US4807997A
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Angular displacement measuring interferometer
Assignee: Zygo Corp
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Filing: 1987-11-12
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Granted: 1989-02-28
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Expires: 2007-11-12
Abstract
Abstract An angular displacement interferometer system capable of measuring accurately changes in angular displacement comprises a source (10) of a frequency stabilized input beam with two linear orthogonally polarized components; a tilted parallel plate or shear place (16) with regions of reflection, antireflection, and polarizing coatings for converting the input beam (12) into two separated, parallel, orthogonally polarized beams (30, 31); a half-wave retardation plate (29) located in one of the separated beams (31) for converting the two separated, parallel, orthogonally polarized beams (30, 31); into first and second beams which are spatially separated parallel, and have the same polarization (30, 33); a polarizing beamsplitter (40) and quarter-wave retardation plate (44) for transmitting the first and second beams (34, 35) to a fixed plano mirror (70) nominally perpendicular to the first and second beams for reflecting the first and second beams back into the quarter-wave retardation plate (44), polarizing beamsplitter (40), and retroreflector (48) for producing third and fourth beams (56, 67); a rhomboid-shaped glass element (72 ) attached to the mechanical apparatus whose angular displacement is to be measured, located such that the third and fourth beams enter adjacent faces and are refracted to produce fifth and sixth beams which are reflected from the fixed plano mirror (70) back through the rhomboid-shaped glass element (72) back through the quarter-wave retardation plate (44), beamsplitter (40), retardation plate (29) and shear plate (16) where the fifth and sixth beams are recombined into a single output beam (80) having two orthogonally polarized components in which the phase difference between the two components of the output beam (80) is related to the angular displacement; a polarizer (81) for mixing the orthogonal components of the output beam (80); a photoelectric detector (83) for producing an electrical measurement signal (85); and a phase meter/accumulator (90) for indicating the measured phase (92), the measured phase being related to the angular displacement.
Inventors
- 👤 Gary E. Sommargren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:43
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/02015; G01B9/02017; G01B9/02019; G01B9/02018; G01B9/02055; G01B9/02075; G01B9/02076; G01B9/02077; G01B2290/00; G01B2290/70
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
299 words
An angular displacement interferometer system for accurately measuring changes in angular displacement of a mechanical apparatus, said system comprising a source of a frequency stabilized input beam with two linear orthogonally polarized components; means for converting said input beam into two separated, parallel, orthogonally polarized beams; means located in one of said separated beams for converting said two separated, parallel, orthogonally polarized beams into first and second beams which are spatially separated, parallel, and have the same polarization; means for transmitting said first and second beams; means disposed in the path of said transmitted beams for reflecting said first and second transmitted beams; means disposed in the path of said reflected beams for producing third and fourth beams; refractive means having a plurality of faces, said refractive means being attached to said mechanical apparatus located such that said third and fourth beams enter adjacent faces of said refractive means and are refracted to produce fifth and sixth beams which are reflected from said reflecting means back through said means attached to said mechanical apparatus and back through said refractive means attached to said mechanical apparatus and back through said means for producing said third and fourth beams, said means for converting said two separated beams into said first and second beams having the same polarization and said means for converting said input beams into said two orthogonally polarized beams wherein said fifth and sixth beams are recombined into a single output beam having two orthogonally polarized components in which the phase difference between the two components of said output beam is related to said angular displacement; means for mixing said orthogonal components of said output beam; means for producing an electrical measurement signal; and means for indicating a measured phase, said measured phase being related to said angular displacement.
Claim 2
Dependent Claim
299 words
An angular displacement interferometer system for accurately measuring changes in angular displacement of a mechanical apparatus, said system comprising a source of a frequency stabilized input beam with two linear orthogonally polarized components; means for converting said input beam into two separated, parallel, orthogonally polarized beams; means located in one of said separated beams for converting said two separated, parallel, orthogonally polarized beams into first and second beams which are spatially separated, parallel, and have the same polarization; means for transmitting said first and second beams; means disposed in the path of said transmitted beams for reflecting said first and second transmitted beams; means disposed in the path of said reflected beams for producing third and fourth beams; refractive means having a plurality of faces, said refractive means being attached to said mechanical apparatus located such that said third and fourth beams enter adjacent faces of said refractive means and are refracted to produce fifth and sixth beams which are reflected from said reflecting means back through said means attached to said mechanical apparatus and back through said refractive means attached to said mechanical apparatus and back through said means for producing said third and fourth beams, said means for converting said two separated beams into said first and second beams having the same polarization and said means for converting said input beams into said two orthogonally polarized beams wherein said fifth and sixth beams are recombined into a single output beam having two orthogonally polarized components in which the phase difference between the two components of said output beam is related to said angular displacement; means for mixing said orthogonal components of said output beam; means for producing an electrical measurement signal; and means for indicating a measured phase, said measured phase being related to said angular displacement.
