Non-invasive, high-resolution, 3D imaging and sensing through highly scattering materials

该项目探索和开发技术，使高保真成像和光聚焦内部和通过混浊介质，如生物组织。研究的方法是非侵入性的，联合收割机结合光学和声学。最先进的高分辨率三维光学显微镜技术已经在生物和生物医学应用中产生了强大的影响。目前的商业模式包括成熟的技术，如共焦显微镜，双光子显微镜和光学相干断层扫描。不幸的是，一个共同的缺点是有限的渗透到生物组织超过1毫米的分数，这个问题的核心建议。组织中的高分辨率深度成像将使许多生物医学研究和诊断工具成为可能，例如血氧成像或改善光动力治疗。这项研究将为本科生和研究生创造机会，参加与这项建议相关的跨学科合作项目。该项目还将在生物医学光学成像方面开展广泛的教育活动。自适应波前整形的最新进展使通过散射环境成像成为可能。通过预补偿光学波前，可以控制光传播通过和超出散射材料。然而，大多数现有的技术，是有限的，他们需要从后面或内部的散射介质产生一个反馈信号，直接侵入式访问，在大多数生物医学成像方案是不可能的。该项目强调解决深度，高分辨率成像和聚焦需求的基本发展，以解决新兴应用。响应于光场产生声波的光声效应为波前优化提供了一种新的反馈机制，因为声波在组织中传播时几乎没有散射。因此，通过检测散射介质表面的声波，获得有效且非侵入性的反馈信号以指导波前补偿。此外，声换能器的空间非均匀灵敏度可以用于将光引导到基本上小于声聚焦区域的点。然而，由于来自血流和生理运动的散斑场的快速变化率以及生物组织深处的散斑尺寸在波长的量级上的事实，通过真实的生物材料和在其中的光学聚焦和成像仍然是一个挑战。在这个项目中，将探讨在散射介质中聚焦的基本和实验限制，波前补偿算法将优化聚焦速度和通量增强，并将研究在足以克服生物介质中散斑去相关的速度下实现波前补偿的硬件开发。

This project explores and develops techniques to enable high-fidelity imaging and light focusing inside and through turbid media such as biological tissue. The methods investigated are non-invasive and combine optics and acoustics. State-of-the-art high-resolution three-dimensional optical microscopy techniques have already generated a strong impact in biological and biomedical applications. Current commercial modalities include mature technologies such as confocal microscopy, two-photon microscopy, and optical coherence tomography. Unfortunately, a common shortcoming is the limited penetration into biological tissue beyond a fraction of 1 mm, the problem at the core of this proposal. High-resolution deep imaging in tissue would enable numerous biomedical research and diagnosis tools such as imaging of blood oxygenation or improving photodynamic therapy. The research will create opportunities for undergraduate and graduate students to join in collaborative interdisciplinary projects associated with this proposal. The project will also enable broad educational activities in biomedical optical imaging.Recent advances in adaptive wavefront shaping have made imaging through scattering environments a possibility. By pre-compensating the optical wavefront, light propagation can be controlled through and beyond scattering materials. Most existing techniques, however, are limited by their need to generate a feedback signal from behind or inside the scattering media with direct invasive access, something not possible in the majority of biomedical imaging scenarios. This project emphasizes fundamental developments that address the need for deep, high-resolution imaging and focusing to tackle emerging applications. The photoacoustic effect, where acoustic waves are generated in response to an optical field, offers a new feedback mechanism for wavefront optimization because acoustic waves propagate in tissue with little scattering. Hence by detecting the acoustic waves at the surface of the scattering media, an effective and noninvasive feedback signal is obtained to guide wavefront compensation. Furthermore, the spatially nonuniform sensitivity of the acoustic transducer can be used to guide the light to a point that is substantially smaller than the acoustic focal region. Nevertheless, optical focusing and imaging through and within real biological materials remains a challenge due to the fast rate of change of the speckle field from blood flow and physiological motion and the fact that the speckle size deep in biological tissue is on the order of a wavelength. In this project, fundamental and experimental limitations on focusing in scattering media will be explored, algorithms for wavefront compensation will be optimized for focusing speed and fluence enhancement, and hardware developments for implementing wavefront compensation at speeds sufficient to overcome speckle decorrelation in biological media will be investigated.