US4243323A
Expired / Lapsed
US
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Interferometer
Assignee: National Aeronautics and Space Administration
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Filing: 1978-11-30
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Granted: 1981-01-06
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Expires: 1998-11-30
Abstract
Abstract An interferometer of relatively simple design which is tilt compensated, and which facilitates adjustment of the path lengths of split light beams. The interferometer includes a pair of plate-like elements with a dielectric coating and an oil film between them, that forms a beamsplitter interface, and with a pair of reflector surfaces at the ends of the plates. A pair of retroreflectors are positioned so that each split beam component is directed by a retroreflector onto one of the reflector surfaces and is then returned to the beamsplitter interface, so that the reflector surfaces tilt in a direction and amount that compensates for tilting of the beamsplitter interface. The oil film is less than about 20 microinches thick, to pass approximately equal amounts of all wavelengths longer than the film thickness, and yet to provide a sliding surface that enables one plate to shift relative to the other. The plate-like elements are slightly tapered to avoid channeling effects.
Inventors
- 👤 with respect to an invention of Frosch Robert A. Administrator of the National Aeronautics and Space Administration
- 👤 James B. Breckinridge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 02:05
CPC Classifications
G; G01; G01J; G01J9/00; G01J9/02
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
92 words
An interferometer comprising: a pair of substantially plate-like optical elements having facewise adjacent splitter surfaces forming a beamsplitter interface, each of said elements having an edge portion forming a reflector surface angled from said splitter surfaces; a pair of retroreflector means positioned to direct the components of a light beam split at said beamsplitter interface, onto corresponding reflector surfaces, and to direct the components reflected from said reflector surfaces back to said beamsplitter interface; and a light detector positioned to receive beam components which have been directed back to said beamsplitter interface.
Claim 2
Dependent Claim
92 words
An interferometer comprising: a pair of substantially plate-like optical elements having facewise adjacent splitter surfaces forming a beamsplitter interface, each of said elements having an edge portion forming a reflector surface angled from said splitter surfaces; a pair of retroreflector means positioned to direct the components of a light beam split at said beamsplitter interface, onto corresponding reflector surfaces, and to direct the components reflected from said reflector surfaces back to said beamsplitter interface; and a light detector positioned to receive beam components which have been directed back to said beamsplitter interface.
Claim 3
Dependent Claim
40 words
The interferometer described in claim 1 wherein: each of said optical elements is wedge shaped, with each element having two flat faces extending in planes slightly angled from parallelism, one of said faces forming one of said facewise adjacent surfaces.
Claim 4
Dependent Claim
27 words
The interferometer described in claim 1 wherein: each of said reflector surfaces extends at an obtuse angle with respect to the splitter surface of the same element.
Claim 5
Dependent Claim
128 words
An interferometer comprising: an optical device which includes first and second optical elements having flat facewise adjacent surfaces forming a beamsplitter interface for dividing an initial beam directed along an initial path into a pair of beam components initially passing along a pair of initial component paths, each of said optical elements also forming a reflector surface offset from one of said initial component paths, and said elements being slidable with respect to one another along said facewise adjacent surfaces; first and second retroreflectors, each positioned to direct light moving along one of the initial component paths to one of said reflector surfaces for reflection therefrom back through the retroreflector and to the beamsplitter interface to combine said components; and detector means responsive to said combined beam components.
Claim 6
Dependent Claim
128 words
An interferometer comprising: an optical device which includes first and second optical elements having flat facewise adjacent surfaces forming a beamsplitter interface for dividing an initial beam directed along an initial path into a pair of beam components initially passing along a pair of initial component paths, each of said optical elements also forming a reflector surface offset from one of said initial component paths, and said elements being slidable with respect to one another along said facewise adjacent surfaces; first and second retroreflectors, each positioned to direct light moving along one of the initial component paths to one of said reflector surfaces for reflection therefrom back through the retroreflector and to the beamsplitter interface to combine said components; and detector means responsive to said combined beam components.
Claim 7
Dependent Claim
140 words
An interferometer comprising: an optical device which includes two largely platelike elements having flat adjacent surfaces forming a beamsplitter interface for dividing an initial beam directed along an initial path into a pair of beam components initially passing through different elements along a pair of initial component paths, said optical device also forming a pair of reflector surfaces offset from said initial component paths; first and second retroreflectors, each positioned to direct light moving along one of the initial component paths to one of said reflector surfaces for reflection therefrom back through the retroreflector and to the beamsplitter interface to combine said components; and detector means responsive to said combined beam components; each of said plate-like elements having a face opposite said beamsplitter interface, which is angled from parallelism with the interface surface of the element by less than 30°.
Claim 8
Dependent Claim
140 words
An interferometer comprising: an optical device which includes two largely platelike elements having flat adjacent surfaces forming a beamsplitter interface for dividing an initial beam directed along an initial path into a pair of beam components initially passing through different elements along a pair of initial component paths, said optical device also forming a pair of reflector surfaces offset from said initial component paths; first and second retroreflectors, each positioned to direct light moving along one of the initial component paths to one of said reflector surfaces for reflection therefrom back through the retroreflector and to the beamsplitter interface to combine said components; and detector means responsive to said combined beam components; each of said plate-like elements having a face opposite said beamsplitter interface, which is angled from parallelism with the interface surface of the element by less than 30°.
Claim 9
Dependent Claim
32 words
The interferometer described in claim 5 wherein: said elements are slidable relative to one another along said beamsplitter interface, whereby to enable adjustment of the beam component path lengths within the elements.
