Antonelli, Terry, Stout & Kraus
Method of making optical disk master and an optical disk
 An optical disk master having a diffraction structure including guide grooves and small pre-pits of a width narrower than a diffraction limit determined by a wavelength of light used is produced by preparing a photoresist layer subjected to anti-dissolution surface treatment, narrowing the spot diameter of a zero-th diffracted beam irradiated on the photoresist layer by a super resolution optics device, and effecting high contrast development to leave behind, as it is, a portion of the photoresist layer exposed to adverse higher order diffracted beams caused by super resolution. An optical disk produced from the master has a diffraction structure including tracks and/or pre-pits formed along a spiral track or concentric tracks and having a width narrower than a diffraction limit determined by a wavelength of light used in the course of formation of the diffraction structure. 
Hitachi, Ltd. Hitachi Maxell, Ltd.
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Masaru Masumi
Ito Fujita