US4881816A
Expired / Lapsed
US
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Linear and angular displacement measuring interferometer
Assignee: Zygo Corp
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Filing: 1988-07-08
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Granted: 1989-11-21
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Expires: 2008-07-08
Abstract
Abstract An interferometer system capable of measuring linear displacement and angular displacement simultaneously of a movable plane mirror (90) comprises a source (10) of a frequency stabilized input beam (12) and includes an optical system which reflects one polarization component of the input beam (12) twice from a first position on the movable plane mirror (90) to produce beams (30) and reflects the other polarization component of the input beam twice from a stationary plane mirror (89) to produce beam (28). A polarization beamsplitter (80) recombines these beams (30, 28) into a beam (66) in which the phase difference between the two components of the third output beam (66) is related to four times the linear displacement of the movable plane mirror (90) at the first position. Beam (66) is divided into beams (119) and (121), with the interference between the two polarization components detected by photodetector (94) to produce a signal (96) from which the phase change is extracted (99) to produce a measured phase which is related to four times the linear displacement of the movable plane mirror (90) at the first position. The polarization beamsplitter (80) and a retroreflector (81) reflect one polarization component of the other beam (121) twice from a second position on the movable plane mirror (90) and reflect the other polarization component of this beam (121) twice from the stationary plane mirror (89) with the beamsplitter (80) recombining the resultant beams into a beam (67) having two orthogonally polarized components in which the phase difference between the two components of the beam is related to four times the sum of the linear displacements of the movable plane mirror (90) at the first and second positions. The interference between the two components of beam (67) is detected by second photo detector (194) to produce a signal (97) for indicating a second measured phase, which is related to four times the sum of the linear displacement of the movable plane mirror (90) at the first and second positions. Electronic module (124) provides the difference between one-half of the second measured phase (101) and the first measured phase (100) to produce a signal (126) related to angular displacement (91) of the movable plane mirror (90).
Inventors
- 👤 Carl A. Zanoni
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:37
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/02015; G01B9/02017; G01B9/02019; G01B11/00; G01B11/26; G01B9/02001; G01B9/02002; G01B9/02003; G01B9/02018; G01B2290/00; G01B2290/70
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
454 words
An interferometer system capable of measuring linear displacement and angular displacement simultaneously of a movable plane mirror comprising a source of a frequency stabilized input beam with two linear orthogonally polarized components; optical system means comprising a stationary plane reference mirror, said optical system being disposed to reflect one polarization component of said input beam twice from a first position on said movable plane mirror to produce a first output beam and to reflect the other polarization component of said input beam twice from said stationary plane mirror to produce a second output beam; means disposed for recombining said first and second output beams into a third output beam having two orthogonally polarized components in which the phase difference between the two components of the third output beam is related to four times the linear displacement of said movable plane mirror at said first position; means to divide said third output beam into a fourth output beam and a fifth beam which is parallel to, spatially displaced from, and traveling in the same direction as said input beam; means disposed for mixing said orthogonal components of said fourth output beam; means disposed to produce a first electrical measurement signal; means associated with said first electrical measurement signal for indicating a first measured phase, said first measured phase being related to four times the linear displacement of said movable plane mirror at said first position; means disposed to reflect one polarization component of said fifth beam twice from a second position on said movable plane mirror to produce a sixth output beam and to reflect the other polarization component of said fifth beam twice from said stationary plane mirror to produce a seventh output beam; means disposed for recombining said sixth and seventh output beams into an eighth output beam having two orthogonally polarized components in which the phase difference between the two components of the eighth output beam is related to four times the sum of the linear displacements of said movable plane mirror at said first and second positions; means disposed for mixing said orthogonal components of said eighth output beam; means disposed to produce a second electrical measurement signal; means associated with said second electrical measurement signal for indicating a second measured phase, said second measured phase being related to four times the sum of the linear displacement of said movable plane mirror at said first and second positions; and means disposed to form the difference between one-half of said second measured phase and said first measured phase to produce a signal related to the angular displacement of said movable plane mirror; whereby said linear and angular displacement of said movable plane mirror may be accurately measured in a single interferometer system.
