Open AccessHidden image recovery using a biased photorefractive crystal in the Fourier plane of an optical imaging system
Author(s) -
Haitao Gan,
Nan Xu,
Jianwei Li,
Tao Xu,
Yanping Wang,
Zhixu Sun,
Chong Ma,
Jinjin Wang,
Song Feng,
Ming Sun,
Li Li,
Chuanxiang Sheng
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.002070
Subject(s) - optics , fourier transform , diffraction , image plane , noise (video) , physics , optical correlator , signal (programming language) , materials science , fourier optics , lens (geology) , spatial light modulator , computer science , image (mathematics) , quantum mechanics , artificial intelligence , programming language
Self-diffraction can be induced using a biased photorefractive crystal in the Fourier plane of an imaging system where the light beam intensity is naturally high due to the concentration effect of an optical lens. The spatial frequency spectrum of the output image is proportional to the optical power density distribution in the Fourier plane. A photorefractive crystal with small size can be used and hence an reduced amount of biased voltage is needed to obtain significant diffraction effect in the image plane. When the input image is an overlay of a signal and a noise pattern, theoretic model reveals that the induced diffraction in the Fourier plane may be preferably applied on the noise pattern. In order to illustrate the effect experimentally, a signal from a weakly illuminated object is coupled with an overwhelming noise pattern and then the hidden signal is successfully recovered using a SBN61 crystal with an applied voltage of 800 V in the Fourier plane. Such technology can be employed in encrypted spatial communication systems for security purposes.