Method of testing a length, angle, path difference or speed by detecting interference and apparatus therefor

Claim 2

Method of testing a length, angle, path difference or speed by two-beam detecting interference, comprising the steps of: a. generating two coherent partial beams comprising a reference beam and a measuring beam having polarization states which are complementary to one another and combining said reference and measuring beams to travel substantially in the same direction; b. separating said combined beam at a separating location into at least first and second signal beams unchanged in the pair of complementary states of polarization and each comprising said reference and measuring beam; c. bringing about interference in said first and second signal beams by passing the beams through linearly polarizing analyzing means; d. making a polarization phase shifting between said first and second signal beams thus generating at least first and second optical signals for said first signal beam and third and fourth optical signals for said second signal beam, each of said optical signals having reference and measuring beam components and a polarization state which is offset from one another by an anlge other than 180*; and e. evaluating the difference between said first and second optical signals, and said third and fourth optical signals by photoelectric means wherein said differences are proportional to said length, angle, path difference or speed.

Claim 3

The method of claim 1, wherein in the combined beam the relative phase angle of the two complementary vibrating beam components is varied by optical elements generating a controllable, variable difference between the two components.

Claim 4

The method of claim 1, wherein in the interference device more than two coherent partial beams are generated, and wherein partial beams generated in the same plane are combined in pairs to give them complementary vibrating states of polarization.

Claim 5

The method of claim 1, wherein said separating of steps (b) is carried out geometrically with lenses.

Claim 6

The method of claim 1, wherein said separating of step (b) is carried out physically with a polarizing divider.

Claim 7

The method of claim 1, wherein said polarization phase change of step (d) is carried out by passing one of said signal beams through optically anisotropic materials.

Claim 8

Apparatus for resting a length, angle, path difference or speed by two-beam detecting interference, comprising: a. means for generating at least two coherent partial beams comprising a reference beam and a measuring beam having linear polarization states whicH are complementary to one another; b. means for combining said two partial beams so as to travel as a combined beam in substantially the same direction; c. beam splitting means in the path of said combined beams for separating said combined beams into at least first and second signal beams; d. a linearly polarizing analyzer in the path of each signal beam for bringing about an interference within each signal beam, and generating at least first and second optical signals for said first signal beam and third and fourth optical signals for said second signal beam, each of said optical signals having reference and measuring beam componets; e. optically anisotropic elements positioned in the path of one of said signal beams for making different the path difference between the components vibrating in complementary direction to one another and phase shifting said first signal beam offset relative to said second signal beam by an angle other than 180*; and f. photoelectric means for evaluating the difference between said first and second signal beams, said first and second optical signals, and said third and fourth optical signals wherein said differences are proportional to said length, angle, path difference or speed.

Claim 9

Apparatus for resting a length, angle, path difference or speed by two-beam detecting interference, comprising: a. means for generating at least two coherent partial beams comprising a reference beam and a measuring beam having linear polarization states whicH are complementary to one another; b. means for combining said two partial beams so as to travel as a combined beam in substantially the same direction; c. beam splitting means in the path of said combined beams for separating said combined beams into at least first and second signal beams; d. a linearly polarizing analyzer in the path of each signal beam for bringing about an interference within each signal beam, and generating at least first and second optical signals for said first signal beam and third and fourth optical signals for said second signal beam, each of said optical signals having reference and measuring beam componets; e. optically anisotropic elements positioned in the path of one of said signal beams for making different the path difference between the components vibrating in complementary direction to one another and phase shifting said first signal beam offset relative to said second signal beam by an angle other than 180*; and f. photoelectric means for evaluating the difference between said first and second signal beams, said first and second optical signals, and said third and fourth optical signals wherein said differences are proportional to said length, angle, path difference or speed.

Claim 10

Apparatus for testing a length, angle, path difference or speed by two-beam detecting interference, comprising: a. means for generating at least two coherent partial beams comprising a measuring beam and a reference beam having circular polarization states which are complementary to one another; b. means for combining said reference and measuring beams so as to travel as a combined beam in substantially the same direction; c. beam splitting means in the path of said combined beams for separating said combined beams into at least a first signal beam and a second signal beam; d. a linearly polarizing analyzer in the path of each signal beam for bringing about an interference within each signal beam and generating at least first and second optical signals for said first signal beam and third and fourth optical signals for said second signal beam, each of said optical signals having reference and measuring beam components; e. optically active means for active complimentary polarization states of said first signal beam; and f. photoelectric means for evaluating the difference between said first and second signal beams, said first and second optical signals, and said third and fourth optical signals wherein said differences are proportional to said length, angle, path difference or speed.

Claim 11

Apparatus for testing a length, angle, path difference or speed by two-beam detecting interference, comprising: a. means for generating at least two coherent partial beams comprising a measuring beam and a reference beam having circular polarization states which are complementary to one another; b. means for combining said reference and measuring beams so as to travel as a combined beam in substantially the same direction; c. beam splitting means in the path of said combined beams for separating said combined beams into at least a first signal beam and a second signal beam; d. a linearly polarizing analyzer in the path of each signal beam for bringing about an interference within each signal beam and generating at least first and second optical signals for said first signal beam and third and fourth optical signals for said second signal beam, each of said optical signals having reference and measuring beam components; e. optically active means for active complimentary polarization states of said first signal beam; and f. photoelectric means for evaluating the difference between said first and second signal beams, said first and second optical signals, and said third and fourth optical signals wherein said differences are proportional to said length, angle, path difference or speed.

Claim 12

The apparatus of claim 8, wherein said optically active means of (e) is a polarizer.

Claim 13

The apparatus of claim 8, wherein said optically active means of (e) is an anisotropic lens.