US 8,213,019 B2Granted

RFOG with optical heterodyning for optical signal discrimination

AssigneeHoneywell International Inc.

InventorsLee K. Strandjord, Glen A. Sanders, Tiequn Qiu

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Abstract

A RFOG comprises a reference laser configured to produce a reference laser beam; a first laser source configured to produce a first laser beam; a second laser source configured to produce a second laser beam; a sensing resonator coupled to the first and second laser sources such that the first and second laser beams propagate through the sensing resonator in first and second directions, respectively; resonance tracking electronics configured to generate first and second control signals that indicate when the first and second laser beams, respectively, are off resonance; first and second optical combiners configured to beat the first and second outputs of the sensing resonator with the reference laser beam creating first and second beat signals, respectively; wherein the resonance tracking electronics is configured to discriminate between at least one rotation-sensing error and the first and second outputs of the resonator based on the first and second beat signals.

Claims20

Dependent claims

A resonator fiber-optic gyro (RFOG) comprising:

a reference laser configured to produce a reference laser beam having a reference frequency;
a first laser source configured to produce a first laser beam having a first frequency offset from the reference laser beam;
a second laser source configured to produce a second laser beam having a second frequency offset from the reference laser beam;
a sensing resonator having a first input coupled to the first laser source and a second input coupled to the second laser source such that the first laser beam propagates through the sensing resonator in a first direction and exits at a first output and the second laser beam propagates through the sensing resonator in a second direction and exits at a second output;
resonance tracking electronics configured to generate a first control signal that indicates when the first laser beam is off resonance and to generate a second control signal that indicates when the second laser beam is off resonance;
a first optical combiner coupled between a first output of the sensing resonator and a first input of the resonance tracking electronics, the first optical combiner configured to beat the first output of the sensing resonator with the reference laser beam creating a first beat signal;
wherein the resonance tracking electronics is configured to discriminate between the first output of the resonator and at least one rotation-sensing error based on the first beat signal;
and
a second optical combiner coupled between a second output of the sensing resonator and a second input of the resonance tracking electronics, the second optical combiner configured to beat the second output of the sensing resonator with the reference laser beam creating a second beat signal;
wherein the resonance tracking electronics is configured to discriminate between the second output of the resonator and at least one rotation-sensing error based on the second beat signal.

7 more elements

A system comprising:

a resonator fiber-optic gyroscope configured to measure rotation rate;
and
a processing unit coupled to the resonator fiber-optic gyroscope and configured to perform calculations based on the rotation rate measured by the resonator fiber-optic gyroscope;
wherein the resonator fiber-optic gyroscope includes:
a sensing resonator have a first resonance frequency for a first laser beam propagation direction and a second resonance frequency for a second laser beam propagation direction;
an optical mixer coupled to an output of the sensing resonator and configured to mix an output of the sensing resonator with a reference laser, wherein the optical mixer outputs a beat signal;
and
a resonance tracking electronics coupled to the optical mixer and configured to demodulate the beat signal at a frequency offset to produce a first demodulated signal;
the resonance tracking electronics further configured to demodulate the first demodulated signal at a resonance tracking modulation frequency.

6 more elements

Dependencies are inferred from the claim text.