EP0466670A2
Expired / Lapsed
EP
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System and method for optical phase change recording
Assignee: International Business Machines Corp
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Filing: 1991-06-20
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Granted: —
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Expires: 2011-06-20
Abstract
Abstract An optical phase change medium (100) comprises a substrate (102), an active layer (104) having a crystalline and a liquid state, a dielectric layer (106) and a reflective layer (108). The active layer is of a thickness which will transmit incident light. The dielectric layer is of a thickness such that light passing through the active layer is reflected by the reflective layer and destructively interferes with the incident light reflected directly off of the active layer, thereby causing the crystalline state of the active layer to absorb more light than the liquid state. The result is that the medium experiences reduced temperature during writing.
Inventors
- 👤 Martin Yu-Wen Chen
- 👤 Kurt Allan Rubin
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 03:11
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/252; G11B7/257; G11B7/004; G11B7/0055; G11B7/00557; G11B7/242; G11B7/243; G11B7/258; G11B2007/24302; G11B2007/24312; G11B2007/24316; G11B7/253; G11B7/2531; G11B7/2585; G11B7/259
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
79 words
An optical recording medium comprising: an active layer comprised of a material capable of undergoing a change between a first state and a second state, said second state having a bulk reflectivity greater than said first state, characterized by a dielectric layer overlying the active layer, said dielectric layer having a thickness such that said first state has a higher reflectivity than said second state for light incident on the medium, and a reflective layer overlying the dielectric layer.
Claim 2
Dependent Claim
19 words
The medium as claimed in claim 1 further including: a substrate located on one side of the active layer.
Claim 3
Dependent Claim
28 words
The medium as claimed in claim 1 or 2, wherein the active layer is converted from said second state to said first state by a change in temperature.
Claim 4
Independent Claim
23 words
The medium as claimed in any preceding claim, wherein the first and second states are a noncrystalline state and a crystalline state respectively.
Claim 5
Independent Claim
61 words
The medium as claimed in any preceding claim, wherein the dielectric layer overlaying the active layer is substantially transparent, and is of a thickness such that light passing through the active layer is reflected by the reflective layer and destructively interferes with light reflected off of the active layer so that said noncrystalline state reflects more light than said crystalline state.
Claim 6
Independent Claim
18 words
The medium as claimed in any preceding claim, wherein the active layer is comprised of a chalcogenide material.
Claim 7
Independent Claim
27 words
The medium as claimed in any of claims 4-6, wherein the absorption of the noncrystalline state divided by the absorption of the crystalline state is approximately 0.6.
Claim 8
Independent Claim
31 words
The medium as claimed in any preceding claim, wherein the dielectric layer thickness is such that the difference in reflectivity of said noncrystalline state and said crystalline state is a maximum.
Claim 9
Independent Claim
26 words
The medium as claimed in any preceding claim, wherein the active layer is approximately 100 Å thick and the dielectric layer is approximately 1750 Å thick.
Claim 10
Independent Claim
24 words
The medium as claimed in any preceding claim, wherein the active layer is made of (GeTe)₈₅Sn₁₅ and the dielectric layer is Made of glass.
Claim 11
Independent Claim
79 words
A method for making an optical recording media comprising the steps of: depositing an active layer onto a substrate, said active layer made of a material having a noncrystalline state and a crystalline state; depositing a dielectric layer onto said active layer, the thickness of said dielectric layer being such that said noncrystalline state of said active layer will reflect more light than said crystalline state of said active layer; and depositing a reflective layer onto said dielectric layer.
Claim 12
Dependent Claim
34 words
The method as claimed in claim 11, further including the steps of: prior to depositing an active layer, depositing an undercoat layer onto said substrate; and attaching an overcoat layer onto said reflective layer.
Claim 13
Dependent Claim
34 words
The method as claimed in claim 11 or 12, wherein said dielectric layer thickness is such that the difference in reflectivity of said noncrystalline state and said crystalline state is approximately at a maximum.
Claim 14
Dependent Claim
141 words
An optical data recording disk drive system comprising: a recording medium comprising a substrate, an active layer of a material having a noncrystalline state and a crystalline state overlying said substrate , a dielectric layer overlying said active layer, and a reflective layer overlying said dielectric layer, wherein said dielectric layer is of a thickness such that said noncrystalline state reflects more light than said crystalline state; light generating means for producing a collimated first beam of light; optical transmission means for directing said first beam of light to the medium; optical separation means for receiving said first beam of light and a reflected beam of light from the medium and separating said first beam from said reflected beam; and photodetector means for receiving said reflected beam of light from the optical separation means and generating a data signal responsive thereto.
Claim 15
Dependent Claim
21 words
The system as claimed in claim 14 further including: an inverter connected to the photodetector means for inverting said data signal.
Claim 16
Dependent Claim
30 words
The system as claimed in claim 14 or 15, wherein the optical transmission means and the optical separation means comprise a polarizing beam splitter, a quarter-wave plate and a lens.
References Cited (Backward Citations)
No citation records indexed.
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