US5748598A
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Apparatus and methods for reading multilayer storage media using short coherence length sources
Assignee: Massachusetts Institute of Technology
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Filing: 1995-12-22
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Granted: 1998-05-05
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Expires: 2015-12-22
Abstract
Abstract Apparatus and methods for reading multilayer optical data storage media are described. The apparatus includes a short coherence length light source and an optical system. The optical system focuses the light from the source onto the layers of the storage media. The coherence length of the source is less than 100 microns or less than the spacing between the layers. The Rayleigh range within the storage media may also be less than the spacing between the layers. The apparatus may include a detector for measuring alterations in light reflected from each layer of the storage media caused by data. The source may be any short coherence length source including superluminescent diodes, mode locked lasers, multi-longitudinal mode laser diode, or rare earth doped amplified spontaneous emission sources.
Inventors
- 👤 Eric A. Swanson
- 👤 Stephen R. Chinn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:29
CPC Classifications
A; A61; A61B; A61B1/00; A61B1/00163; A61B1/00174; A61B1/00183; A61B5/00; A61B5/0059; A61B5/0062; A61B5/0066; B; B82; B82Y; B82Y15/00; G; G01; G01B; G01B11/00; G01B11/24; G01B11/2441; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/4795; G02; G02B; G02B27/00; G02B27/42; G02B27/4233; G02B27/4238; G02B5/00; G02B5/18; G02B5/1828; G11; G11B; G11B7/00; G11B7/004; G11B7/005; G11B7/12; G11B7/125; G11B7/127; A61B5/44; A61B5/441; G11B2007/0003; G11B2007/0009; G11B2007/0013; G11B7/24; H; H01; H01S; H01S5/00; H01S5/10; H01S5/14; H01S5/141
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
102 words
An apparatus for reading data, comprising: a) a source of light having a coherence length L c ; and b) an optical system focusing said light from said source of light onto a preselected layer of an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L, wherein said spacing L is greater than a Rayleigh range L r of the optical medium and the optical system thereby substantially reducing coherence between light reflecting from the preselected layer and light reflecting from each other of said at least two layers.
Claim 2
Independent Claim
102 words
An apparatus for reading data, comprising: a) a source of light having a coherence length L c ; and b) an optical system focusing said light from said source of light onto a preselected layer of an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L, wherein said spacing L is greater than a Rayleigh range L r of the optical medium and the optical system thereby substantially reducing coherence between light reflecting from the preselected layer and light reflecting from each other of said at least two layers.
Claim 3
Dependent Claim
14 words
The apparatus of claim 1 wherein the data on each layer is binary data.
Claim 4
Dependent Claim
16 words
The apparatus of claim 1 wherein said coherence length Lc is less than substantially 50 microns.
Claim 5
Dependent Claim
16 words
The apparatus of claim 1 wherein said coherence length Lc is less than said spacing L.
Claim 6
Dependent Claim
20 words
The apparatus of claim 1 wherein said spacing L is less than ten times the Rayleigh range L r .
Claim 7
Dependent Claim
21 words
The apparatus of claim 1 wherein said spacing L is less than one hundred times the Rayleigh range L r .
Claim 8
Dependent Claim
31 words
The apparatus of claim 1 further comprising a detector for measuring alterations in said light reflected from each layer of said at least two layers which are caused by said data.
Claim 9
Dependent Claim
14 words
The apparatus of claim 7 wherein the detector detects a substantially single spatial mode.
Claim 10
Dependent Claim
27 words
The apparatus of claim 1 wherein said optical system selectively focuses light from said source of light onto one of said at least two layers containing data.
Claim 11
Dependent Claim
14 words
The apparatus of claim 1 wherein the source of light is a superluminescent diode.
Claim 12
Dependent Claim
15 words
The apparatus of claim 1 wherein the source of light is a mode locked laser.
Claim 13
Dependent Claim
19 words
The apparatus of claim 1 wherein the source of light is a rare earth doped amplified spontaneous emission source.
Claim 14
Dependent Claim
16 words
The apparatus of claim 1 wherein the source of light is a continuous wave laser diode.
