Optical pickup and hologram device

Abstract

An optical pickup includes a hologram unit. The hologram unit includes a hologram pattern formed circular by dividing into two and then joining together first and second patterns formed in the entire circular region. The first pattern is designed to minimize a sub-beam spot on a light-receiving device based on an optical path length and wavelength when a +1-order sub-beam is taken as a light source. The second pattern is designed to minimize the sub-beam spot on the light-receiving device based on an optical path length and wavelength when a −1-order sub-beam is taken as a light source.

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