US3819939A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital light deflector
Assignee: US Philips Corp
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Filing: 1972-09-13
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Granted: 1974-06-25
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Expires: 1992-09-13
Abstract
Abstract A digital light deflector is described which comprises a plurality of deflector stages which each include a polarization switch and a birefringent element. It is shown that the stray light can be determined by introducing, behind the last deflector stage, an additional polarization switch and a polarization separating element and also a radiation-sensitive detector which converts the stray light into an electric signal for controlling the switching voltage of the polarization switches.
Inventors
- 👤 M Rahlff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:37
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/29; G02F1/31
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
147 words
A drift compensator for a digital light deflector of the type wherein a beam of radiation passes through a plurality of energizable radiation deflection stages each including a polarization switch activated by a switching voltage and a birefringent element, the compensator comprising an additional polarization switch in the path of the deflected radiation from the plurality of deflection stages and operable in response to an odd number of radiation deflection stages being energized, a polarization separating element in the path of the radiation passing through the additional polarization switch for spatially separating the portion of the radiation due to stray light from a signal light portion of the beam, and radiation-sensitive detector in the path of the stray light radiation from the birefringeNt element for providing an electrical signal suitable for controlling the magnitude of the switching voltage of the polarization switches in the digital light deflector.
Claim 2
Dependent Claim
147 words
A drift compensator for a digital light deflector of the type wherein a beam of radiation passes through a plurality of energizable radiation deflection stages each including a polarization switch activated by a switching voltage and a birefringent element, the compensator comprising an additional polarization switch in the path of the deflected radiation from the plurality of deflection stages and operable in response to an odd number of radiation deflection stages being energized, a polarization separating element in the path of the radiation passing through the additional polarization switch for spatially separating the portion of the radiation due to stray light from a signal light portion of the beam, and radiation-sensitive detector in the path of the stray light radiation from the birefringeNt element for providing an electrical signal suitable for controlling the magnitude of the switching voltage of the polarization switches in the digital light deflector.
Claim 3
Dependent Claim
18 words
Digital light deflector as claimed in claim 1, wherein the polarization-separating element is a direct-vision Glan-Thompson polarizing prism.
Claim 4
Dependent Claim
17 words
Digital light deflector as claimed in claim 1, wherein the polarization-separating element is a birefringent single prism.
Claim 5
Dependent Claim
19 words
Digital light deflector as claimed in claim 3, wherein the birefringent single prism is combined with a compensating prism.
Claim 6
Dependent Claim
57 words
Digital light deflector as claimed in claim 1, wherein the polarization separating element is a birefringent parallel plate which is oriented so that one of the beams of stray light and signal light enters the plate at an angle greater than the critical angle for total reflection and the other emerges from the parallel plate by refraction.
Claim 7
Dependent Claim
37 words
Digital light deflector as claimed in claim 1 which comprises a plurality of units which each include a plurality of deflector stages, wherein each unit is provided with an additional polarization switch and a polarization separating element.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |