Partially transparent mirror for a ring laser
AssigneeLitton Systems, Inc.
InventorsSamuel Lu, Kevin D. Grobsky
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Abstract
Provided herein is a ring laser gyro system having a special and improved partially transparent output mirror which provides relatively undistorted circularly polarized coherent light beams to the photo detector and amplifier of the system from the laser cavity thereof. This improved mirror achieves its results by sandwiching a non-quarterwave stack between two quarterwave stacks of multi layer, all of which are coated on a Zerodur substate mirror. The improved mirror achieves nearly Zero phase retardation and a Tp/Ts ratio equal to one.
Claims12
A specialized partially transparent mirror for use in a multioscillator gyro operating at a predetermined wave length, comprising:
- a substrate;
- a first set of a plurality of layers coated upon said substrate, each layer of said first set having a thickness that is one quarter of said predetermined wavelengths;
- a second set of a plurality of layers coated upon said first set, each layer of said second set having a thickness other than one quarter of said predetermined wavelength;
- a second set of a plurality of layers coated upon said second set, each layer of said third set having a thickness that is one quarter of said predetermined wavelength;
- and
- said second and said third sets of a plurality of layers adjusted to establish said partially transparent mirror with an average transmission of 0.02% and a transmission ratio of P - polarized light to S - polarized light at near unity.
A system for minimizing the distortion of an output signal from a multioscillator laser gyro, comprising:
- a resonant laser cavity;
- means for propagating counter-rotating laser beams within said cavity;
- a plurality of mirrors mounted within said laser cavity for directing said laser beams within said laser cavity at an angle of incidence between 30.degree. to 40.degree.;
- at least one of said mirrors being partially transparent to allow the passage of said laser beams outside said cavity;
- said partially transparent mirror having:
- a substrate;
- a first set of plurality of layers positioned upon said substrate, each layer of said first set being a quarterwave length, said first set being a quarterwave stack;
- a second set of a plurality of layers positioned upon said first set, said second set being a non-quarterwave stack;
- a third set of a plurality of layers positioned upon said second set, each layer of said third set being a quarterwave length, said third set being a quarterwave stack;
- and
- said second set of a plurality of layers adjusted to establish said partially transparent mirror with a transmission ration of P -- polarized light to S -- polarized light at near unity.
Dependencies are inferred from the claim text.