US5684782A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Use of a laser light source as a detector via a dithering modulation
Assignee: International Business Machines Corp
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Filing: 1996-04-01
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Granted: 1997-11-04
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Expires: 2016-04-01
Abstract
Abstract Laser light is focused in an accurate manner on selected layers in a multilayer optical disk recording system by means of an analysis of output electrical signals from a dithered source which results in the production of an electrical signal which is proportional to an amount by which the parts of the system are to be relatively moved in order to achieve the desired focus on one of the layers.
Inventors
- 👤 Lawrence Jacobowitz
- 👤 Casimer Maurice DeCusatis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:05
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/125; G11B7/127; G11B7/135; G11B7/1381; G11B7/08; G11B7/09; G11B7/0901; G11B7/0904; G11B7/0908; G11B7/0917; H; H01; H01S; H01S5/00; H01S5/0014; G11B2007/0003; G11B2007/0009; G11B2007/0013; H01S3/00; H01S3/005; H01S3/0057; H01S5/0028; H01S5/005; H01S5/0057; H01S5/06; H01S5/062; H01S5/06233; H01S5/06236; H01S5/0624; H01S5/06243
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
89 words
A combined laser source and detector system comprising: a semiconductor laser light source which is capable of having its light output modulated by varying drive current applied to said semiconductor light source; means for varying the focus of light from said source, in an oscillatory manner, at a selected frequency; and means for detecting, in the range of said selected frequency, variations in current flowing through said semiconductor source, said variations being induced by laser light which is emitted from and is subsequently returned to said semiconductor light source.
Claim 2
Dependent Claim
89 words
A combined laser source and detector system comprising: a semiconductor laser light source which is capable of having its light output modulated by varying drive current applied to said semiconductor light source; means for varying the focus of light from said source, in an oscillatory manner, at a selected frequency; and means for detecting, in the range of said selected frequency, variations in current flowing through said semiconductor source, said variations being induced by laser light which is emitted from and is subsequently returned to said semiconductor light source.
Claim 3
Dependent Claim
51 words
The system of claim 1 wherein said means for detection comprises a resistive means through which said current passes and a frequency filter means which is coupled to voltage signals appearing across said resistive means and which is capable of selectively passing signals in the same frequency range as said variations.
Claim 4
Dependent Claim
23 words
The system of claim 1 further including reflective target means which is positioned to return light from said source back to said source.
Claim 5
Dependent Claim
12 words
The system of claim 3 in which said reflective target is rotating.
Claim 6
Dependent Claim
13 words
The system of claim 3 in which said target is a compact disk.
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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) | 2000-11-03 | 2001-05-05 | 2001-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-11-03 | 2005-05-05 | 2005-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-11-03 | 2009-05-05 | 2009-11-04 | $7700.00 | Window Closed / Lapsed |