Phase conjugation using internal reflection

Claim 3

The method of claim 1 wherein the auxiliary beam is internally reflected at least twice by the surface of the material before returning to the incoming beam.

Claim 4

The method of claim 1 wherein the incoming light has a coherence length at least as long as the path of the auxiliary beam within the material.

Claim 5

The method of claim 3 which further comprises the step of securing the body of mixing material in the orientation achieved in the adjustment step.

Claim 6

The method of claim 4 in which the body of mixing material is a right cylindrical body having a preselected axis and the beams are directed along a plane perpendicular to the axis.

Claim 7

The method of claim 5 in which the body of mixing material has a substantially rectangular transverse cross section defining four corners and the internal reflection takes place adjacent to at least one of the corners.

Claim 8

The method of claim 6 wherein the mixing material is crystalline barium titanate.

Claim 9

The method of claim 6 wherein the mixing material is crystalline potassium niobium tantalate.

Claim 10

The method of claim 6 wherein the mixing material is crystalline strontium barium niobate.

Claim 11

The method recited in claim 4 which further comprises the step of applying an external electric field to the material.

Claim 16

In a laser apparatus having a gain medium, means for exciting the gain medium and a plurality of means for reflecting a light beam through the gain medium to produce oscillation, the improvement wherein at least one of the reflecting means comprises a body of mixing material which lacks inversion symmetry and has an optical coupling strength of at least approximately one per millimeter, the body being aligned with the light beam such that at least one auxiliary beam splits off from the incoming beam within the material, is internally reflected by the surface of the body and returns to said light beam within the material for scattering as an oppositely directed phase conjugate replica of said light beam.

Claim 17

In a laser apparatus having a gain medium, means for exciting the gain medium and a plurality of means for reflecting a light beam through the gain medium to produce oscillation, the improvement wherein at least one of the reflecting means comprises a body of mixing material which lacks inversion symmetry and has an optical coupling strength of at least approximately one per millimeter, the body being aligned with the light beam such that at least one auxiliary beam splits off from the incoming beam within the material, is internally reflected by the surface of the body and returns to said light beam within the material for scattering as an oppositely directed phase conjugate replica of said light beam.

Claim 18

The laser apparatus recited in claim 13 wherein said at least one reflecting means consists essentially of said body of mixing material and means for directing said light beam to the body and directing said replica beam back to the gain medium.

Claim 19

In a photolithographic apparatus having means for exposing a mask to substantially collimated light and directing a transmitted primary beam along a preselected path to a work surface, the improvement which comprises: a body of mixing material which lacks inversion symmetry and has an optical coupling strength of at least approximately one per millimeter, the body being aligned with the primary beam at a location along the preselected path such that at least one auxiliary beam splits off from the primary beam within the material, is internally reflected by the surface of the body and returns to the primary beam within the material for scattering as an oppositely directed phase conjugate replica beam of the primary beam; and means for splitting off at least a portion of the replica beam for selective illumination of the work surface.

Claim 20

In a photolithographic apparatus having means for exposing a mask to substantially collimated light and directing a transmitted primary beam along a preselected path to a work surface, the improvement which comprises: a body of mixing material which lacks inversion symmetry and has an optical coupling strength of at least approximately one per millimeter, the body being aligned with the primary beam at a location along the preselected path such that at least one auxiliary beam splits off from the primary beam within the material, is internally reflected by the surface of the body and returns to the primary beam within the material for scattering as an oppositely directed phase conjugate replica beam of the primary beam; and means for splitting off at least a portion of the replica beam for selective illumination of the work surface.

Claim 21

The apparatus of claim 13 or 15 wherein the mixing material is a right cylindrical body having a preselected axis and the beams are directed along a plane perpendicular to the axis.

Claim 22

The apparatus of claim 16 wherein the body of mixing material has a substantially rectangular transverse cross section defining four corners and the internal reflection takes place adjacent at least one of the corners.

Claim 23

The apparatus recited in claim 17 wherein the mixing material comprises crystalline barium titanate.

Claim 24

The apparatus recited in claim 17 wherein the mixing material comprises crystalline potassium niobium tantalate.

Claim 25

The apparatus recited in claim 17 wherein the mixing material comprises crystalline strontium barium niobate.

Claim 26

The apparatus recited in claim 13 or 15 which further comprises means for applying an electric field to the material.