信息光学成像研究回顾、现状与展望(特邀)

从信息论的视角理解、研究、优化光学成像系统是成像科学自信息论诞生以来的一个重要研究方向,也一直在取得一系列相应的进展。但是,由于传统光学成像系统物面至像面的"固定点到点"所见即所得的图像信息采集模式,使得基于信息论的传统光学成像研究更多的具有理论上的意义,对实际应用系统的优化设计更多的是起到锦上添花的作用,难以在成像功能上有实质性的突破。随着现代光场调控技术和基于光场高阶关联的新概念光学成像技术的突破性进展,目前已经能够在成像过程中利用可控的光场时空涨落对目标图像进行编码,这对从信息论的角度理解和优化光学成像系统提出了迫切的需求,同时也为信息光学成像这一研究方向提供了全新的发展机遇。文中将回顾自信息论提出的半个多世纪以来信息光学成像的国内外发展历史,并结合目前光学成像的最新进展讨论其若干研究现状和可能的发展趋势。

A FAST CONVERGING SPARSE RECONSTRUCTION ALGORITHM IN GHOST IMAGING

A fast converging sparse reconstruction algorithm in ghost imaging is presented. It utilizes total variation regularization and its formulation is based on the Karush-Kuhn-Tucker (KKT) theorem in the theory of convex optimization. Tests using experimental data show that, compared with the algorithm of Gradient Projection for Sparse Reconstruction (GPSR), the proposed algorithm yields better results with less computation work.

Time-Evolution of X-Ray Emission Nonuniformity in Line-Shaped Laser Plasmas

The spatially and time resolved 2D images of x-ray emission of line-shaped Ti laser plasmas have been obtained with a pinhole transmission grating spectrometer coupled with a x-ray streak camera.The x-ray emission nonuniformity of the plasma is quantitatively analyzed using a perturbation spectrum analysis method.The results show that the nonuniformity has a minimum value at a time corresponding to the peak time of the pumping laser pulse,and increases after that.A brief discussion on the nonuniformity mechanism has also been presented.

Experimental Study on the Properties of Line-Shaped Laser-Plasma

Line-focused high power laser was used to irradiate a magnesium slab target in order to generate line-shaped laser-plasma.Plasma parameter profile distribution(electron temperature and electron density)on the direction perpendicular to the target surface was obtained by spectroscopic diagnostic method,which is quite different from that of the spot-shaped laser-plasmas.New experimental phenomena that can be interpreted as“plasma satellites”were also observed.

Experimental Observations of Surface Electrostatic Wave on KT-5B Tokamak

Shear Alfven waves have been successfully excited in KT-5B small tokamak by means of the one turn longitudinal loop antenna located in the shadow area.The measured antenna loadings show their rich structure,and the loadings are also found to be sensitive to the plasma current.Preliminary evidence of surface electrostatic wave was observed.

基于光学技术的新一代全球导航定位定时系统架构

全球导航卫星系统(GNSS)已经深入现代信息化智能化社会的方方面面,发挥了巨大作用。充分发挥光频参考、自由空间激光链路等光学技术优势有助于解决其进一步发展所面临的地面依赖、精度提升等问题。美国、德国、中国分别提出了基于光链路的时空参考(O-STR)、第三代全球导航定位系统(Kepler)、基于光学技术的新一代全球导航定位定时系统(O-GNSS)等概念。对基于光学技术的新一代全球导航定位定时系统的总体设计、关键技术等进行分析,综述了主要的研究进展,为推动我国时空基准和导航定位定时方面的技术发展提供参考。