Optics: measuring and testing – By light interference – Rotation rate
Reexamination Certificate
2006-05-02
2006-05-02
Lee, Hwa (Andrew) (Department: 2877)
Optics: measuring and testing
By light interference
Rotation rate
Reexamination Certificate
active
07038783
ABSTRACT:
A system for detecting the eigen frequency of a sensing coil in a fiber optic gyro (FOG) that includes a fiber coupler connected to the light source, an integrated optics chip (IOC) capable of modulating light received from the light source via the fiber coupler, a sensing coil in communication with the IOC, a first modulation generator for imparting a first modulation signal to the light, and a photodetector for receiving light returning from the sensing coil that is representative of a rotation rate of the sensing coil. Along with the foregoing there is provided a second modulation generator for imparting a second, preferably sinusoidal, modulation signal to the light, a high-frequency demodulator in communication with a signal produced, at least indirectly, by the photodector, and a low-frequency demodulator in communication with the high-frequency demodulator. The high-frequency demodulator receives the first modulation signal as a reference frequency and the low-frequency demodulator receives the second modulation signal as a reference frequency. An output of the low-frequency demodulator represents a magnitude and sign of a frequency difference between a frequency of the second modulation signal and an even-harmonic of the eigen frequency.
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Doheny David A.
Standjord Lee K.
Lee Hwa (Andrew)
Luther Kurt A.
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