Patent ID: 8149676
Filing Date: 2012-04-03
Classification: G11B

Abstract:
1. A holographic information recording and/or reproducing apparatus comprising an optical pickup emitting light onto a holographic information storage medium and receiving the emitted light, the optical pickup comprising: a light source unit configured to emit a signal beam and a reference beam in a recording mode; and a focusing optical system configured to: focus the signal beam and the reference beam on a focal point in the holographic information storage medium so that information is recorded on the holographic information storage medium using an interference pattern formed along a depth direction of the holographic information storage medium in a vicinity of the focal point, a numerical aperture of the focusing optical system for the reference beam being greater than a numerical aperture of the focusing optical system for the signal beam so as to decrease an amount of occurrence of aberration; and vary the focal point along the depth direction of the holographic information storage medium to record information in multiple layers.