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US 5,359,413 AGranted
System for substantially eleminating lock-in in a ring laser gyroscope
AssigneeKearfott Guidance & Navigation Corporation
InventorsTimothy H. Chang, Bo H. G. Ljung, Bernard Friedland
Life of this patent
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Abstract
A ring laser gyro system having at least one fixed mirror, and two movable mirror assemblies, for causing a pair of laser beams to counter-rotate therebetween, including amplitude control circuits and a phase control circuit for causing the movable mirror assemblies to sinusoidally oscillate at the same amplitude and frequency, but 180.degree. out of a phase with one-another, to substantially eliminate lock-in.
Claims21
A system for substantially eliminating lock-in in a ring laser gyroscope, said system comprising:
- a mounting block;
- at least one fixed mirror mounted within said mounting block;
- first and second movable mirror assemblies mounted within said mounting block, said first and second movable mirror assemblies each including a mirror and each being specially constructed to naturally oscillate at a common natural resonant frequency such that the mirrors of said first and second movable mirror assemblies both oscillate at said common natural resonant frequency, the combination of said at least one fixed mirror and the mirrors of said first and second movable mirror assemblies being arranged for reflecting laser beams therebetween, thereby establishing a beam path within said mounting block for two counter rotating laser beams;
- first and second amplitude control means corresponding to said first and second movable mirror assemblies, respectively, for controlling the amplitudes of oscillation of said first and second movable mirror assemblies so as to insure that the mirrors of said first and second movable mirror assemblies oscillate at said common natural resonant frequency at a predetermined amplitude of oscillation;
- and
- phase control means cross-coupled to said first and second amplitude control means, for controlling the phase relationship between said first and second movable mirror assemblies so as to insure that the mirrors of said first and second movable mirror assemblies oscillate at said common natural resonant frequency with a 180.degree. phase difference therebetween.
3 more elements
A system for substantially eliminating lock-in in a ring laser gyroscope during the operation thereof, said system comprising:
- a mounting block;
- first and second fixed mirrors;
- first and second movable mirror assemblies each including a mirror and each being specially constructed to naturally oscillate at a common natural resonant frequency such that the mirrors of said first and second movable mirror assemblies both oscillate at said common natural resonant frequency, said first and second fixed mirrors and the mirrors of said first and second movable mirror assemblies each being mounted within said mounting block relative to each other for reflecting laser beams therebetween so as to establish a beam path within said mounting block for two counter rotating laser beams;
- said first and second movable mirror assemblies each including drive means responsive to a drive signal for converting electrical energy into mechanical energy so as to perpetuate an oscillating motion in an associated mirror at said common natural resonant frequency, and pick-off means responsive to said oscillating motion of said associated mirror for converting mechanical energy into electrical energy so as to provide a pick-off signal proportional to the linear velocity of said oscillating motion of said associated mirror;
- first amplitude control means responsive to the pick-off signal from said first movable mirror assembly, for providing an amplitude component to the drive signal applied to said associated drive means for controlling the amplitude of oscillation of said first movable mirror assembly so as to insure that the mirror of said first movable mirror assembly oscillates at said common natural resonant frequency at a predetermined amplitude of oscillation;
- second amplitude control means responsive to the pick-off signal from said second movable mirror assembly, for providing an amplitude component to the drive signal applied to said associated drive means for controlling the amplitude of oscillation of said second movable mirror assembly so as to insure that the mirror of said second movable mirror assembly oscillates at said common natural resonant frequency at said predetermined amplitude of oscillation;
- phase control means responsive to the pick-off signals from said first and second movable mirror assemblies, for providing a phase component to the drive signals applied to the drive means associated with said first and second movable mirror assemblies, respectively, for controlling the phase relationship between said drive signals so as to insure that the mirrors of said first and second movable mirror assemblies oscillate at said common natural resonant frequency with a 180.degree. phase difference therebetween.
4 more elements
A method for substantially eliminating lock-in in a ring laser gyroscope including at least one fixed mirror and first and second movable mirror assemblies, said method comprising the steps of:
- constructing said first and second movable mirror assemblies to naturally oscillate at a common natural resonant frequency;
- arranging said at least one fixed mirror and said first and second movable mirror assemblies within a cavity relative to each other so as to allow laser beams to be reflected therebetween, thereby establishing a beam path within said cavity for two counter rotating laser beams;
- controlling the amplitudes of oscillation of said first and second movable mirror assemblies so as to insure that the mirrors of said first and second movable mirror assemblies oscillate at said common natural resonant frequency at a predetermined amplitude of oscillation;
- and
- controlling the phase relationship between said first and second movable mirror assemblies so as to insure that the mirrors of said first and second movable mirror assemblies oscillate at said common natural resonant frequency with a 180.degree. phase difference therebetween.
2 more elements
Dependencies are inferred from the claim text.