Claim 10
Dependent Claim
152 words
An interferometer comprising: an optical device forming a beamsplitter interface for dividing an initial beam directed along an initial path into a pair of beam components initially passing along a pair of initial component paths, said optical device also forming a pair of reflector surfaces offset from said initial component paths; first and second retroreflectors, each positioned to direct light moving along one of the initial component paths to one of said reflector surfaces for reflection therefrom back through the retroreflector and to the beamsplitter interface to combine said components; and detector means responsive to said combined beam components; said optical device including a pair of optical elements having adjacent surfaces lying at said beamsplitter interface, and a thin fluid film between said adjacent surfaces, said film having a thickness less than about twenty microinches, whereby to pass high proportions of visible light wave lengths which are shorter than the film thickness.
Claim 11
Dependent Claim
152 words
An interferometer comprising: an optical device forming a beamsplitter interface for dividing an initial beam directed along an initial path into a pair of beam components initially passing along a pair of initial component paths, said optical device also forming a pair of reflector surfaces offset from said initial component paths; first and second retroreflectors, each positioned to direct light moving along one of the initial component paths to one of said reflector surfaces for reflection therefrom back through the retroreflector and to the beamsplitter interface to combine said components; and detector means responsive to said combined beam components; said optical device including a pair of optical elements having adjacent surfaces lying at said beamsplitter interface, and a thin fluid film between said adjacent surfaces, said film having a thickness less than about twenty microinches, whereby to pass high proportions of visible light wave lengths which are shorter than the film thickness.
Claim 12
Dependent Claim
88 words
In an interferometer which includes a detector for detecting the interference pattern formed by combined light beam components, the improvement of a beam splitter device comprising: first and second optical elements having facewise adjacent surfaces; and a film of liquid lying substantially between and in contact with said surfaces, and defining the separation between said element surfaces; said liquid film having a thickness less than 20 microinches, whereby to pass a largely uniformly high proportion of light of a range of wavelengths that are directed at said film.
Claim 13
Dependent Claim
88 words
In an interferometer which includes a detector for detecting the interference pattern formed by combined light beam components, the improvement of a beam splitter device comprising: first and second optical elements having facewise adjacent surfaces; and a film of liquid lying substantially between and in contact with said surfaces, and defining the separation between said element surfaces; said liquid film having a thickness less than 20 microinches, whereby to pass a largely uniformly high proportion of light of a range of wavelengths that are directed at said film.
Claim 14
Dependent Claim
30 words
The improvement described in claim 8 wherein: at least one of said optical elements has a dielectric coating at its surface which lies facewise adjacent to the other element surface.
Claim 15
Dependent Claim
79 words
In an interferometer which includes a detector for detecting the interference pattern formed by combined light beam components, the improvement of a beam splitter device comprising: first and second optical elements having facewise adjacent surfaces; a film of liquid lying substantially between and in contact with said surfaces, and defining the separation between said element surfaces; and an actuator coupled to at least one of said elements to shift it relative to the other element along said liquid film.
Claim 16
Dependent Claim
79 words
In an interferometer which includes a detector for detecting the interference pattern formed by combined light beam components, the improvement of a beam splitter device comprising: first and second optical elements having facewise adjacent surfaces; a film of liquid lying substantially between and in contact with said surfaces, and defining the separation between said element surfaces; and an actuator coupled to at least one of said elements to shift it relative to the other element along said liquid film.
Claim 17
Dependent Claim
103 words
In an interferometer which includes a detector for detecting the interference pattern formed by combined light beam components, the improvement of a beam splitter device comprising: first and second optical elements having facewise adjacent surfaces; and a film of liquid lying substantially between and in contact with said surfaces, and defining the separation between said element surfaces; each of said elements being largely in the form of a plate with a pair of substantially flat spaced surfaces, but the pair of surfaces of at least one element lying in planes angled on the order of magnitude of 1° from parallelism with each other.
Claim 18
Dependent Claim
103 words
In an interferometer which includes a detector for detecting the interference pattern formed by combined light beam components, the improvement of a beam splitter device comprising: first and second optical elements having facewise adjacent surfaces; and a film of liquid lying substantially between and in contact with said surfaces, and defining the separation between said element surfaces; each of said elements being largely in the form of a plate with a pair of substantially flat spaced surfaces, but the pair of surfaces of at least one element lying in planes angled on the order of magnitude of 1° from parallelism with each other.
Claim 19
Dependent Claim
109 words
In an interferometer which includes a detector for detecting the interference pattern formed by combined light beam components, the improvement of a beam splitter device comprising: first and second optical elements having facewise adjacent surfaces, each element also having a reflector surface angled 45° from said adjacent surfaces; a film of liquid lying substantially between and in contact with said surfaces, and defining the separation between said element surfaces; and a pair of retroreflectors, each positioned to direct a light beam component emerging from one of said optical elements adjacent surfaces at a 45° angle therefrom, onto one of said reflector surfaces for reflection back to said element surface.
Claim 20
Dependent Claim
109 words
In an interferometer which includes a detector for detecting the interference pattern formed by combined light beam components, the improvement of a beam splitter device comprising: first and second optical elements having facewise adjacent surfaces, each element also having a reflector surface angled 45° from said adjacent surfaces; a film of liquid lying substantially between and in contact with said surfaces, and defining the separation between said element surfaces; and a pair of retroreflectors, each positioned to direct a light beam component emerging from one of said optical elements adjacent surfaces at a 45° angle therefrom, onto one of said reflector surfaces for reflection back to said element surface.
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) | 1984-01-06 | 1984-07-07 | 1985-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-06 | 1988-07-07 | 1989-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-06 | 1992-07-07 | 1993-01-06 | $7700.00 | Window Closed / Lapsed |