Readout for a ring laser angular rate sensor
AssigneeHoneywell Inc.
InventorsJames W. Bergstrom, Mark W. Weber
Life of this patent
Estimating the term…
Abstract
A pair of photodetector output signals are positioned so as to be responsive to the interference pattern produced by the pair of laser beams of the ring laser. The photodetectors are positioned such that the output signals are in phase quadrature. A second pair of signals is derived from the first pair of signals in which the second pair are displaced in phase relative to the first pair and are also in phase quadrature. The two pairs of signals are signal processed to enhance resolution of the ring laser readout.
Claims10
A readout apparatus for a laser angular rate sensor having counter-propagating laser beams which exhibit a change in frequency dependent upon rotation rate and direction, said readout apparatus comprising:
- means for optically combining a portion of each of said beams to form an interference fringe pattern;
- photodetection means responsive to said interference fringe pattern for providing a first pair of equal amplitude first and second signals substantially in phase quadrature and indicative of said interference fringe pattern impinging on said photodetection means;
- means for summing said first and second signals and providing a third signal indicative of said sum;
- means for determining the difference between said first and second signals and providing a fourth signal indicative of said difference;
- and
- signal processing means responsive to said frist, second, third, and fourth signals for generating a readout output signal having a signal change for substantially each 1/8 of a fringe change passing said photodetector means.
A readout apparatus for a laser angular rate sensor having counter-propagating laser beams which exhibit a change in frequency dependent upon rotation rate and direction, said readout apparatus comprising:
- means for optically combining a portion of each of said beams to form an interference fringe pattern;
- photodetection means responsive to said interference fringe pattern for providing a first pair of first and second analog signals substantially in phase quadrature and indicative fo said interference fringe pattern impinging on said photodetection means;
- means responsive to said first pair of signals for providing a second pair of third and fourth analog signals in phase quadrature and phase displaced by a selected phase angle value relative to said first pair of signals;
- and
- output means responsive to said first and second pairs of analog signals for providing an output signal change corresponding to selected zero crossings of said first and second analog signal pairs.
A readout apparatus for a laser angular rate sensor having counter-propagating laser beams which exhibit a change in frequency dependent upon rotation rate and direction, said readout apparatus comprising:
- means for optically combining a portion of each of said beams to form an interference fringe pattern;
- photodetection means responsive to said interference fringe pattern for providing a first pair of first and second signals substantially in phase quadrature and indicative of said interference fringe pattern impinging on said photodetection means;
- means for vectorially combining the weighted sum of said first and second signals to provide a third signal displaced in phase by a selected phase value relative to said first signal of said first pair;
- means for vectorially combining the weighted sum of said first and second signals to provide a fourth signal in phase quadrature with said third signal;
- and
- signal processing means responsive to said first, second, third, and fourth signals for generating a readout output signal having a signal change for substantially each zero crossing of said first, second, third, and fourth signals.
Dependencies are inferred from the claim text.