Patent US4904086A successfully refreshed from Google Patents.
US4904086A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light alignment detection device
Assignee: Matra Marconi Space UK Ltd
•
Filing: 1989-01-05
•
Granted: 1990-02-27
•
Expires: 2009-01-05
Abstract
Abstract An optical alignment detector uses a Fresnel bi-prism (12) on the base of which an incoming beam of light is focussed. When the beam is in alignment, it strikes the base substantially normally and is brought to a focus adjacent a ridge (13) of the bi-prism (12). To cope with a second axis of alignment, a second bi-prism (14) having a ridge (15) is placed beneath the first, with the two ridges (13,15) arranged orthogonally so as to produce four possible pupil entrance images which can be received by four photodetectors (17,18,19,20).
Inventors
- 👤 Paul E. G. Cope
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 00:51
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/26; G01B11/27; G01B11/272
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
86 words
An optical alignment detector device comprising: means for focussing an incoming beam of light, a Fresnel bi-prism mounted with its base towards the focussing means such that when the beam is in alignment with the optical axis of the focussing means the beam strikes the base substantially normally and is brought to a focus adjacent the ridge of bi-prism, and a pair of photodetectors disposed to receive light transmitted through the prism and located on either side of the plane containing the ridge of the bi-prism.
Claim 2
Dependent Claim
86 words
An optical alignment detector device comprising: means for focussing an incoming beam of light, a Fresnel bi-prism mounted with its base towards the focussing means such that when the beam is in alignment with the optical axis of the focussing means the beam strikes the base substantially normally and is brought to a focus adjacent the ridge of bi-prism, and a pair of photodetectors disposed to receive light transmitted through the prism and located on either side of the plane containing the ridge of the bi-prism.
Claim 3
Dependent Claim
64 words
A device as claimed is claim 1 wherein there is a second bi-prism mounted beneath the first prism, the second bi-prism having the length of its ridge disposed orthogonally with respect to the ridge of the first bi-prism and being inverted with respect to the first bi-prism, the arrangement being such that an out-of-alignment input beam generates one to four displaced entrance pupil images.
Claim 4
Dependent Claim
60 words
A device as claimed in claim 2 wherein a field lens is mounted in the optical path after the two bi-prisms so that the or each entrance pupil image lies in its focal plane, the arrangement further including four photodetectors mounted so that each one covers one of the four possible entrance pupil images as focussed by the field lens.
Claim 5
Dependent Claim
22 words
A device as claimed in claim 1 wherein the means for focusing an incoming beam of light comprises a simple compound telescope.
Claim 6
Dependent Claim
17 words
A device as claimed in claim 4 wherein the telescope has a numerical aperture of approximately F/16.
References Cited (Backward Citations)
US3133200A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-02-26 | 1993-08-28 | 1994-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-26 | 1997-08-28 | 1998-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-26 | 2001-08-28 | 2002-02-27 | $7700.00 | Window Closed / Lapsed |