Claim 15
Dependent Claim
14 words
The apparatus of claim 1 wherein the optical system forms a single spatial mode.
Claim 16
Independent Claim
93 words
An apparatus for reading data, comprising: a) an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L; b) a source of light having a coherence length L c less than said spacing L; and c) an optical system focusing said light from said source of light onto a preselected layer of interest in said optical medium, wherein coherence of light reflecting from the preselected layer and light reflecting from each other of said at least two layers is substantially reduced.
Claim 17
Independent Claim
93 words
An apparatus for reading data, comprising: a) an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L; b) a source of light having a coherence length L c less than said spacing L; and c) an optical system focusing said light from said source of light onto a preselected layer of interest in said optical medium, wherein coherence of light reflecting from the preselected layer and light reflecting from each other of said at least two layers is substantially reduced.
Claim 18
Dependent Claim
31 words
The apparatus of claim 15 further comprising a detector for measuring alterations in said light reflected from each layer of said at least two layers which are caused by said data.
Claim 19
Dependent Claim
14 words
The apparatus of claim 15 wherein the source of light is a superluminescent diode.
Claim 20
Dependent Claim
15 words
The apparatus of claim 15 wherein the source of light is a mode locked laser.
Claim 21
Dependent Claim
19 words
The apparatus of claim 15 wherein the source of light is a rare earth doped amplified spontaneous emission source.
Claim 22
Independent Claim
93 words
A method of reading data, comprising: a) providing a source of light having a coherence length L c ; and b) focusing said light from said source of light onto a preselected layer of an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L, wherein said coherence length Lc is less than said spacing L so that coherence of light reflecting from the preselected layer and light reflecting from each other of said at least two layers is substantially reduced.
Claim 23
Independent Claim
93 words
A method of reading data, comprising: a) providing a source of light having a coherence length L c ; and b) focusing said light from said source of light onto a preselected layer of an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L, wherein said coherence length Lc is less than said spacing L so that coherence of light reflecting from the preselected layer and light reflecting from each other of said at least two layers is substantially reduced.
Claim 24
Dependent Claim
16 words
The apparatus of claim 20 wherein said coherence length Lc is less than said spacing L.
Claim 25
Dependent Claim
16 words
The apparatus of claim 20 wherein said coherence length Lc is less than substantially 50 microns.
Claim 26
Dependent Claim
31 words
The method of claim 20 further comprising a step of detecting alterations in said light reflected from each layer of said at least two layers which are caused by said data.
Claim 27
Independent Claim
91 words
A method for reading data, comprising: a) providing an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L; b) providing a source of light having a coherence length L c less than said spacing L; and c) focusing said light from said source of light onto a preselected layer of said optical medium so that coherence of light reflecting from the preselected layer and light reflecting from each other of said at least two layers is substantially reduced.
Claim 28
Independent Claim
91 words
A method for reading data, comprising: a) providing an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L; b) providing a source of light having a coherence length L c less than said spacing L; and c) focusing said light from said source of light onto a preselected layer of said optical medium so that coherence of light reflecting from the preselected layer and light reflecting from each other of said at least two layers is substantially reduced.
Claim 29
Dependent Claim
31 words
The method of claim 24 further comprising a step of detecting alterations in said light reflected from each layer of said at least two layers which are caused by said data.
Claim 30
Independent Claim
79 words
An apparatus for reading data, comprising: a) a source of light having a coherence length L c ; and b) an optical system focusing said light from said source of light onto a preselected layer of an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L, wherein said spacing L is greater than a Rayleigh range L r of the optical medium and the optical system.
Claim 31
Independent Claim
79 words
An apparatus for reading data, comprising: a) a source of light having a coherence length L c ; and b) an optical system focusing said light from said source of light onto a preselected layer of an optical medium comprising at least two layers, each layer of said at least two layers containing data and having a spacing L, wherein said spacing L is greater than a Rayleigh range L r of the optical medium and the optical system.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2001-05-04 | 2001-11-03 | 2002-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-04 | 2005-11-03 | 2006-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-04 | 2009-11-03 | 2010-05-05 | $7700.00 | Window Closed / Lapsed |