An optical storage medium of the present invention enables storage of data
with high precision at high speed, and rewriting of data at high speed
without an erasing process. Optical storage, reading and retrieving
methods and optical storage, reading, and retrieving apparatuses using the
medium are also provided. The optical storage medium has at least a
polarization-sensitive member having the photo-induced birefringence
property, such as a member made of polyester polymer having
cyanoazobenzene as a side chain. The above apparatuses have spatial light
modulator capable of modulating polarization. The modulator provides
information of bit of two-dimensional data to each corresponding pixel by
application or non-application of a voltage, and modulates the
polarization of the beam incident on each pixel. Thereby, a signal beam
transmitted through the spatial light modulator having a spatial
polarization modulation corresponding to the two-dimensional data is
obtained. The signal beam illuminates the optical storage medium, and at
the same time, a reference beam illuminates the same region in the medium
where the signal beam illuminates. Thus a hologram of the polarization
modulation of the signal beam corresponding to the two-dimensional data is
stored in the optical storage medium.
