CAREER: Enabling Non-Line-of-Sight Imaging with Terahertz Holography

摘要：这项工作的重点是利用太赫兹（THz）波实现能够看到隐藏物体的相机。太赫兹波是极高频率的信号（100ghz 10thz），具有独特的成像能力。除非看到抛光良好的表面，否则人眼和普通相机只能识别视线内的物体，因此位于角落附近的物体是不可见的。另一方面，太赫兹（THz）波在普通建筑表面表现出强烈的反射。使用太赫兹相机，墙壁或门可以像镜子一样出现，从而可以窥视房间和洞穴内部，否则就无法直接看到。这种能力将增强在无法到达和未知环境中的第一响应者和救援人员的视野和态势感知能力。有趣的是，下一代超高速无线通信系统可以利用非视距成像功能。未来的通信系统将配备可以作为摄像头和传输数据的天线。太赫兹通信和成像的协同作用将实现不间断的链路和用户移动性。此外，非视线成像将为虚拟/增强现实或辅助医疗保健应用程序提供厘米级精度的用户定位。拟议中的项目还将强调教育更广泛的高中生、本科生和研究生。通过使用增强现实耳机，学生将实现在现实世界中实现太赫兹成像能力可视化的软件。此外，PI将与当地的急救人员和退伍军人合作，通过研讨会对他们进行新成像技术的能力和机会的教育。本研究的目标是设计图像重建算法和硬件拓扑，以实现从单个观测点对视距（LoS）和非视距（NLoS）物体的实时3D太赫兹成像。五年职业发展计划有以下目标：1)分析在多路径成像中扭曲图像的机制，并实现算法来反转过程，以实现准确的图像重建。2)设计NLoS太赫兹成像拓扑，了解通信与成像共存的要求。3)实现同时定位和映射的方法，以及成像和通信协议之间的协同，以实现有效的信道估计。这项工作的智力优势在于了解太赫兹波在多径和多反射情况下的波前畸变，并利用这些知识实现逆散射方法，从后向散射信号重建图像。这些知识还将帮助我们了解硬件成像要求以及NLoS成像如何与通信硬件协作以实现新应用。利用周围的三维图像，提出的研究将为下一代超高速无线通信的信道估计提供一种新的方法。从长远来看，该研究将通过在敌对和未知环境中实现第一反应、监视和侦察，允许在拥挤空间中自主导航，并为成像和通信的集成提供更快的无线数据传输路径，从而为国家安全做出贡献。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Title: Non-line-of-Sight Imaging Using Terahertz WavesAbstract:This work is focused on using terahertz (THz) waves to implement cameras that see hidden objects. THz waves are extremely high frequency signals (100 GHz 10 THz) that enable unique imaging capabilities. Unless looking into a well-polished surface, human eyes and regular cameras can only discern objects that are in the line of sight, therefore an object located around a corner is not visible. On the other hand, terahertz (THz) waves exhibit strong reflections from common building surfaces. Using THz cameras walls or doors can appear as mirrors, thus allowing to peek inside rooms and cavities otherwise hidden from direct sight. Such capability will augment vision and situational awareness of first responders and rescuers in unreachable and uncharted environments. Interestingly, non-line-sight imaging capabilities could be leveraged from the next generation of ultra-fast wireless communication systems. Future communication systems will be equipped with antennas that can operate as cameras and transfer data. The synergy of THz communications and imaging will enable uninterrupted links and user mobility. Additionally, non-line-of-sight imaging will enable localization of users with centimeter-level accuracy for applications in virtual/augmented reality or assisted healthcare. The proposed project will also emphasize on educating a broader audience of high school, undergraduate, and graduate students. With the use of augmented reality headsets, the students will implement software that allows the visualization of THz imaging capabilities in the real-world. Additionally, the PI will collaborate with local first responders and military veterans to educate them through workshops on the capabilities and opportunities of the new imaging technology.The goal of this research is to design image reconstruction algorithms and hardware topologies that will enable real-time, 3D THz imaging of both line-of-sight (LoS) and non-line-of-sight (NLoS) objects from a single observation point. The five-year career-development plan has the following objectives: 1) Analyze the mechanisms that distort images in multipath imaging and implement algorithms to invert the process for accurate image reconstruction. 2) Design topologies for NLoS THz imaging and understand the requirements for communication and imaging coexistence. 3) Implement methods for simultaneous localization and mapping and synergy between imaging and communication protocols for efficient channel estimation. The intellectual merit of this work is to understand wavefront distortions of THz waves in multipath and multi-reflection scenarios and use this knowledge to implement inverse scattering methods to reconstruct images from backscattered signals. This knowledge will also help us understand the hardware imaging requirements and how NLoS imaging can collaborate with communication hardware for novel applications. Using the 3D images of the surrounding, the proposed research will provide a new approach for channel estimation for the next generation of ultrafast wireless communications. In the long term, this research will contribute to the national security by enabling first response, surveillance and reconnaissance in hostile and uncharted environment, allow autonomous navigation in crowed spaces, and provide a path for the integration of imaging and communications for faster wireless data transmission.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.