Frequency sensitive laser rotary motion sensor

Claim 2

A rotary motion sensor comprising the combination of: a closed polygonal optical loop; reference optical beam generating means; means for stimulating and maintaining bimodal coherent radiation circulating in said loop; means for coupling radiation in one mode only from said loop to said reference beam generating means; means responsive to the radiation coupled out of said loop for controlling the reference beam frequency at a frequency which differs from said one mode by a constant amount; means for coupling radiation in said other mOde out of said loop; means for comparing the characteristics of the reference beam and said other mode beam; and means for producing an output signal proportional to the difference between said reference beam and said other mode beam.

Claim 3

An apparatus according to claim 1 and further comprising: means in said loop for modulating said bimodal radiation to prevent mode locking.

Claim 4

An apparatus according to claim 2 wherein said means for producing an output signal includes: means in said means for producing an output signal for cancelling the modulation introduced to prevent mode locking.

Claim 5

An apparatus according to claim 1 wherein said means for stimulating radiation is a first laser; and said reference beam generating means includes a second laser.

Claim 6

An apparatus according to claim 4 wherein said reference beam generating means further includes a totally reflective end mirror for said second laser; and wherein said means for controlling the reference beam frequency includes means for adjustably supporting said end mirror in response to a control signal; and circuit means responsive to the reference beam and said one mode beam for developing said control signal.

Claim 7

In a rotary motion sensor of the type having a first closed optical path, laser means disposed in said path for producing radiation in both directions, the path including reflecting means for reflecting the radiation so that the radiation resonates in two modes, a second closed optical path, modulating means in the path for deflecting a portion of the radiation in each mode into the second path in accordance with a signal of predetermined frequency, a signal generator for generating a modulating signal of the predetermined frequency, circuit means for connecting the signal to the modulator and semireflective means for coupling radiation mode beams from both modes out of said second path, the improvement comprising: means for generating a reference optical beam at a controlled frequency; beam splitting means for dividing said reference beam into two components; first optical mixer means for accepting two optical beams and for producing an electrical signal representative of the frequency difference therebetween; means for directing one of said components and one mode beam from said second path to said first mixer means; second optical mixer means for accepting two optical beams and for producing an electrical signal representative of the frequency difference therebetween; means for directing the other of said reference beam components and the other mode beam from said second path to said second mixerm means; means for combining the modulating signal individually with the electrical signal outputs of said first and second optical mixer means to produce third and fourth signals; means responsive to said third signal for controlling the frequency of said reference beam at a constant frequency separation from one of said mode beams; and means for comparing the phase relationships of said third and fourth signals.

Claim 8

In a rotary motion sensor of the type having a first closed optical path, laser means disposed in said path for producing radiation in both directions, the path including reflecting means for reflecting the radiation so that the radiation resonates in two modes, a second closed optical path, modulating means in the path for deflecting a portion of the radiation in each mode into the second path in accordance with a signal of predetermined frequency, a signal generator for generating a modulating signal of the predetermined frequency, circuit means for connecting the signal to the modulator and semireflective means for coupling radiation mode beams from both modes out of said second path, the improvement comprising: means for generating a reference optical beam at a controlled frequency; beam splitting means for dividing said reference beam into two components; first optical mixer means for accepting two optical beams and for producing an electrical signal representative of the frequency difference therebetween; means for directing one of said components and one mode beam from said second path to said first mixer means; second optical mixer means for accepting two optical beams and for producing an electrical signal representative of the frequency difference therebetween; means for directing the other of said reference beam components and the other mode beam from said second path to said second mixerm means; means for combining the modulating signal individually with the electrical signal outputs of said first and second optical mixer means to produce third and fourth signals; means responsive to said third signal for controlling the frequency of said reference beam at a constant frequency separation from one of said mode beams; and means for comparing the phase relationships of said third and fourth signals.