Study On Recording Conditions Of Photoresist Fourier Holograms And The Applications Of The Holograms In Anti-counterfeit

The influences of recording conditions on the SNR of the black-white digital images retrieved from Fourier transform holograms were experimentally studied. The holograms were recorded on photoresist plates using an electrical addressed TFT-LCSLM as a data input device, and a normal CCD camera was applied for detecting reconstructed images. The experiment results show that there are optimal defocus distance and exposure for the given system and recording material, and to obtain the best SNR different reference-to-object beam ratios are also needed for black-white digital images of different space frequencies. The discussions on the experimental results are given.Furthermore, three Fourier storage schemes were proposed for practical anti-counterfeiting: (1) store black-white digital images with hidden information made by image coding method, (2) store several images on the same spot with reference beams of different directions (peristeophic multiplexing), (3) store a serious of given images recorded closely (space multiplexing). Three different Fourier holograms were recorded on photoresist plates following the above three schemes using the optimized recording conditions obtained in the first part of this study work. The reconstructed images form the holograms showed some special anti-counterfeit effects.