Patent US4309109A successfully refreshed from Google Patents.
US4309109A
Expired / Lapsed
US
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Pulsed interferometric remote gauge
Assignee: United States Department of the Navy
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Filing: 1972-05-25
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Granted: 1982-01-05
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Expires: 1992-05-25
Abstract
Abstract The invention comprises a method and means for measuring the separation been two optical surfaces. A short-coherence-length laser pulse is projected upon two optical surfaces separated by a distance, d. The reflected, coincident beams are directed into a Michelson interferometer in which one plane mirror is replaced by a stepped mirror. The beams reflected from the two mirrors are directed onto a film where they form interference images. A formula using the number of channels, n, between successive interference fringes and the step width of the stepped mirror is used to calculate d.
Inventors
- 👤 Jerry A. Blodgett
- 👤 Raymond A. Patten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:57
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/02015; G01B9/02027; G01B9/02028; G01B11/00; G01B11/14; G01B9/02055; G01B9/02056; G01B9/02057; G01B9/02062; G01B9/02064; G01B9/02065
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
136 words
Apparatus for measuring the separation distance between two light-reflecting surfaces comprising, in combination: means for irradiating a pair of spaced, light-reflecting surfaces with a laser pulse; interferometer means comprising an interferometer of the Michelson type having stepped mirror means in place of one of the two usual plane mirrors therein, said interferometer being positioned to receive the light reflected from said two light-reflecting surfaces; and means for deriving the interference pattern produced by said interferometer, each step of said stepped mirror having a step height δ, and a step depth Δ, which are equal, the interference pattern containing a series of columns some of which have interference fringe regions therein, the number of columns between the corresponding edges of two successive interference regions being designated n, and the separation distance being obtained from the formula d=nΔ
Claim 2
Dependent Claim
136 words
Apparatus for measuring the separation distance between two light-reflecting surfaces comprising, in combination: means for irradiating a pair of spaced, light-reflecting surfaces with a laser pulse; interferometer means comprising an interferometer of the Michelson type having stepped mirror means in place of one of the two usual plane mirrors therein, said interferometer being positioned to receive the light reflected from said two light-reflecting surfaces; and means for deriving the interference pattern produced by said interferometer, each step of said stepped mirror having a step height δ, and a step depth Δ, which are equal, the interference pattern containing a series of columns some of which have interference fringe regions therein, the number of columns between the corresponding edges of two successive interference regions being designated n, and the separation distance being obtained from the formula d=nΔ
Claim 3
Dependent Claim
19 words
Apparatus as in claim 1, wherein said light-reflecting surfaces are curved, the optical axes of said surfaces being coincident.
Claim 4
Dependent Claim
15 words
Apparatus as in claim 1, said means for deriving the interference pattern being photographic film.
Claim 5
Dependent Claim
23 words
Apparatus as in claim 3, the light from the laser lying in the infrared spectrum and said film being sensitive to infrared radiations.
References Cited (Backward Citations)
US3127465A
Cited
US3319515A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-01-04 | 1985-07-06 | 1986-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-01-04 | 1989-07-06 | 1990-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-01-04 | 1993-07-06 | 1994-01-05 | $7700.00 | Window Closed / Lapsed |