Claim 3
Dependent Claim
20 words
A system in accordance with claim 1 wherein said two polarized components from said source are of the same frequency.
Claim 4
Dependent Claim
19 words
A system in accordance with claim 1 wherein said two polarized components from said source are of different frequencies.
Claim 5
Dependent Claim
25 words
A system in accordance with claim 1 wherein said means for converting said input beam into two orthogonally polarized beams comprises a tilted parallel plate.
Claim 6
Dependent Claim
32 words
A system in accordance with claim 1 wherein said means for converting said input beam into two orthogonally polarized beams comprises a shear plate with regions of reflection, antireflection, and polarizing coatings.
Claim 7
Dependent Claim
32 words
A system in accordance with claim 1 wherein said means for converting said two orthogonally polarized beams into said first and second beams having the same polarization comprises a half-wave retardation plate.
Claim 8
Dependent Claim
19 words
A system in accordance with claim 1 wherein said transmitting means comprises a polarizing beamsplitter and quarter-wave retardation plate.
Claim 9
Dependent Claim
31 words
A system in accordance with claim 1 wherein said means for reflecting said first and second transmitted beams comprises a fixed plano mirror nominally perpendicular to said first and second beams.
Claim 10
Dependent Claim
27 words
A system in accordance with claim 1 wherein said means for producing said third and fourth beams comprises a quarter-wave retardation plate, polarizing beamsplitter and a retroreflector.
Claim 11
Dependent Claim
27 words
A system in accodance with claim 9 wherein said means for transmitting said first and second beams further comprises means for producing said third and fourth beams.
Claim 12
Dependent Claim
26 words
A system in accordance with claim 10 wherein said means for transmitting said first and second beams comprises said polarizing beamsplitter and said quarter-wave retardation plate.
Claim 13
Dependent Claim
21 words
A system in accordance with claim 1 wherein sid refractive means attached to said mechanical apparatus comprises a rhomboid-shaped glass element.
Claim 14
Dependent Claim
18 words
A system in accodance with claim 1 wherein said means for mixing said orthogonal components comprises a polarizer.
Claim 15
Dependent Claim
20 words
A system in accordance with claim 1 wherein said means for producing an electrical measurement signal comprises a photoelectric detector.
Claim 16
Dependent Claim
19 words
A system in accordance with claim 1 wherein said means for indicating a measured phase comprises a phase meter/accumulator.
Claim 17
Dependent Claim
19 words
A system in accordance with claim 6 wherein said transmitting means comprises a polarizing beamsplitter and quarter-wave retardation plate.
Claim 18
Dependent Claim
31 words
A system in accordance with claim 16 wherein said means for reflecting said first and second transmitted beams comprises a fixed plano mirror nominally perpendicular to said first and second beams.
Claim 19
Dependent Claim
28 words
A system in accordance with claim 17 wherein said means for producing said third and fourth beams compries said quarter-wave retardation plate, said polarizing beamsplitter and a retroreflector.
Claim 20
Dependent Claim
27 words
A system in accordance with claim 18 wherein said means for transmitting said first and second beams further comprises means for producing said third and fourth beams.
Claim 21
Dependent Claim
26 words
A system in accordance with claim 19 wherein said means for transmitting said first and second beams comprises said polarizing beamsplitter and said quarter-wave retardation plate.
Claim 22
Dependent Claim
21 words
A system in accordance with claim 20 wherein said refractive means attached to said mechanical apparatus comprises a rhomboid-shaped glass element.
Claim 23
Dependent Claim
18 words
A system in accordance with claim 21 wherein said means for mixing said orthogonal components comprises a polarizer.
Claim 24
Dependent Claim
20 words
A system in accordance with claim 22 wherein said means for producing an electrical measurement signal comprises a photoelectric detector.
Claim 25
Dependent Claim
19 words
A system in accordance with claim 23 wherein said means for indicating a measured phase comprises a phase meter/accumulator.
Claim 26
Dependent Claim
20 words
A system in accordance with claim 24 wherein said two polarized components from said source are of the same frequency.
Claim 27
Dependent Claim
25 words
A system in accordance with claim 25 wherein said means for converting said input beam into two orthogonally polarized beams comprises a tilted parallel plate.
Claim 28
Dependent Claim
32 words
A system in accordance with claim 25 wherein said means for converting said input beam into two orthogonally polarized beams comprises a shear plate with regions of reflection, antireflection, and polarizing coatings.
Claim 29
Dependent Claim
19 words
A system in accordance with claim 24 wherein said two polarized components from said source are of different frequencies.
Claim 30
Dependent Claim
25 words
A system in accordance with claim 28 wherein said means for converting said input beam into two orthogonally polarized beams comprises a tilted parallel plate.
Claim 31
Dependent Claim
32 words
A system in accodance with claim 28 wherein said means for converting said input beam into two orthogonally polarized beams comprises a shear plate with regions of reflection, antireflection, and polarizing coatings.
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) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |