Patent ID: 7933020

Claim:
A resonator gyroscope comprising: a reference laser generator, the reference laser generator comprising: a master light source to produce a reference light; a frequency discriminator to linearly convert frequency fluctuations of the reference light to intensity fluctuations; a photodetector to convert fluctuations in the intensity of an optical output of the frequency discriminator to an electrical voltage; a differential amplifier to compare the output voltage of the photodetector with a stable reference voltage; and servo electronics to provide control signals to the master light source to lock the master light source to a frequency in the linear portion of the resonance curve such that frequency fluctuations are converted linearly to intensity fluctuations, the control signals also driving the master light source such that low-frequency fluctuations in the reference light are removed; a first slave light source having a first modulation frequency to produce a first slave light having a first frequency; a first phase-lock-loop (PLL) to beat the first slave light with the reference light and to drive the first slave light source such that the first slave light is locked to the reference light; a second slave light source having a second modulation frequency to produce a first slave light having a second frequency; a second phase-lock-loop (PLL) to beat the second slave light with the reference light and to drive the second slave light source such that the second slave light is locked to the reference light; a resonator coupled to said first and second light sources, the resonator having first and second counter-propagating directions and comprising an optical fiber coil, wherein the resonator circulates a first circulating light through the optical fiber coil in the first counter-propagating direction, the first circulating light based on a portion of the first slave light; and circulates a second circulating light through the optical fiber coil in a second counter-propagating direction, the second circulating light based on a portion of the second slave light; and resonance tracking electronics coupled to the resonator to generate a first beat frequency based on a first resonance frequency for the first counter-propagating direction, a second beat frequency based on a second resonance frequency for the second counter-propagating direction, and a third beat frequency based on a third resonance frequency for the second counter-propagating direction; wherein the second resonance frequency is at least one resonance mode lower than the first resonance frequency and the third resonance frequency is at least one resonance mode higher than the first resonance frequency and the rotational rate of the resonator gyroscope is a function of the first, second and third beat frequencies.