including first and second Fabry-Perot interferometers, wherein an etalon of said first Fabry-Perot interferometer includes said first portion of said first surface and said second surface and wherein an etalon of said second Fabry-Perot interferometer includes said second portion of said first surface and said second surface;
a proof mass attached to said rotatably disposed first surface;
a source of monochromatic light, said light for irradiating through said first and second surfaces wherein said light is also partially reflected between said surfaces;
a first photodiode attached to said second surface outside of said gap for sensing said light as projected through said etalon of said first Fabry-Perot interferometer;
and
a second photodiode attached to said second surface outside of said gap for sensing said light as projected through said second Fabry-Perot interferometer,
wherein said gap is set so that rotational forces as sensed by said gyroscope cause said first surface to rotate with respect to said second surface thereby either initially increasing light transmission through said etalon of said first Fabry-Perot interferometer and decreasing light transmission through said etalon of said second Fabry-Perot interferometer or initially decreasing light transmission through said etalon of said first Fabry-Perot interferometer and increasing light transmission through said etalon of said second Fabry-Perot interferometer.

4 more elements

Dependencies are inferred from the claim text.