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US4881815A
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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 A single interferomter system capable of measuring accurately linear displacement and angular displacement simultaneously of a movable plane mirror (90) comprises a source (10) of a frequency stabilized input beam (12), a polarization beamsplitter (80), two quarter-wave plates (88, 108), a mirror (89), and a retroreflector (81), to reflect one polarization component of the input beam (12) twice from the movable mirror (90) to produce a first output beam and to reflect the other polarization component of the input beam (12) twice from the stationary mirror (89) to produce a second output beam. The beamsplitter (80) recombines the output beams into a third output beam having two orthogonally polarized components related to the linear displacement of the movable mirror (90) at the first position. The third output beam is divided into a fourth output beam and a fifth beam parallel to, spatially displaced from, and traveling in the same direction as the input beam (12) and has its polarization components rotated by 90 degrees from the third output beam. The interference between the components of the fourth beam is detected by photodetector (94) and the phase change is extracted from the resultant signal (96, 99) with the measured phase being related to the linear displacement of the mirror (90) at the first position. A second photoelectric detector (194) produces a signal from which the phase change is extracted from the resultant signal (97, 109) with the second measured phase related to the angular displacement of the movable plane mirror (90).
Inventors
- 👤 Gary E. Sommargren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:23
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/02015; G01B9/02017; G01B9/02019; G01B9/02018; G01B2290/00; G01B2290/70
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
424 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; an optical system means comprising a stationary plane reference mirror, said optical system means 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 beam 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 disposed to divide said third output beam into a fourth output beam and a fifth beam which is parallel to, spatially displaced from, traveling in the same direction as said input beam, and has its polarization components rotated from said third output 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 recombing said sixth and seventh output beams into an eighth output beam having two orthogonally polarized components in which the phase difference between said two components of said eighth output beam is related to four times the difference of the linear displacements of said movable plane mirror at said first and second position; means disposed for mixing said orthogonal components of said eighth output beam; means disposed to produce a second electrical measurement signal; and means associated with such second electrical measurement signal for indicating a second measured phase, said second measured phase being related to the angular displacement of said movable plane mirror; whereby said linear and angular displacement of said movable plane mirror may be simultaneously accurately measured in a single interferometer system.
Claim 2
Dependent Claim
424 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; an optical system means comprising a stationary plane reference mirror, said optical system means 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 beam 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 disposed to divide said third output beam into a fourth output beam and a fifth beam which is parallel to, spatially displaced from, traveling in the same direction as said input beam, and has its polarization components rotated from said third output 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 recombing said sixth and seventh output beams into an eighth output beam having two orthogonally polarized components in which the phase difference between said two components of said eighth output beam is related to four times the difference of the linear displacements of said movable plane mirror at said first and second position; means disposed for mixing said orthogonal components of said eighth output beam; means disposed to produce a second electrical measurement signal; and means associated with such second electrical measurement signal for indicating a second measured phase, said second measured phase being related to the angular displacement of said movable plane mirror; whereby said linear and angular displacement of said movable plane mirror may be simultaneously 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 sources 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
17 words
An interferometer system in accordance with claim 2 wherein said input beam components are 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
17 words
An interferometer system in accordance with claim 1 wherein said input beam components are 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
15 words
An interferometer system in accordance with claim 21 wherein said optical system comprises another retroreflector.
Claim 25
Dependent Claim
15 words
An interferometer system in accordance with claim 22 wherein said optical system 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
28 words
An interferometer system in accordance with claim 25 wherein said means for recombining said sixth and seventh output beams into an eighth output beam comprises said polarization beamsplitter.
Claim 29
Dependent Claim
28 words
An interferometer system in accordance with claim 26 wherein said means for recombining said sixth and seventh output beams into an eight output beam comprises said polarization beamsplitter.
Claim 30
Dependent Claim
28 words
An interferometer system in accordance with claim 9 wherein said means for recombining said sixth and seventh output beams into an eighth output beam comprises said polarization 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
25 words
An interferometer system in accordance with claim 1 wherein said means for mixing said orthogonal components of said eighth output beam comprises a second polarizer.
Claim 33
Dependent Claim
25 words
An interferometer system in accordance with claim 2 wherein said means for mixing said orthogonal components of said eighth output beam comprises a second polarizer.
Claim 34
Dependent Claim
25 words
An interferometer system in accordance with claim 15 wherein said means for mixing said orthogonal components of said eighth output beam comprises a second polarizer.
Claim 35
Dependent Claim
25 words
An interferometer system in accordance with claim 16 wherein said means for mixing said orthogonal components of said eighth output beam comprises a second polarizer.
Claim 36
Dependent Claim
22 words
An interferometer system in accordance with claim 1 wherein said means for producing said second electrical measurements 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
23 words
An interferometer system in accordance with claim 1 wherein said means for indicating a second measured second 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.
Claim 40
Dependent Claim
64 words
An interferometer system in accordance with claim 1 wherein said dividing means for said third output beam comprises means for dividing said third output beam into said fourth output beam and said fifth beam which is parallel to, spatially displaced from, traveling in the same direction as said input beam, and has its polarization components rotated by 90 degrees from said third output beam.
Claim 41
Dependent Claim
64 words
An interferometer system in accordance with claim 2 wherein said dividing means for said third output beam comprises means for dividing said third output beam into said fourth output beam and said fifth beam which is parallel to, spatially displaced from, traveling in the same direction as said input beam, and has its polarization components rotated by 90 degrees from said third output beam.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-11-20 | 1993-05-22 | 1993-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-20 | 1997-05-22 | 1997-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-20 | 2001-05-22 | 2001-11-21 | $7700.00 | Window Closed / Lapsed |