Patent US4884044A successfully refreshed from Google Patents.
US4884044A
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US
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Optical modulators
Assignee: Ferranti International PLC
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Filing: 1988-08-23
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Granted: 1989-11-28
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Expires: 2008-08-23
Abstract
Abstract An optical modulator comprises a crystal (15) of material exhibiting the pyroelectric effect, and charge-dissipating means for dissipating any charge built up on the optical faces of the prism. The charge-dissipating means may comprise point electrodes (30) positioned adjacent to the optical faces (21) of the crystal and connected to an alternating-current high-voltage power supply (31). The electrodes produce charged ions which neutralize any charge on the optical faces of the crystal. The crystal may be used as the Q-switch in a laser.
Inventors
- 👤 Peter J. Heywood
- 👤 Richard A. Eggleston
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 03:39
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/11; H01S3/1123; H01S3/115; G; G02; G02F; G02F1/00; G02F1/01; G02F1/03; G02F1/0305; G02F2203/00; G02F2203/21
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
77 words
An optical modulator of the Q-switch type comprising: a crystal of a material which exhibits the pyroelectric effect and having two opposed optical faces through which laser radiation may pass along a path; means to apply an electric field to the crystal ransverse to said path in order to switch said modulator; and charge-dissipating means for dissipating any static electric charge built up on the two opposed optical faces of the crystal due to the pyroelectric effect.
Claim 2
Dependent Claim
77 words
An optical modulator of the Q-switch type comprising: a crystal of a material which exhibits the pyroelectric effect and having two opposed optical faces through which laser radiation may pass along a path; means to apply an electric field to the crystal ransverse to said path in order to switch said modulator; and charge-dissipating means for dissipating any static electric charge built up on the two opposed optical faces of the crystal due to the pyroelectric effect.
Claim 3
Dependent Claim
35 words
A modulator as claimed in claim 1 which includes ionising means located adjacent to the optical faces of the crystal and operable to generate ions of opposite polarity to the charge on said optical face.
Claim 4
Dependent Claim
22 words
A modulator as claimed in claim 2 in which the ionising means comprise a point electrode connected to a high-voltage power supply.
Claim 5
Dependent Claim
23 words
A modulator as claimed in claim 3 in which the high-voltage power supply generates an alternating voltage for application to the point electrodes.
Claim 6
Dependent Claim
16 words
A modulator as claimed in claim 2 in which the ionising means comprise a spark gap.
Claim 7
Dependent Claim
25 words
A modulator as claimed in claim 2 in which the ionising means comprise a radioactive source capable of emitting ionising radiation towards said optical faces.
Claim 8
Dependent Claim
26 words
A modulator as claimed in claim 1 in which the optical faces of the crystal are provided with a layer of electrically-conducting material connected to ground.
Claim 9
Dependent Claim
28 words
A modulator as claimed in claim 1 in which each optical end face is provided with an electrically-conductive wiper movable across the said face and connected to ground.
Claim 10
Dependent Claim
15 words
A modulator as claimed in claim 1 which forms the Q-switch of a Q-switched laser.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-11-27 | 1993-05-29 | 1993-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-27 | 1997-05-29 | 1997-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-27 | 2001-05-29 | 2001-11-28 | $7700.00 | Window Closed / Lapsed |