关键词: 光参量放大/
光学相位共轭/
图像增强/
生物成像
English Abstract
Image restoration and enhancement based on phase conjugation of optical parametric amplification
Wang Cong1,2,Yang Jing1,
Pan Xiu-Juan1,
Cai Gao-Hang1,
Zhao Wei1,
Zhang Jing-Yuan3,
Cui Da-Fu1,
Peng Qin-Jun1,
Xu Zu-Yan1
1.Key Laboratory of Solid State Laser, Key Laboratory of Functional Crystal and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China;
2.University of Chinese Academy of Sciences, Beijing 100190, China;
3.Department of Physics, Georgia Southern University, Statesboro, GA 30460, USA
Fund Project:Project supported by the Science Foundation of the Chinese Academy of Science (Grant Nos. CXJJ-16M112, CXJJ-15S089) and the Natural Science Foundation of Beijing, China (Grant No. 8154055).Received Date:05 November 2016
Accepted Date:03 March 2017
Published Online:05 May 2017
Abstract:It is well known that the weak optical image can be amplified based on the optical parametric amplification (OPA), and the distorted wave-front can be recovered by the optical phase conjugation (OPC) method. In this paper, weak infrared images, which are barely recognizable after the propagation through the milk emulsion, are restored and optically amplified based on phase conjugation of OPA.The OPC property of OPA is demonstrated with a type-II phase matched nonlinear optical crystal KTiOPO4 (KTP). The near-infrared image at 1064 nm is the input of OPA as the signal beam, and a 10 Hz, mJ-level, 21 ps 532 nm laser is used as the pump beam. When the spatial and temporal overlap are achieved, the attenuated optical image is amplified. Due to the difference in polarization, the idler beam of the OPA is selected and detected with the CCD and the blurred image is restored by the re-entry of the turbid media.The resolution of restored image is 12 lines/mm, which has achieved a theoretical limit. Moreover, by combining the optical gain of the OPA process, over 17 dB image amplification is obtained, which is the highest for the OPC-based image restoration in turbid media to our knowledge. The significant improvement in image quality is also demonstrated by 160% increase of the peak signal-to-noise ratio. By taking advantage of tunability of the OPA, the operational wavelength of this technique can be extended to an optical therapeutic window, which is suitable for noninvasive image restoration, enhancement and detection.
Keywords: optical parametric amplification/
optical phase conjugation/
image enhancement/
biological imaging