Claim 2
Dependent Claim
454 words
An interferometer system capable of measuring linear displacement and angular displacement simultaneously of a movable plane mirror comprising a source of a frequency stabilized input beam with two linear orthogonally polarized components; optical system means comprising a stationary plane reference mirror, said optical system being disposed to reflect one polarization component of said input beam twice from a first position on said movable plane mirror to produce a first output beam and to reflect the other polarization component of said input beam twice from said stationary plane mirror to produce a second output beam; means disposed for recombining said first and second output beams into a third output beam having two orthogonally polarized components in which the phase difference between the two components of the third output beam is related to four times the linear displacement of said movable plane mirror at said first position; means to divide said third output beam into a fourth output beam and a fifth beam which is parallel to, spatially displaced from, and traveling in the same direction as said input beam; means disposed for mixing said orthogonal components of said fourth output beam; means disposed to produce a first electrical measurement signal; means associated with said first electrical measurement signal for indicating a first measured phase, said first measured phase being related to four times the linear displacement of said movable plane mirror at said first position; means disposed to reflect one polarization component of said fifth beam twice from a second position on said movable plane mirror to produce a sixth output beam and to reflect the other polarization component of said fifth beam twice from said stationary plane mirror to produce a seventh output beam; means disposed for recombining said sixth and seventh output beams into an eighth output beam having two orthogonally polarized components in which the phase difference between the two components of the eighth output beam is related to four times the sum of the linear displacements of said movable plane mirror at said first and second positions; means disposed for mixing said orthogonal components of said eighth output beam; means disposed to produce a second electrical measurement signal; means associated with said second electrical measurement signal for indicating a second measured phase, said second measured phase being related to four times the sum of the linear displacement of said movable plane mirror at said first and second positions; and means disposed to form the difference between one-half of said second measured phase and said first measured phase to produce a signal related to the angular displacement of said movable plane mirror; whereby said linear and angular displacement of said movable plane mirror may be accurately measured in a single interferometer system.
Claim 3
Dependent Claim
18 words
An interferometer system in accordance with claim 1 wherein said frequency stabilized input beam source comprises a laser.
Claim 4
Dependent Claim
19 words
An interferometer system in accordance with claim 2 wherein said input beam components are of the same optical frequency.
Claim 5
Dependent Claim
18 words
An interferometer system in accordance with claim 2 wherein said input beam components are of different optical frequencies.
Claim 6
Dependent Claim
19 words
An interferometer system in accordance with claim 1 wherein said input beam components are of the same optical frequency.
Claim 7
Dependent Claim
18 words
An interferometer system in accordance with claim 1 wherein said input beam components are of different optical frequencies.
Claim 8
Dependent Claim
46 words
An interferometer system in accordance with claim 4 wherein said input source further comprises means for providing an electrical reference signal to said means for indicating said first and second measured phases, said reference signal corresponding to the frequency difference between said two different stabilized frequencies.
Claim 9
Dependent Claim
46 words
An interferometer system in accordance with claim 6 wherein said input source further comprises means for providing an electrical reference signal to said means for indicating said first and second measured phases, said reference signal corresponding to the frequency difference between said two different stabilized frequencies.
Claim 10
Dependent Claim
18 words
An interferometer system in accordance with claim 1 wherein said optical system means further comprises a polarization beamsplitter.
Claim 11
Dependent Claim
20 words
An interferometer system in accordance with claim 9 wherein said optical system means further comprises two quarter-wave phase retardation plates.
Claim 12
Dependent Claim
18 words
An interferometer system in accordance with claim 10 wherein said optical system means further comprises a first retroreflector.
Claim 13
Dependent Claim
18 words
An interferometer system in accordance with claim 2 wherein said optical system means further comprises a polarization beamsplitter.
Claim 14
Dependent Claim
28 words
An interferometer system in accordance with claim 9 wherein said means for recombining said first and second output beams into said third output beam comprises said polarization beamsplitter.
