Abstract

The photochromic protein bacteriorhodopsin (bR), which is related to the human visual pigment, is found in the purple membrane of Halobacterium halobium in two-dimensional crystallized form. The absorption of a visible photon by bR triggers a photocycle as shown in Fig. 1. Both the forward and reverse photoreactions produce stable products in less than 3 picoseconds at 77 K. Its photochromic properties, i.e., the light-driven reversible color changes, are used in real-time holographic recording.

© 1994 IEEE