US4523848A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polariscope
Assignee: BTG International Ltd
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Filing: 1982-09-24
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Granted: 1985-06-18
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Expires: 2002-09-24
Abstract
Abstract In a polariscope including first and second quarter wave plates arranged one on either side of a sample under test, first and second liquid crystal devices are provided adjacent the quarter wave plates and can be switched between two optical conditions to alter the polariscope between a plane polarized and a circularly polarized mode.
Inventors
- 👤 Barry Gorman
- 👤 Edwin J. Hearn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:48
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/1313; G01; G01L; G01L1/00; G01L1/24; G01L1/241; G01N; G01N21/00; G01N21/17; G01N21/21; G01N21/23; G01N2021/216
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
126 words
A polariscope comprises means to provide an input beam of polarised light; first liquid crystal means which in a first state allows direct passage of the polarised input beam and in a second state applies a 45° rotation to the polarised input beam; a first quarter wave plate; sample location means; a second quarter wave plate; second liquid crystal means which in a first state allows passage of light polarised perpendicular to the polarisation axis of the input beam and in a second state applies a 45° rotation to said light; second polarising means parallel to or crossed with respect to the first polarising means; and switch means to cause the first and second liquid crystal means each to change between their first and second states.
Claim 2
Dependent Claim
126 words
A polariscope comprises means to provide an input beam of polarised light; first liquid crystal means which in a first state allows direct passage of the polarised input beam and in a second state applies a 45° rotation to the polarised input beam; a first quarter wave plate; sample location means; a second quarter wave plate; second liquid crystal means which in a first state allows passage of light polarised perpendicular to the polarisation axis of the input beam and in a second state applies a 45° rotation to said light; second polarising means parallel to or crossed with respect to the first polarising means; and switch means to cause the first and second liquid crystal means each to change between their first and second states.
Claim 3
Dependent Claim
35 words
A polariscope according to claim 1 in which the direction of polarisation of the second polarising means can be rotated with respect to the polarised input beam to angles intermediate the parallel and crossed positions.
Claim 4
Dependent Claim
17 words
A polariscope according to claim 2 in which the second polarising means is a liquid crystal device.
Claim 5
Dependent Claim
20 words
A polariscope according to claim 1 in which the components are provided in axial alignment to provide a transmission polariscope.
Claim 6
Dependent Claim
33 words
A polariscope according to claim 1 arranged so that light reflected by a sample in the sample location means is received by the second quarter wave plate, whereby a reflection polariscope is provided.
Claim 7
Dependent Claim
20 words
A polariscope according to claim 1 in which at least one quarter wave plate also comprises a liquid crystal device.
References Cited (Backward Citations)
GB1372868A
Cited
GB1390925A
Cited
GB1469638A
Cited
US3902805A
Cited
GB1496499A
Cited
GB1448520A
Cited
GB1477478A
Cited
GB1506570A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-17 | 1988-12-17 | 1989-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-17 | 1992-12-17 | 1993-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-17 | 1996-12-17 | 1997-06-18 | $7700.00 | Window Closed / Lapsed |