Compressive Imaging Beyond One Trillion Frames Per Second

该研究项目将开发一种帧率超过每秒一万亿帧的视频成像系统，能够记录孤立的（非重复的）事件。目前没有任何相机技术能够以如此高的帧率和视频持续时间来观察孤立事件。这种技术的主要挑战是短时间门控和高光辐照度，以实现极高帧速率的快速曝光时间，以及与这种高速图像采集相关的大量信息带宽。这种高速单发成像系统是工程、物理和生命科学领域众多应用的使能技术。特别是，我们计划利用通过该计划开发的超快单镜头成像仪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冲击对材料的影响，从健康和安全的角度对社会产生积极的影响，从而促进能够更好地控制和预防对人体伤害的材料的开发。此外，通过这个研究项目，我们计划为本科生提供研究经验，为教学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，并进一步参与工程学科中代表性严重不足的群体的年轻学生的推广活动。本研究计划的主要目标是开发并实验验证采用压缩传感（CS）的光子成像系统，用于帧率远远超过太赫兹（THz）的视频采集。我们的方法利用CS提供的降维功能，从相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传统在极短时间内获取大量图像数据的挑战。此外，我们的方法建立在一个时间傅里叶处理器上，使用一个时间透镜将时间场景动态印在超快激光脉冲的光谱上，允许使用高光谱CS相机架构捕获三维时空视频信息。这种时间透镜方法充分利用了可用的光带宽，最大限度地提高了帧速率和单次曝光中捕获的帧数。我们的目标是达到超过1太赫兹的帧率和超过100帧的记录长度。目前还没有技术可以实现这种性能的结合，但这种技术对于理解超快物理现象来说是革命性的。具体来说，这种单次成像对于观察孤立事件（如破坏性，罕见和/或昂贵事件）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，并开始探索其在极端条件下对材料失效的理解的应用。

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.