Dependence of tracking error characteristics on objective lens shift for in-line-type differential push-pull methods using segmented gratings |
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Authors: | Masahisa Shinoda Kenya Nakai Nobuo Takeshita |
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Institution: | 1. Advanced Technology R&D Center, Mitsubishi Electric Corporation, 1 Zusho-Baba, Nagaokakyo, Kyoto, 617-8550, Japan
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Abstract: | In this paper, we present the validity of in-line-type differential push-pull methods using segmented gratings with respect
to the radial shift of an objective lens by numerical calculation for the first time. In these differential push-pull methods,
the segmented gratings for generating sub spots are divided into two to four regions each with a specific phase value and
a width. Tracking error signals are calculated with respect to the objective lens shift under parameter conditions of the
widths of the segmented regions. The obtained results show that the grating of the simpler configuration with two regions
reveals good compatibility between DVD-R and DVD-RAM compared with those with three or four regions |
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Keywords: | |
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