# US 5,700,539 A · Thin film and interferometric optical disk media and mass production method for fabricating such and multi-layer CDS

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- Number: US 5,700,539 A
- Document ID: US5700539A
- Status: Granted
- Kind: A
- Application number: 08/644,615
- Filed: 1996-05-01
- Granted: 1997-12-23
- Earliest claimed: 1995-08-14
- Inventors: Gilbert H. Hong
- Web page: https://patentgrep.com/patent/US5700539A

## CPC

- B29D 17/005: {Producing optically read record carriers, e.g. optical discs}
- G11B 7/24: Record carriers characterised by shape, structure or physical properties, or by the selection of the material (characterised by the arrangement of information on the carrier G11B7/007)
- G11B 7/263: {Preparing and using a stamper, e.g. pressing or injection molding substrates (production of optical record carriers, e.g. optical discs B29D17/005)}
- G11B 7/0051: {involving phase depth effects}
- G11B 7/26: Apparatus or processes specially adapted for the manufacture of record carriers
- Y10S 425/81: Sound record
- Y10S 428/913: Material designed to be responsive to temperature, light, moisture
- Y10S 430/146: Laser beam
- Y10T 428/21: Circular sheet or circular blank
- Y10T 428/31678: Of metal
- B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00)
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An optical disk records digital information in optically-reflective layers that each vary in thickness between constructive interference of a monochromatic light and destructive interference of the said monochromatic light. The difference in the intensity of a reflected light beam subjected to interferometric constructive and destructive interference is used to communicate digital data from the optically-reflective layers and a detector. The optical disk provides for multiple layers of digital information that are tuned for interferometric response at correspondingly different monochromatic wavelengths of light. Another embodiment of the present invention is a mass-production process for making such an interferometric optical disk. Another embodiment of the present invention is a variation that includes layers that are emitting or absorbing depending on dopants.

## Claims

### Claim 1

An optical storage media, comprising:
a first plastic film layer having a first thickness "d1" and a second thickness "d2" that are substantially different fractions of the wavelength of a laser light;
wherein said thickness "d1" represents the storage of a digital one value and said thickness "d2" represents a digital zero value; and
wherein, an interferometric effect of light is used to respectively induce different constructive and destructive amplitude sums of laser light wavefronts in said media in said first thickness "d1" and said second thickness "d2" to extract recorded information.

### Claim 2 (depends on 1)

The media of claim 1, further comprising:
a second plastic film layer overlying and having a different complementary refractive index compared to the first plastic film layer, and including a third thickness "d3" and a fourth thickness "d4" that are substantially different fractions of the wavelength of light from one another and that provide for the reflection of laser light at corresponding different interferometric sum intensities, wherein said thickness "d3" represents the storage of a digital one value and said thickness "d4" represents a digital zero value, and wherein a pattern of thicknesses "d3" and "d4" are shadowed and duplicated by a pattern of thicknesses "d1" and "d2" to reinforce said reflection of laser light at corresponding different intensities.

### Claim 3 (depends on 1)

The media of claim 1, wherein:
a first plastic film layer further comprises a fluorescent dye dopant or an absorber providing for induced fluorescent lights or absorption that depend in their intensities on said difference between thicknesses "d1" and "d2".

### Claim 4 (depends on 3)

The media of claim 3, wherein:
thicknesses "d1" and "d2" provide for constructive and destructive interference in said reflection of laser light at corresponding different intensities and at a single laser light frequency dependent on the color of said fluorescent dye dopant or absorber.

### Claim 5 (depends on 1)

The media of claim 1, further comprising:
a reflective metal coating adjacent to the first plastic film layer and providing for the direction of light modulated by said thicknesses "d1" and "d2" back toward a source of said laser light and an associated detector.

### Claim 6 (depends on 1)

The media of claim 1, further comprising:
at least one additional plastic film layer overlying and separated from the first plastic film layer outside a depth of focus of a first source of said laser light, and each additional layer including a third thickness "d3" and a fourth thickness "d4" that are substantially different fractions of the wavelength of light from one another and that provide for the reflection of laser light from additional sources of laser light with different depths of focus at corresponding different interferometric sum intensities, wherein said thickness "d3" represents the storage of a digital one value and said thickness "d4" represents a digital zero value.

### Claim 7 (depends on 1)

The media of claim 1, further comprising:
at least one additional plastic film layer overlying and separated from the first plastic film layer independent of a depth of focus of a first source of said laser light having a first frequency corresponding to the constructive and destructive interference affects of said thicknesses "d1" and "d2", and each additional layer including a third thickness "d3" and a fourth thickness "d4" that are substantially different from one another in providing for the reflection of additional laser lights from additional sources of laser light having frequencies corresponding to the constructive and destructive interference affects of said thicknesses "d3" and "d4", wherein said thickness "d3" represents the storage of a digital one value and said thickness "d4" represents a digital zero value, and wherein corresponding digital values for each of the plastic film layers is accessible by selecting a particular frequency for a source of laser light associated with a detector.

### Claim 8

An optical disk, comprising:
a first transparent layer having a pattern of variations in thickness between a first thickness "d1" and a second thickness "d2" that differ from one another sufficiently as fractions of a light wavelength to cause a substantial interferometric difference in a first reflected beam of incident laser light between said first thickness "d1" and said second thickness "d2"; and
a first reflective layer deposited on the pattern side of the first transparent layer providing for returning said first reflected beam of incident light toward a laser light source for detection of a first information patterned in a plan distribution of said first and second thickness "d1" and "d2".

### Claim 9 (depends on 8)

The disk of claim 8, wherein:
the first reflective layer is partially reflective and partially transmits laser light deeper into said optical disk and a reflection back.

### Claim 10 (depends on 9)

The disk of claim 9, further comprising:
a second transparent layer having a pattern of variations in thickness between a third thickness "d3" and a fourth thickness "d4" that differ from one another sufficiently as fractions of a light wavelength to cause a substantial interferometric difference in a second reflected beam of incident laser light; and
a second reflective layer deposited on the pattern side of the second transparent layer and providing for returning said second reflected beam of incident light toward a second laser light source for detection of a second information patterned in a plan distribution of said third and fourth thickness, "d3" and "d4";
wherein, the second transparent layer and the second reflective layer are joined to the first transparent layer and the first reflective layer and said second reflected beam of incident laser light must pass through the first transparent layer and the first reflective layer.

### Claim 11 (depends on 10)

The disk of claim 10, wherein:
said first and second reflected beams of incident light are and have substantially different light wavelengths.

### Claim 12

A data storage medium, comprising:
interferometer means for storing digital information in a plastic film and reflective film combination by patterning a variation of said plastic film thickness between two thickness, each thickness corresponding to substantially different fractions of a single monochromatic light wavelength.

### Claim 13 (depends on 12)

The medium of claim 12, wherein:
the interferometer means further stores additional digital information in additional plastic film and reflective film combinations laminated to said first combination within a patterning of a variation of said additional plastic film thickness between pairs of more thickness that are independent of said first combination, with additional pair of thickness each corresponding to substantially different fractions of additional monochromatic light wavelengths independent of said single monochromatic light wavelength.