Fischell Department of Bioengineering, University of Maryland, 8278 Paint Branch Drive, College Park, MD, 20742, USA.
Sci Rep. 2019 Aug 2;9(1):11256. doi: 10.1038/s41598-019-47679-3.
Focusing light through highly scattering materials by modifying the phase profile of the illuminating beam has attracted a great deal of attention in the past decade paving the way towards novel applications. Here we report on a tradeoff between two seemingly independent quantities of critical importance in the focusing process: the size of the focal point obtained behind a scattering medium and the maximum achievable intensity of such focal point. We theoretically derive and experimentally demonstrate the practical limits of intensity enhancement of the focal point and relate them to the intrinsic properties of the scattering phenomenon. We demonstrate that the intensity enhancement limitation becomes dominant when the focusing plane gets closer to the scattering layer thus limiting the ability to obtain tight focusing at high contrast, which has direct relevance for the many applications exploring scattering materials as a platform for high resolution focusing and imaging.
通过改变照明光束的相位分布来聚焦高度散射的材料在过去十年中引起了极大的关注，为新的应用铺平了道路。在这里，我们报告了在聚焦过程中两个看似独立的关键量之间的权衡：在散射介质后面获得的焦点的大小和该焦点的最大可实现强度。我们从理论上推导并实验证明了焦点强度增强的实际限制，并将其与散射现象的固有特性联系起来。我们证明，当聚焦平面更接近散射层时，强度增强限制变得占主导地位，从而限制了在高对比度下获得紧密聚焦的能力，这对于许多探索将散射材料作为高分辨率聚焦和成像平台的应用具有直接的相关性。
