Method and means for compensating birefringence in laser systems

Claim 3

Means for compensating birefringence induced by thermal stress in a laser material, comprising: a. compensating material of physical properties similar to that of said laser material; b. heating means for applying heat to said compensating material at points to establish thermal gradients in said material in directions to induce artificial stress in a sense opposite to thermal stress developed in said laser material; and c. means for changing the heat applied by said heating means until the birefringence artificially induced by said artificial thermal stress cancels the birefringence induced by thermal stress in said laser material when said compensating material is disposed within an optical cavity incorporating said laser material and is in optical alignment with said laser material whereby increased power output from said laser material is provided over that obtained in the absence of said compensating material.

Claim 4

Means for compensating birefringence induced by thermal stress in a laser material, comprising: a. compensating material of physical properties similar to that of said laser material; b. heating means for applying heat to said compensating material at points to establish thermal gradients in said material in directions to induce artificial stress in a sense opposite to thermal stress developed in said laser material; and c. means for changing the heat applied by said heating means until the birefringence artificially induced by said artificial thermal stress cancels the birefringence induced by thermal stress in said laser material when said compensating material is disposed within an optical cavity incorporating said laser material and is in optical alignment with said laser material whereby increased power output from said laser material is provided over that obtained in the absence of said compensating material.

Claim 5

The subject matter of claim 2, in which said compensating material is in the form of a disc member, said heating means including a thermally conducting ring of metal in intimate thermally conductive contact with the periphery of said disc member; and electrical heating elements mounted on said ring for heating said ring to thereby establish radial inwardly directed thermal gradients; and in wHich said means for changing the heat applied includes electrical control means connected to said electrical heating elements for varying the current supplied thereto.

Claim 6

A laser system comprising, in combination: a. a laser material; b. light pumping means for inducing an inverted population level of laser ions in said material; c. first and second end mirrors positioned in optical alignment with said material to define an optical cavity; d. a compensating material of physical properties similar to that of said laser material disposed in said optical cavity in optical alignment with said laser material; e. artificial heating means connected to said compensating material at positions to establish thermal gradients in said compensating material in directions to induce artificial thermal stress in a sense opposite to thermal stress developed in said laser material by said light pumping means; and f. control means connected to said heating means for changing the degree of heat and thereby the birefringence induced by said artificial thermal stress in said compensating material until it substantially cancels the thermally induced birefringence in said laser material.

Claim 7

A laser system comprising, in combination: a. a laser material; b. light pumping means for inducing an inverted population level of laser ions in said material; c. first and second end mirrors positioned in optical alignment with said material to define an optical cavity; d. a compensating material of physical properties similar to that of said laser material disposed in said optical cavity in optical alignment with said laser material; e. artificial heating means connected to said compensating material at positions to establish thermal gradients in said compensating material in directions to induce artificial thermal stress in a sense opposite to thermal stress developed in said laser material by said light pumping means; and f. control means connected to said heating means for changing the degree of heat and thereby the birefringence induced by said artificial thermal stress in said compensating material until it substantially cancels the thermally induced birefringence in said laser material.

Claim 8

A system according to claim 4, in which said laser material comprises a solid state rod of given diameter, said compensating material being in the form of a disc member of diameter at least equal to said given diameter, said heating means including a thermally conducting ring of metal in intimate thermally conductive contact with the periphery of said disc member; and electrical heating elements mounted on said ring for heating said ring to thereby establish radial inward directions for said thermal gradients; and in which said control means includes electrical means connected to said electrical heating elements for varying the current supplied thereto.

Claim 9

A system according to claim 5, in which said disc material comprises glass.

Claim 10

A system according to claim 5, in which said rod comprises a yttrium-aluminum-garnet host crystal doped with neodymium ions and in which said disc member comprises undoped yttrium-aluminum-garnet.