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Proceedings Paper

Image blurring and deblurring using two biased photorefractive crystals in the frequency domain
Author(s): Haiyong Gan; Chong Ma; Zhixu Sun; Tao Xu; Jianwei Li; Nan Xu; Jinjin Wang; Feng Song; Chuanxiang Sheng; Ming Sun; Li Li
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Paper Abstract

In an imaging system based on a coherent source of moderate power density, images can be blurred when a biased photorefractive crystal is applied at the focal point of the imaging lens. In the frequency domain of the original images, the intensity patterns are diffracted through the photorefractive crystal with varied bias voltage. The high intensity region, which is usually the center or low frequency region of the intensity patterns, is more readily focused or defocused, resulting in blurred images in perception. Such blurred images could not be simply recovered by defocusing methods, which can only indistinguishably focus or defocus the whole intensity patterns. However, the blurred images may be deblurred to certain extent for recovery if a second photorefractive crystal with bias voltage is employed at the focal point of a tandem imaging system. The mechanism of deblurring is similar to that of blurring: the blurred images are transferred through the frequency domain again using an imaging lens, where the second biased photorefractive crystal diffracts the intensity patterns to revert the sensitive region where previously gets focused or defocused. In this work, theoretical analyses are presented in detail to explain the blurring-deblurring mechanism using two biased photorefractive crystals and compatible experimental results are obtained and illustrated. Considering the blurring and deblurring function subgroups of the experiment setup can be potentially developed into encryption and decryption units compatible with far field propagation, the technology presented herein may be promising to find applications in secure laser-based free-space communication systems.

Paper Details

Date Published: 18 November 2014
PDF: 8 pages
Proc. SPIE 9269, Quantum and Nonlinear Optics III, 926910 (18 November 2014); doi: 10.1117/12.2073476
Show Author Affiliations
Haiyong Gan, National Institute of Metrology (China)
Chong Ma, National Institute of Metrology (China)
Zhixu Sun, National Institute of Metrology (China)
Tao Xu, National Institute of Metrology (China)
Jianwei Li, National Institute of Metrology (China)
Nan Xu, National Institute of Metrology (China)
Jinjin Wang, Nankai Univ. (China)
Feng Song, Nankai Univ. (China)
Chuanxiang Sheng, Nanjing Univ. of Science and Technology (China)
Ming Sun, Nanjing Univ. of Science and Technology (China)
Li Li, Nanjing Univ. of Science and Technology (China)

Published in SPIE Proceedings Vol. 9269:
Quantum and Nonlinear Optics III
Qihuang Gong; Guang-Can Guo; Byoung Seung Ham, Editor(s)

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