Jin Curtis, Nadakuditi Raj Rao, Michielssen Eric, Rand Stephen C
J Opt Soc Am A Opt Image Sci Vis. 2013 Aug 1;30(8):1592-602. doi: 10.1364/JOSAA.30.001592.
Scattering hinders the passage of light through random media and consequently limits the usefulness of optical techniques for sensing and imaging. Thus, methods for increasing the transmission of light through such random media are of interest. Against this backdrop, recent theoretical and experimental advances have suggested the existence of a few highly transmitting eigen-wavefronts with transmission coefficients close to 1 in strongly backscattering random media. Here, we numerically analyze this phenomenon in 2D with fully spectrally accurate simulators and provide rigorous numerical evidence confirming the existence of these highly transmitting eigen-wavefronts in random media with periodic boundary conditions that are composed of hundreds of thousands of nonabsorbing scatterers. Motivated by bio-imaging applications in which it is not possible to measure the transmitted fields, we develop physically realizable algorithms for increasing the transmission through such random media using backscatter analysis. We show via numerical simulations that the algorithms converge rapidly, yielding a near-optimum wavefront in just a few iterations. We also develop an algorithm that combines the knowledge of these highly transmitting eigen-wavefronts obtained from backscatter analysis with intensity measurements at a point to produce a near-optimal focus with significantly fewer measurements than a method that does not utilize this information.
散射阻碍光通过随机介质，从而限制了光学传感和成像技术的实用性。因此，提高光通过此类随机介质的传输方法备受关注。在此背景下，最近的理论和实验进展表明，在强后向散射随机介质中存在一些传输系数接近1的高透射本征波前。在这里，我们使用全光谱精确模拟器对二维中的这一现象进行数值分析，并提供严格的数值证据，证实了在由数十万非吸收性散射体组成的具有周期性边界条件的随机介质中存在这些高透射本征波前。受生物成像应用中无法测量透射场的启发，我们开发了基于后向散射分析来提高通过此类随机介质传输的物理可实现算法。我们通过数值模拟表明，这些算法收敛迅速，只需几次迭代就能产生接近最优的波前。我们还开发了一种算法，该算法将从后向散射分析中获得的这些高透射本征波前的知识与某一点的强度测量相结合，以产生一个接近最优的焦点，与不利用此信息的方法相比，所需的测量次数显著减少。
