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US4595261A
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Phase retardation element and prism for use in an optical data storage system
Assignee: International Business Machines Corp
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Filing: 1983-10-13
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Granted: 1986-06-17
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Expires: 2003-10-13
Abstract
Abstract A phase retardation element, for use in an optical data storage system, which provides a 90° phase difference between two perpendicular polarized components of an incident wave with a single internal reflection from a surface coated with a thin film of dielectric or metal material.
Inventors
- 👤 Holger J. Baasch
- 👤 Douglas S. Goodman
- 👤 Francis S. Luecke
- 👤 Ronald L. Soderstrom
- 👤 Eberhard A. Spiller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 04:19
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1365; G02; G02B; G02B5/00; G02B5/30; G02B5/3083
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
122 words
An optical element for producing a phase difference of 90° between two perpendicular polarized components of a beam of radiation internally reflected in said element comprising: an optical member formed of a material capable of supporting the propagation of a beam of radiation having a wavelength within a wavelength range extending from 0.74 μm to 0.98 μm; a plane surface portion of said member; a plurality of thin film coatings of dielectric materials layered on said plane surface portion; said thin film coatings being of materials and thicknesses to produce throughout said wavelength range of substantially constant phase difference of 90° between two perpendicular polarized components of said beam of radiation when said beam is internally reflected at said plane surface portion.
Claim 2
Dependent Claim
122 words
An optical element for producing a phase difference of 90° between two perpendicular polarized components of a beam of radiation internally reflected in said element comprising: an optical member formed of a material capable of supporting the propagation of a beam of radiation having a wavelength within a wavelength range extending from 0.74 μm to 0.98 μm; a plane surface portion of said member; a plurality of thin film coatings of dielectric materials layered on said plane surface portion; said thin film coatings being of materials and thicknesses to produce throughout said wavelength range of substantially constant phase difference of 90° between two perpendicular polarized components of said beam of radiation when said beam is internally reflected at said plane surface portion.
Claim 3
Dependent Claim
24 words
An optical element according to claim 1 wherein said member is a prism and said plane surface portion is one face of said prism.
Claim 4
Dependent Claim
37 words
The optical element of claim 1 wherein: said plurality of thin film coatings comprises three coatings having indices of refraction of substantially 2.3, 1.7 and 1.5 and having normalized thicknesses of substantially 0.045, 0.111 and 0.386 respectively.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-06-16 | 1989-12-16 | 1990-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-16 | 1993-12-16 | 1994-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-16 | 1997-12-16 | 1998-06-17 | $7700.00 | Window Closed / Lapsed |