Laser gyro with phased dithered mirrors
AssigneeLitton Systems, Inc.
InventorThomas J. Hutchings
Life of this patent
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Abstract
A single mode laser gyro having two oppositely traveling laser beams is provided with mechanically dithered mirrors at its three or four reflection points. Each mirror is mounted for movement in and out as the result of the expansion and contraction of stacks of piezoelectric elements associated with each mirror. The mirrors are dithered or oscillated in and out, at the same frequency and in phase relationship with one another so that the perimeter distance for the laser cavity is held at a fixed number of wavelengths, but the laser beam translates back and forth across the faces of the mirrors. By this technique, the undesired phenomena of lock-in at low rotation rates is avoided, without the need for special optical or magnetic structures in the path of the laser beam.
Claims15
A ring laser comprising:
- means forming a closed loop optical cavity containing an active lasing medium for generating primary counter-rotating laser light beams therein, the frequency difference between the light beams having a measure of the rate of rotation experienced by the ring laser, said cavity forming means including a plurality of mirrors for reflecting said light beams;
- and
- means for vibrating each of said mirrors in translation at the same frequency in a direction only perpendicular to the surface of the mirror with each said mirror being vibrated at a phase difference with respect to each adjacent mirror substantially equal to 360.degree. divided by the number of mirrors.
A ring laser comprising:
- a ring laser structure of the single mode type having two counter-rotating laser beams and including at least three mirrors:
- means for translating each said mirror in an oscillating mode at the same frequency substantially only in the direction of a line bisecting the beams incident on each said mirror;
- and
- means for phasing the movement of all of said mirrors to maintain constant primary laser beam path length as said mirrors are displaced.
Dependencies are inferred from the claim text.