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US6023451A Optical recording medium and optical disk apparatus 失效
光记录介质和光盘装置

Optical recording medium and optical disk apparatus
摘要:
An optical recording medium according to the present invention includes a base layer having an information signal portion formed on a surface on the side on which laser light is incident, and a light transmissive layer formed on the base layer. A thickness t of the light transmissive layer is within the range of t=3 to 177 .mu.m at least in an area of the information signal portion. If unevenness of the light transmissive layer is .DELTA.t, N.A. of an optical system for reproduction or recording and reproduction and a wavelength .lambda. satisfies .DELTA.t.ltoreq..+-.5.26 (.lambda./N.A..sup.4) (.mu.m). A track pitch is P and a skew is .THETA., then P.ltoreq.0.64 .mu.m and .THETA..ltoreq..+-.84.115.degree. (.lambda./N.A..sup.3 /t) are satisfied. The optical recording medium is recorded or reproduced by a recording and reproducing system satisfying .lambda..ltoreq.0.68 .mu.m and N.A./.lambda..gtoreq.1.20. The optical recording medium permits a recording capacity of 8 GB.
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