Manufacturing method of optical diffraction grating element with serrated gratings having uniformly etched grooves
First Claim
1. A method of manufacturing an optical diffraction grating element comprising:
- (a) forming a resist film upon a transparent substrate, wherein said resist film and substrate are divided into plurality of regions;
(b) exposing and developing each of said plurality of regions in said resist film for forming a plurality of diffraction grating patterns corresponding to each of said plurality of regions having slits free of resist film; and
(c) etching said resist film and said transparent substrate by irradiation of an ion beam upon a surface of said transparent substrate at a fixed angle, to form upon said transparent substrate a plurality of diffraction gratings having serrated profiles and mutually different diffraction angles with respect to an incident light,wherein said slits formed during said exposing and developing process are designed such as to have a substantially constant width irrespectively of said plurality of diffraction grating patterns.
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Abstract
The method of manufacturing an optical diffraction grating element of the present invention is characterized in adopting an ion beam made from a gas chemically reacting with a glass substrate when forming a diffraction grating having a serrated profile upon the glass substrate through an ion beam etching method. Also, when manufacturing an optical diffraction grating element that is divided into a plurality of regions whereon diffraction gratings having different diffraction angles with respect to an incident light are provided, the method of the present invention is characterized in forming slits into a resist film disposed upon a transparent substrate such as a glass substrate, in accordance with the patterns of the diffraction gratings, such that the width of the slits is constant irrespectively of the regions. Accordingly, the method of manufacturing an optical diffraction grating element of the present invention enables to improve the diffraction efficiency of the optical diffraction grating element, and to enhance the optical efficiency of an optical head device. The SN ratio of the output signals released by the optical head device may be thus improved and the servo error control executed accurately.
42 Citations
12 Claims
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1. A method of manufacturing an optical diffraction grating element comprising:
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(a) forming a resist film upon a transparent substrate, wherein said resist film and substrate are divided into plurality of regions; (b) exposing and developing each of said plurality of regions in said resist film for forming a plurality of diffraction grating patterns corresponding to each of said plurality of regions having slits free of resist film; and (c) etching said resist film and said transparent substrate by irradiation of an ion beam upon a surface of said transparent substrate at a fixed angle, to form upon said transparent substrate a plurality of diffraction gratings having serrated profiles and mutually different diffraction angles with respect to an incident light, wherein said slits formed during said exposing and developing process are designed such as to have a substantially constant width irrespectively of said plurality of diffraction grating patterns. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification