Method for producing width-modulated surface relief patterns
AssigneeRCA Corporation
InventorsMichael Thomas Gale, Arthur Herbert Firester
Life of this patent
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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.
Claims12
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.
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.
Dependencies are inferred from the claim text.