Compressive Imaging Beyond One Trillion Frames Per Second

这项研究计划将开发一种视频成像系统，该系统以超过1万亿帧/秒的帧速率运行，并能够记录孤立(非重复)事件。目前没有一种相机技术可以在如此高的帧速率和视频持续时间下工作来观察孤立的事件。这种技术的主要挑战是实现极高帧速率的快速曝光所必需的短时间门控和高光照度，以及与这种高速图像采集相关的大量信息带宽。这种高速单次成像系统是一项使工程、物理和生命科学的众多应用得以实现的技术。特别是，我们计划利用通过该计划开发的超高速单镜头成像器来更好地了解极端条件下材料的动力学。这项研究可以通过更好地了解撞击对材料的影响，从健康和安全的角度对社会产生积极影响，从而促进能够更好地控制和防止对人体伤害的材料的开发。此外，通过这项研究计划，我们计划提供本科生的研究经验，为教育目的提供项目数据和实验系统，如课堂设计项目和动手实验室演示，并进一步参与针对工程学科中代表严重不足的群体的年轻学生的外联活动。这项研究计划的主要目标是开发和实验验证一种采用压缩传感(CS)的光子成像系统，用于以远高于太赫兹(THz)的帧速率进行视频采集。我们的方法利用CS提供的降维功能，从摄像机捕获的单个高分辨率二维图像中重建三维时空视频信息。因此，CS的测量效率也将缓解在极短的时间内获取大量图像数据的传统挑战。此外，我们的方法建立在时间傅立叶处理器的基础上，该处理器使用时间透镜将时间场景动态嵌入到超快激光脉冲的频谱上，从而允许使用高光谱CS相机体系结构来捕获三维时空视频信息。这种时间镜头方法充分利用了可用的光学带宽，最大限度地提高了帧速率和在一次曝光中捕获的帧的数量。我们的目标是达到超过1太赫兹的帧速率，并记录超过100帧的长度。目前还没有一种技术可以实现这种性能的结合，但这样的技术可能会对理解超快物理现象产生革命性的影响。具体地说，这种单次成像对于观察诸如破坏性的、罕见的和/或代价高昂的孤立事件是必要的，并且在超快时间尺度上极具挑战性。通过这项研究计划，我们将开发这种成像仪，研究提高图像对比度的方法，并开始探索其在理解极端条件下材料破坏方面的应用。

This research program will develop a video imaging system operating at frame rates beyond one trillion frames per second and that is capable of recording isolated (non-repetitive) events. No current camera technology can operate at these extremely high frame rates and video durations for the observation of isolated events. The primary challenges for such a technology are the short time-gating and high light irradiance necessary to achieve fast exposure times with extremely high frame rate and the massive information bandwidth associated with such high-speed image acquisition. Such a high-speed single-shot imaging system is an enabling technology for numerous applications throughout engineering and the physical and life sciences. In particular, we plan to leverage the ultrafast single-shot imager developed through this program to better understand the dynamics of materials under extreme conditions. This research can positively impact society from a health and safety perspective through better understanding of the effect of impacts on materials and thus facilitate the development of materials that can better control and prevent injuries to the human body. In addition, through this research program we plan to offer undergraduate research experiences, provide the project data and experimental system for educational purposes such as class design projects and hands-on lab demonstrations, and further our participation in outreach activities for young students from severely underrepresented groups within the engineering discipline. The primary goal of this research program is to develop and experimentally validate a photonic imaging system employing compressed sensing (CS) for video acquisition at frame rates well beyond a terahertz (THz). Our approach leverages the dimensionality reduction afforded by CS to reconstruct three-dimensional spatio-temporal video information from a single high resolution two-dimensional image captured by a camera. Thereby, the measurement efficiency of CS will also mitigate the traditional challenge of the acquisition of a large amount of image data in an extremely short amount of time. Furthermore, our approach is built upon a temporal Fourier processor using a time-lens to imprint the temporal scene dynamics onto an ultrafast laser pulse's spectrum allowing for capture of three-dimensional spatio-temporal video information using a hyperspectral CS camera architecture. This time-lens approach fully leverages the available optical bandwidth maximizing both the frame rate and the number of frames captured in a single exposure. We aim to reach frame rates beyond 1 THz and record lengths of more than 100 frames. No current technology can achieve this combination of performance, yet such a technology can be revolutionary for understanding of ultrafast physical phenomena. Specifically, such single-shot imaging is necessary for observing isolated events such as destructive, rare, and/or costly events and is extremely challenging on ultrafast time-scales. Through this research program we will develop this imager, investigate methods for increasing image contrast, and begin to explore its application to the understanding of material failure under extreme conditions.