Image blurring and deblurring using two biased photorefractive crystals in the frequency domain

Haiyong Gan; Chong Ma; Zhixu Sun; Tao Xu; Jianwei Li; Nan Xu; Jinjin Wang; Feng Song; Chuanxiang Sheng; Ming Sun; Li Li

doi:10.1117/12.2073476

18 November 2014 Image blurring and deblurring using two biased photorefractive crystals in the frequency domain

Haiyong Gan, Chong Ma, Zhixu Sun, Tao Xu, Jianwei Li, Nan Xu, Jinjin Wang, Feng Song, Chuanxiang Sheng, Ming Sun, Li Li

Author Affiliations +

Proceedings Volume 9269, Quantum and Nonlinear Optics III; 926910 (2014) https://doi.org/10.1117/12.2073476
Event: SPIE/COS Photonics Asia, 2014, Beijing, China

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.

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Haiyong Gan, Chong Ma, Zhixu Sun, Tao Xu, Jianwei Li, Nan Xu, Jinjin Wang, Feng Song, Chuanxiang Sheng, Ming Sun, and Li Li "Image blurring and deblurring using two biased photorefractive crystals in the frequency domain", Proc. SPIE 9269, Quantum and Nonlinear Optics III, 926910 (18 November 2014); https://doi.org/10.1117/12.2073476

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