Hsuan T. CHANG^* and Ching T. CHEN

Photonics and Information Laboratory, Department of Electrical Engineering, National Yunlin University of Science and Technology, 123, Sec. 3, University Road, Touliu Yunlin, 64045 Taiwan, R.O.C.

(Received August 29, 2003; Accepted February 19, 2004)

In this paper two new architectures for optical image verification are proposed. Both architectures are based on conventional joint transform correlators (JTCs) adopting a Fourier hologram and can significantly improve the recovered image quality. First, an input phase-only function is Fourier transformed and then interferes with a reference wave that is diffracted from a plane wave incident on another random phase mask. Second, two phase-only functions are placed at the two input sides of a beamsplitter such that the interference pattern of their Fourier transforms can be detected. To obtain a predefined target image in the output plane, one of the input phase functions is iteratively retrieved by the use of the projection onto constraint sets algorithm. Simulation results show that the less mean squared error and better image quality are obtained for both the binary and grayscale images.

Key words: optical security, joint transform correlator, image verification, phase retrieval, iteration algorithm

^*E-mail address: htchang@pine.yuntech.edu.tw