Record Detail

Holographic data storage system (HDSS) has
been a good candidate for a volumetric recording
technology, due to their large storage capacities and high
transfer rates, and have been researched for tens of years
after the principle of holography was first proposed.
However, these systems, called conventional 2-axis
holography, still have essential issues for commercializa-
tion of products. Collinear HDSS, in which the information
and reference beams are modulated co-axially by the same
spatial light modulator (SLM), as a new read/write method
for HDSS are very promising. With this unique config-
uration, the optical pickup can be designed as small as
DVDs, and can be placed on one side of the recording
media (disc). In the disc structure, the preformatted
reflective layer is used for the focus/tracking servo and
reading address information, and a dichroic mirror layer is
used for detecting holographic recording information
without interfering with the preformatted information. A
2-dimensional digital page data format is used and the
shift-multiplexing method is employed to increase record-
ing density. As servo technologies are being introduced to
control the objective lens to be maintained precisely to the
disc in the recording and reconstructing process, a
vibration isolator is no longer necessary. Collinear
holography can produce a small, practical HDSS more
easily than conventional 2-axis holography. In this paper,
we introduced the principle of the collinear holography and
its media structure of disc. Some results of experimental
and theoretical studies suggest that it is a very effective
method. We also discussed some methods to increase the
recording density and data transfer rates of collinear
holography.