US3635552A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical interferometer
Assignee: US Philips Corp
•
Filing: 1970-04-14
•
Granted: 1972-01-18
•
Expires: 1990-04-14
Abstract
Abstract An interferometer employing a beam splitter, and means for circularly polarizing the split beams into mutually opposite directions. The circularly polarized beams are redirected to an analyzer, preferably rotational, to generate a phase interference pattern which is detected by photodetection devices.
Inventors
- 👤 Hendrik De Lang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:00
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/02015; G01B9/02032; G01B2290/00; G01B2290/70
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
263 words
An optical interferometer including an object surface and a reference surface for measuring object displacement comprising, a source of light, first optical means arranged in the optical path of said source of light for dividing said light into first and second spatially separate partial beams, one of said partial beams striking the surface of said object and being reflected therefrom the other of said beams striking said reference surface and reflecting therefrom, second optical means arranged in the path of each of said partial beams for converting said beams into linearly polarized light prior to striking the respective surfaces, third optical means in the path of each of said reflected partial beams for converting said linearly polarized light into circularly polarized light, each of said beams being circularly polarized in mutually opposite senses of rotation, each of said partial beams after said conversion into circularly polarized light striking said first optical means and thereby being recombined into one linear oscillation having a split field pattern of two component beams impinging upon an analyzer positioned in the path of said recombined beam in front of said object image field, said analyzer rotating uniformly relative to said split field pattern to produce a first and second signal having a phase difference equal to the optical phase difference between said two component beams, and first and second photo detection means positioned in respective ones of said split field on the side of said analyzer oPposite the side upon which said two component beams are incident and proximate said image field for electrically detecting said phase difference.
Claim 2
Dependent Claim
263 words
An optical interferometer including an object surface and a reference surface for measuring object displacement comprising, a source of light, first optical means arranged in the optical path of said source of light for dividing said light into first and second spatially separate partial beams, one of said partial beams striking the surface of said object and being reflected therefrom the other of said beams striking said reference surface and reflecting therefrom, second optical means arranged in the path of each of said partial beams for converting said beams into linearly polarized light prior to striking the respective surfaces, third optical means in the path of each of said reflected partial beams for converting said linearly polarized light into circularly polarized light, each of said beams being circularly polarized in mutually opposite senses of rotation, each of said partial beams after said conversion into circularly polarized light striking said first optical means and thereby being recombined into one linear oscillation having a split field pattern of two component beams impinging upon an analyzer positioned in the path of said recombined beam in front of said object image field, said analyzer rotating uniformly relative to said split field pattern to produce a first and second signal having a phase difference equal to the optical phase difference between said two component beams, and first and second photo detection means positioned in respective ones of said split field on the side of said analyzer oPposite the side upon which said two component beams are incident and proximate said image field for electrically detecting said phase difference.
Claim 3
Dependent Claim
14 words
The combination of claim 1 wherein said first optical means is a semipermeable mirror.
Claim 4
Dependent Claim
25 words
The combination of claim 1 wherein said second optical means is a linear polarized position in the path of said first and second partial beams.
Claim 5
Dependent Claim
50 words
The combination of claim 2 wherein said third optical means is a (n/4) lambda plate (n odd) positioned in the path of said first and second partial beams, each (n/4) lambda plate set with their main directions at a diagonal with the direction of polarization of the polarizer associated therewith.
Claim 6
Dependent Claim
253 words
An optical interferometer for measuring object displacement comprising a source of light, first optical means arranged in the optical path of said source of light for providing a first linearly polarized beam of light, a semipermeable mirror in the path of said linearly polarized beam for reflecting said beam to a second optical means positioned in the path of said first linearly polarized beam of light, the path of said linearly polarized beam of light thereafter terminating at said object and reflecting therefrom back through said second optical means and said mirror, said second optical means dividing said beam into first and second spatially separate beams having respective directions of oscillation at right angles to each other, third optical means positioned in the path of said first and second beams between said second optical means and the image field of said object for converting said two spatially separate linearly polarized beams into two circularly polarized beams having mutually opposite senses of rotation, said two circularly polarized beams together providing a split field impinging upon an analyzer, said analyzer positioned in the path of said beams before said image field and rotating with respect to and about an axis parallel to the common incidence of said counterrotating beams, first and second detectors each positioned in a respective one of said split field and substantially coincident with said field and having produced therein electric signals, having a phase difference equal to the optical phase difference between the said partial beams, produced by said rotating analyzer.
Claim 7
Dependent Claim
253 words
An optical interferometer for measuring object displacement comprising a source of light, first optical means arranged in the optical path of said source of light for providing a first linearly polarized beam of light, a semipermeable mirror in the path of said linearly polarized beam for reflecting said beam to a second optical means positioned in the path of said first linearly polarized beam of light, the path of said linearly polarized beam of light thereafter terminating at said object and reflecting therefrom back through said second optical means and said mirror, said second optical means dividing said beam into first and second spatially separate beams having respective directions of oscillation at right angles to each other, third optical means positioned in the path of said first and second beams between said second optical means and the image field of said object for converting said two spatially separate linearly polarized beams into two circularly polarized beams having mutually opposite senses of rotation, said two circularly polarized beams together providing a split field impinging upon an analyzer, said analyzer positioned in the path of said beams before said image field and rotating with respect to and about an axis parallel to the common incidence of said counterrotating beams, first and second detectors each positioned in a respective one of said split field and substantially coincident with said field and having produced therein electric signals, having a phase difference equal to the optical phase difference between the said partial beams, produced by said rotating analyzer.
Claim 8
Dependent Claim
14 words
The combination of claim 5 wherein said second optical means is a birefringent prism.
Claim 9
Dependent Claim
15 words
THe combination of claim 5 wherein said third optical means is a lambda /4 plate.
Claim 10
Dependent Claim
214 words
An optical interferometric system including a source of light, a reflective object surface and an image field corresponding to said object surface comprising a first beam of natural light generated by said light source, first optical means for converting said beam into first and second beams of linearly polarized light each directed at a reflecting surface, at least one of said beams striking said object surface, second optical means in the path of and responsive to said reflected first and second beams for converting said first and second beams of linearly polarized light into third and fourth beams each circularly polarized with opposite senses of rotation, a rotating analyzer positioned in the path of said third and fourth beams between said second optical means and said image field, said third and fourth beams providing a split field pattern, said analyzer rotating uniformly relative to said split field pattern to produce a first and second signal having a phase difference equal to the optical phase differences between said third and fourth beams, and first and second photodetection means positioned in respective ones of said split fields on the side of said analyzer opposite the side upon which said third and fourth beams are incident and proximate said image field for electrically detecting said phase difference.
Claim 11
Dependent Claim
214 words
An optical interferometric system including a source of light, a reflective object surface and an image field corresponding to said object surface comprising a first beam of natural light generated by said light source, first optical means for converting said beam into first and second beams of linearly polarized light each directed at a reflecting surface, at least one of said beams striking said object surface, second optical means in the path of and responsive to said reflected first and second beams for converting said first and second beams of linearly polarized light into third and fourth beams each circularly polarized with opposite senses of rotation, a rotating analyzer positioned in the path of said third and fourth beams between said second optical means and said image field, said third and fourth beams providing a split field pattern, said analyzer rotating uniformly relative to said split field pattern to produce a first and second signal having a phase difference equal to the optical phase differences between said third and fourth beams, and first and second photodetection means positioned in respective ones of said split fields on the side of said analyzer opposite the side upon which said third and fourth beams are incident and proximate said image field for electrically detecting said phase difference.
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) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |