Characters for optical filter of removing bright-background based on bacteriorhodopsin film

Special property of complementary suppression modulated transmission (CSMT) of bacteriorhodopsin (bR) film was used to establish a new kind of optical filter, which can be used to remove incoherent bright-background in optical image. This new kind of optical filter was demonstrated and its behavior was analyzed theoretically. The calculated results showed that the quality (the contrast, the transmitted intensity and the space distribution) of the processed image is affected by the parameters (concentration and lifetime of M state) of bR film and the intensity of the bias light. With the increase of bR film concentration, the transmitted intensity and the curvature degree of the space distribution of the transmitted intensity decrease, and the contrast increases to the maximum and then decreases to zero. By prolonging the lifetime of M state, the transmitted intensity and its curvature degree of space distribution increase and the contrast increases to the stable value. Accompanying the increase of the intensity of the bias light, the transmitted intensity decreases, the space distribution is not changed, and the contrast can be increased to 1. But when the concentration of bR film, the lifetime of M state and the intensity of the bias light are too large, the processed image would be distorted.