Signal Processing Using Laser Speckle Technique

Abstract

Laser speckles has been widely used as a carrier of information. Speckle pattern resulting from the interference of random scattered coherent light from an optically rough object, has been used by many authors as a medium that can code different information. Image multiplexing using a laser speckle photography technique is capable of taking two or more exposures on the same holographic plate, with translation of the plate between exposures. In this paper an extraction of three multiplexed signals using random diffuser as a carrier is presented. Interference fringes obtained displaying each signal. The detection of the difference between two images has been applied using the same technique, in the recording step for two-signal multiplexing, the double exposure speckle photography technique has been appliec for each signal a certain displacement between exposures. Two sets of interference fringes can be obtained, each displays the information of each signal. While in the filtering step the minimum fringes were allowed to pass and the difference between the two signals can be detected instead of using the maximum fringe pattern.