Claim 15
Dependent Claim
28 words
An interferometer system in accordance with claim 12 wherein said means for recombining said first and second output beams into said third output beam comprises said polarization beamsplitter.
Claim 16
Dependent Claim
25 words
An interferometer system in accordance with claim 1 wherein said means for mixing said orthogonal components of said fourth output beam comprises a first polarizer.
Claim 17
Dependent Claim
25 words
An interferometer system in accordance with claim 2 wherein said means for mixing said orthogonal components of said fourth output beam comprises a first polarizer.
Claim 18
Dependent Claim
23 words
An interferometer system in accordance with claim 1 wherein said means for producing said first electrical measurement signal comprises a first photoelectric detector.
Claim 19
Dependent Claim
23 words
An interferometer system in accordance with claim 2 wherein said means for producing said first electrical measurement signal comprises a first photoelectric detector.
Claim 20
Dependent Claim
22 words
An interferometer system in accordance with claim 1 wherein said means for indicating said first measured phase comprises a first phase meter/accumulator.
Claim 21
Dependent Claim
22 words
An interferometer system in accordance with claim 2 wherein said means for indicating said first measured phase comprises a first phase meter/accumulator.
Claim 22
Dependent Claim
26 words
An interferometer system in accordance with claim 1 wherein said means for producing said sixth and seventh output beams comprises said optical system and a retroreflector.
Claim 23
Dependent Claim
26 words
An interferometer system in accordance with claim 2 wherein said means for producing said sixth and seventh output beams comprises said optical system and a retroreflector.
Claim 24
Dependent Claim
16 words
An interferometer system in accordance with claim 21 wherein said optical system means comprises another retroreflector.
Claim 25
Dependent Claim
16 words
An interferometer system in accordance with claim 22 wherein said optical system means comprises another retroreflector.
Claim 26
Dependent Claim
18 words
An interferometer system in accordance with claim 23 wherein said optical system means further comprises a polarization beamsplitter.
Claim 27
Dependent Claim
18 words
An interferometer system in accordance with claim 24 wherein said optical system means further comprises a polarization beamsplitter.
Claim 28
Dependent Claim
23 words
An interferometer system in accordance with claim 23 wherein said means for recombining said sixth and seventh output beam comprises said polarization beamsplitter.
Claim 29
Dependent Claim
23 words
An interferometer system in accordance with claim 26 wherein said means for recombining said sixth and seventh output beam comprises said polarization beamsplitter.
Claim 30
Dependent Claim
23 words
An interferometer system in accordance with claim 9 wherein said means for recombining said sixth and seventh output beam comprises said polarizatiuon beamsplitter.
Claim 31
Dependent Claim
18 words
An interferometer system in accordance with claim 29 wherein said frequency stabilized input beam source comprises a laser.
Claim 32
Dependent Claim
18 words
An interferometer system in accordance with claim 26 wherein said optical system means further comprises a polarization beamsplitter.
Claim 33
Dependent Claim
18 words
An interferometer system in accordance with claim 2 wherein said optical system means further comprises a polarization beamsplitter.
Claim 34
Dependent Claim
18 words
An interferometer system in accordance with claim 15 wherein said optical system means further comprises a polarization beamsplitter.
Claim 35
Dependent Claim
18 words
An interferometer system in accordance with claim 16 wherein said optical system means further comprises a polarization beamsplitter.
Claim 36
Dependent Claim
22 words
An interferometer system in accordance with claim 1 wherein said means for producing said second electrical measurement signal comprises a second photodetector.
Claim 37
Dependent Claim
22 words
An interferometer system in accordance with claim 2 wherein said means for producing said second electrical measurement signal comprises a second photodetector.
Claim 38
Dependent Claim
22 words
An interferometer system in accordance with claim 1 wherein said means for indicating a second measured phase comprises a second phase meter/accumulator.
Claim 39
Dependent Claim
22 words
An interferometer system in accordance with claim 2 wherein said means for indicating a second measured phase comprises a second phase meter/accumulator.
References Cited (Backward Citations)
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