Next Generation High-Speed Microplasma Three- Dimensional Imaging

该项目的目标是首次探索用于研究电离气体（称为等离子体）的计算显微镜。在过去的世纪里，科学家们对等离子体组成的宏观和微观系统进行了深入的研究。一段时间以来，实验室规模等离子体的光学研究一直由几种众所周知的技术主导，新技术的发展停滞严重限制了使用光作为探针的测量所能获得的信息。最近，新的和变革性的显微镜，使图像与强大的计算机算法的帮助下，导致不断增加的信息量提取的物理系统，即使是相同数量的收集数据。有了这些进步，现在可以使用一个单一的，短的光脉冲来成像物体的厚度或高度，以及它们的材料组成。该项目将使新的计算显微镜技术应用于微等离子体的研究。 释放光的能量作为一种非破坏性的，非侵入性的探测器，如等离子体的恶劣环境，将对各种领域产生直接的影响，包括材料科学，粒子加速器和替代光源，所有这些都基于激光产生的plasma.Fundamental限制纹影成像，成像干涉术，阴影术和泽尼克相衬成像是众所周知的分析计算。 纹影成像对与样品的折射率的第一方向导数相关的量敏感，并且阴影术可以在某些近似下产生与折射率的第二导数成比例的图像。然而，这一信息是定性的。 干涉成像需要已知的参考，相对较小的相移，并且对振动非常敏感;它还需要在参考波和询问波之间仔细计时，因此在实验上更加复杂。阴影术是最简单的实验配置，但却是最复杂的分析方法;虽然Zernike相位衬度成像是一种出色的技术，但它无法产生具有同时相位和振幅的无参考图像。只有相干计算成像能够产生定量的、单次激发的、无参考的图像，同时具有相位和幅度对比度-在一定频率范围内，在三维中。这种能够探测等离子体的真正定量的同步相位和振幅对比成像技术的发展预计将对实验室等离子体的基础和应用研究产生变革性影响。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

The goal of this project is a first exploration of computational microscopy for the study of ionized gasses, called plasmas. Over the last century, scientists have intensely investigated macro- and microscopic systems composed of plasmas. Optical investigations of laboratory scale plasmas have been dominated by several well-known techniques for some time, and stagnation in development of new techniques has critically limited information accessible to measurements that use light as a probe. Recently, new and transformative microscopes that make images with assistance from powerful computer algorithms have led to an ever-increasing amount of information extracted from physical systems, even for the same amount of collected data. With these advances, it is now possible to image the thickness or height of objects, and their material composition all in three-dimensions using a single, short burst of light. This project will enable application of the new computational microscopy techniques to the study of microplasmas. Unlocking the power of light as a nondestructive, noninvasive probe of harsh environments like plasmas will have immediate impact on a variety of fields including material science, particle accelerators, and alternative light sources, all based on laser created plasmas.Fundamental limits of Schlieren imaging, imaging interferometry, shadowgraphy, and Zernike phase contrast imaging are well known from analytic calculations. Schlieren imaging is sensitive to a quantity that is related to the first, directional derivative of the specimen’s refractive index and shadowgraphy can produce images proportional to the second derivative of the refractive index under certain approximations. However, this information is qualitative in nature. Interferometric imaging requires a known reference, relatively small phase shifts, and is quite sensitive to vibrations; it also requires careful timing between the reference wave and the interrogating wave and is therefore more experimentally complicated. Shadowgraphy is the simplest experimental configuration but is the most complicated method to analyze; and while Zernike phase contrast imaging is an excellent technique, it is not capable of producing reference free images with simultaneous phase and amplitude. Only coherent computational imaging is capable of producing quantitative, single-shot, reference free images with simultaneous phase and amplitude contrast -- over a range of frequencies, in three-dimensions. The development of such truly quantitative simultaneous phase-and-amplitude contrast imaging technique capable of probing plasmas is expected to be transformative for both fundamental and applied studies of laboratory plasmas.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.