M. Hatori et al., OPERATION OF OPTICAL INFORMATION-RETRIEVAL SYSTEM USING SPATIAL LIGHT-MODULATOR, Electronics & communications in Japan. Part 2, Electronics, 79(8), 1996, pp. 12-22
Optical information retrieval systems based on Fourier optics and usin
g holographic memories of high-density recording capability, which rai
se the possibility of parallel information processing, have been propo
sed for a long time. However, the development of spatial light modulat
ors which are the key devices in such systems has been delayed conside
rably and, so far, there is no report on optical information retrieval
systems using spatial light modulators. With this as background, a sp
atial light modulator (SLM) based on a large-permittivity crystal is f
abricated and its operation in a small-size system is verified. First,
based on the function of the spatial modulator, the hologram and the
detection sections are designed and specifications of the system are d
ecided. Next, the two different schemes of synchronous and direct dete
ction methods are applied to the information retrieval of 18 bits cons
isting of nine pieces of holograms. As a result, it is understood that
retrieval is possible using even the currently available spatial ligh
t modulators. The relation between the functions of the SLM and the sy
stem also is clarified. However, there are several problems in realiza
tion of such systems, a discussion of which is presented in this paper
.