Phase shift grating for phase shift differential push-pull tracking
OwnerFrank Strauchinventor
Life of this patent
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Abstract
The present invention relates to a phase shift grating for phase shift differential push-pull tracking, and to an apparatus for reading from and/or writing to optical recording media using such a phase shift grating. According to the invention, the phase shift grating has two phase gratings, with grating sections on opposite sides of a line separating the two phase gratings being phase shifted by π, which have curved grating lines which are designed such that the first diffraction order of a divergent light beam diffracted by the phase shift grating essentially is a TEM01 mode. The phase shift grating is suitable for a divergent light beam.
Claims7
Phase shift grating having two phase gratings, with grating sections on opposite sides of a line separating the two phase gratings being phase shifted by π, wherein the two phase gratings have curved grating lines which are designed such that the first diffraction order of a divergent light beam diffracted by the phase shift grating essentially is a TEM01 mode.
Dependencies are inferred from the claim text.