Patent US3945825A successfully refreshed from Google Patents.
US3945825A
Expired / Lapsed
US
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Method for producing width-modulated surface relief patterns
Assignee: RCA Corp
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Filing: 1974-05-22
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Granted: 1976-03-23
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Expires: 1994-05-22
Abstract
Abstract Pulse width modulated surface relief phase holograms are produced on a substrate by developing a holographic interference pattern recorded on a photoresist deposited on the surface of said substrate as an amplitude modulated sinusoidal surface relief pattern so as to expose the surface of said substrate as a function of the intensity of said interference pattern, uniformly etching said substrate and removing said photoresist leaving a pulse width modulated, substantially two-level rectangular wave diffraction grating. Focused image holograms produced by this method on hard durable substrates may be used as masters for replicating said holograms in a suitable recording medium.
Inventors
- 👤 Michael Thomas Gale
- 👤 Arthur Herbert Firester
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:17
CPC Classifications
G; G03; G03H; G03H1/00; G03H1/04; G03H1/0402; G03H1/0406; G03F; G03F7/00; G03F7/0005; G03F7/001; G03H1/02; G03H1/0276; G03H1/024; G03H1/0244; G03H2001/0292; G03H2001/0296; G03H2240/00; G03H2240/20; G03H2240/40; G03H2240/41; G03H2260/00; G03H2260/14; G03H2260/50; G03H2260/63; G03H2270/00; G03H2270/10; G03H2270/11; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
126 words
A method for producing a width-modulated surface relief pattern in the surface of a substrate that is covered with a coating of substantially uniform thickness of photoresist, said method comprising the steps of: a. exposing the photoresist to surface radiation including an interference pattern, b. developing the exposed photoresist just sufficiently to produce an amplitude-modulated surface relief pattern which reveals only certain portions of the surface of the substrate as a function of the spatial distribution of the relative intensity of said surface radiation, c. etching only the revealed certain portions of said substrate to form a width-modulated wave grating of substantially rectangular cross section and substantially uniform depth in the substrate, and d. only then removing the photoresist from the now-revealed remainder of the substrate.
Claim 2
Independent Claim
126 words
A method for producing a width-modulated surface relief pattern in the surface of a substrate that is covered with a coating of substantially uniform thickness of photoresist, said method comprising the steps of: a. exposing the photoresist to surface radiation including an interference pattern, b. developing the exposed photoresist just sufficiently to produce an amplitude-modulated surface relief pattern which reveals only certain portions of the surface of the substrate as a function of the spatial distribution of the relative intensity of said surface radiation, c. etching only the revealed certain portions of said substrate to form a width-modulated wave grating of substantially rectangular cross section and substantially uniform depth in the substrate, and d. only then removing the photoresist from the now-revealed remainder of the substrate.
Claim 3
Dependent Claim
16 words
The method of claim 1 wherein said surface radiation comprises a focused image holographic interference pattern.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein said etching is produced by chemical etching.
Claim 5
Dependent Claim
12 words
The method of claim 1 wherein said etching is produced by sputter-etching.
Claim 6
Dependent Claim
34 words
The method of claim 1 wherein said photoresist is exposed to a substantially constant, substantially uniform weak grating pattern biased by a more intense, incoherent object pattern prior to exposure to said interference pattern.
Claim 7
Dependent Claim
11 words
The method of claim 5 wherein said development is substantially non-linear.
Claim 8
Dependent Claim
11 words
The method of claim 1 wherein said development is substantially linear.
Claim 9
Dependent Claim
11 words
The method of claim 1 wherein said development is substantially non-linear.
Claim 10
Dependent Claim
26 words
The method of claim 1 wherein said photoresist is exposed to surface radiation comprising a focused image of an object after exposure to said interference pattern.
Claim 11
Dependent Claim
35 words
The method of claim 1 wherein said substrate is a hard durable substrate capable of being used as a master for replicating said width modulated surface relief pattern by hot pressing of a thermoplastic medium.
Claim 12
Dependent Claim
40 words
The method of claim 10 wherein said substrate is etched to an optimum depth which is a direct function of the wavelength of the exposing surface radiation and an inverse function of the index of refraction of said thermoplastic medium.
Claim 13
Independent Claim
130 words
A method for producing a width-modulated surface relief pattern comprising the steps of: a. depositing a thin amorphous film on a substrate, b. coating said film with a substantially uniform thickness of photoresist, c. exposing said photoresist to surface radiation including an interference pattern, d. developing said exposed photoresist just sufficiently to produce an amplitude-modulated surface relief pattern which reveals only certain portions of the surface of the thin film as a function of the spatial distribution of the relative intensity of said surface radiation, e. etching only the revealed certain portions of said thin film to form a width-modulated wave grating of substantially rectangular cross section and substantially uniform depth in said thin film, and f. only then removing the photoresist from the non-revealed remainder of the thin film.
Claim 14
Independent Claim
130 words
A method for producing a width-modulated surface relief pattern comprising the steps of: a. depositing a thin amorphous film on a substrate, b. coating said film with a substantially uniform thickness of photoresist, c. exposing said photoresist to surface radiation including an interference pattern, d. developing said exposed photoresist just sufficiently to produce an amplitude-modulated surface relief pattern which reveals only certain portions of the surface of the thin film as a function of the spatial distribution of the relative intensity of said surface radiation, e. etching only the revealed certain portions of said thin film to form a width-modulated wave grating of substantially rectangular cross section and substantially uniform depth in said thin film, and f. only then removing the photoresist from the non-revealed remainder of the thin film.
References Cited (Backward Citations)
US3388735A
Cited
US3580657A
Cited
US3623798A
Cited
US3669673A
Cited
US3743507A
Cited
US3733258A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-23 | 1979-09-22 | 1980-03-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-23 | 1983-09-22 | 1984-03-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-23 | 1987-09-22 | 1988-03-23 | $7700.00 | Window Closed / Lapsed |