Acousto optic method and apparatus for mode decoupling a ring laser

Claim 2

A ring laser comprising: means for defining an optical ring path; means, including a laser gain medium positioned in said optical ring path, for producing laser light beams counter rotating about said optical ring path; and acousto-optic means positioned in said optical ring path for substantially collinearly diffracting the counter rotating laser light beams on acoustic waves in said acousto-optic means to shift apart the optical frequencies of the counter rotating laser light beams in the laser gain medium by a frequency related to the frequency of the acoustic waves to prevent frequency locking of the optical frequencies of the counter rotating laser light beams.

Claim 3

A ring laser comprising: means for defining an optical ring path; means, including a laser gain medium positioned in said optical ring path, for producing laser light beams counter rotating about said optical ring path; and acousto-optic means positioned in said optical ring path for substantially collinearly diffracting the counter rotating laser light beams on acoustic waves in said acousto-optic means to shift apart the optical frequencies of the counter rotating laser light beams in the laser gain medium by a frequency related to the frequency of the acoustic waves to prevent frequency locking of the optical frequencies of the counter rotating laser light beams.

Claim 4

A ring laser comprising: means for defining an optical ring path; means, including a laser gain medium positioned in said optical ring path, for producing laser light beams counter rotating about said optical ring path; and acousto-optic means positioned in said optical ring path for substantially collinearly diffracting the counter rotating laser light beams on acoustic waves in said acousto-optic means to shift apart the optical frequencies of the counter rotating laser light beams in the laser gain medium by a frequency related to the frequency of the acoustic waves to prevent frequency locking of the optical frequencies of the counter rotating laser light beams.

Claim 5

A ring laser as in claim 1 wherein: said acousto-optic means includes first and second acousto-optic filters, one of said acousto-optic filters being arranged to shift the frequency of the clockwise rotating laser light beam up in frequency and the other of said acousto-optic filters being arranged to shift the frequency of the counterclockwise rotating laser light beam down in frequency; and said laser gain medium is disposed in said optical ring path between said first and second acousto-optic filters.

Claim 6

A ring laser as in claim 2 wherein each of said acousto-optic filters includes: an optically anisotropic medium disposed to receive one of the counter rotating laser light beams of a first polarization; means for producing in the optically anisotropic medium an acoustic wave that is collinear with the path of the laser light beam of the first polarization in the optically anisotropic medium; said optically anisotropic medium substantially collinearly diffracting the laser light beam of the first polarization on the acoustic wave to shift the polarization of the diffracted laser light beam to a second polarization; and means for polarization analyzing the collinearly diffracted laser light beam to filter out light therein that was not shifted from the first polarization to the second polarization.

Claim 7

A ring laser as in claim 3 wherein said optically anisotropic medium is an optically birefringent medium.

Claim 8

A ring laser as in claim 4 wherein said birefringent medium is a birefringent crystal.

Claim 9

A ring laser as in claim 5 including: means for withdrawing a portion of each of the counter rotating laser light beams from said optical ring path; and means for comparing the optical frequencies of the withdrawn portions of the counter rotating laser light beams to obtain an output representative of the frequency difference between the optical frequencies of the counter rotating laser light beams.