Holograms erasure

The experimental dependence of the self-diffraction intensity of the extraordinary polarized radiation on the normalized temperature r = (T— 7V)/r is shown in Fig. 1. The same figure shows the temperature dependence of the characteristic hologram-erasure time tff, which is equal to the writing time as well as to half the characteristic relaxation time of the nonlinearity. The value of, which is proportional to (J ), increases as the phase-transition point is approached, even though in this case the hologram-erasure time, which determines the stationary value of (Ref. 2), decreases. The dependence of the refraction intensity of the ordinary polarized radiation is similar in form. 

The information is read out by a second laser beam deflected onto the hologram of the manganese-bismuth film but not onto the liquid crystals. Erasure is similar to writing except that neither of the beams is modulated or coded by the liquid crystals. The point on which the two laser beams meet is therefore magnetically neutralized. The film suffers no damage, and the write, read and erase processes can be repeated at will. 

Figure 8.1 Images recorded from a distance at different times demonstrating the persis-of 75 cm from the display at different angles, tence of the hologram, (c) Erasure of the (a) 3D hologram of a sports car and the hoi- image using uniform exposure. Reprinted by ogram of a human brain recorded onto the permission from Macmillan Publishers Ltd same area after erasing the first, (b) Pictures Nature, Ref. [5], Copyright 2008.

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