Patent ID: 7372602
Filing Date: 2008-05-13
Classification: G11B

Abstract:
1. A holographic recording and reproducing method a) for recording data in a holographic recording medium comprising at least a recording layer in which data are to be recorded as phase information of light by projecting a signal beam and a reference beam emitted from a first light source and having a wavelength λ0 thereonto and a servo layer disposed on an opposite side of the recording layer as viewed in a direction of signal beam incidence on the holographic recording medium, the holographic recording medium having regions in which servo projection structures are formed and b) for reproducing holographic data from the holographic recording medium by projecting the reference beam onto the holographic recording medium, the holographic recording and reproducing method comprising: setting a first optical path of the signal beam so that the signal beam is projected onto other regions of the servo layer than regions in which the servo projection structures are formed; and setting a second optical path, different than the first optical path, of a servo beam emitted from a second light source and having a wavelength λ1 different from that of the signal beam so that the servo beam is projected onto one of the regions of the servo layer in which the servo projection structures are formed after passing through an objective lens through which the signal beam passes and projecting the servo beam onto the servo layer along the thus set optical path of the servo beam, the servo beam being emitted from the second light source at a same time as the signal beam and the reference beam are emitted from the first light source.