Angle-Sensitive Metasurfaces for Lens-Free Compound-Eye Cameras

职务名称：非技术描述：该项目旨在开发一种新的相机技术，具有极端尺寸小型化的特点，灵感来自于自然界中常见的小型无脊椎动物（如昆虫和甲壳类动物）的复眼视觉模式。复眼通常由许多成像元件（包括透镜和光感受器）的弯曲阵列组成，每个成像元件被定向为检测沿沿着不同方向入射的光。然后从所有这些元素的组合输入重建被可视化的对象的完整图像。这种视觉模态的光电实现通常由于其弯曲的架构而变得复杂，因为标准的光电器件是基于平面衬底的。复眼视觉模式代表了最佳适应解决方案，可在最小的封装内提供广角视野，失真可忽略不计。此外，复眼可以在任意距离处创建物体的聚焦图像，而无需任何焦距调整，因此提供了几乎无限的景深和极高的运动敏锐度。因此，所提出的相机可以为广泛的成像应用提供使能技术，其中小尺寸、大视场和高时间分辨率是特别重要的。具体示例包括机器视觉（例如，用于避障和自主导航）、监视和内窥镜医学成像。拟议的活动还将通过在纳米光子学、光电子学和图像处理领域的广泛专题中培训研究生和本科生来促进教育。相关的课程开发工作将影响其他学科的学生。技术描述：拟议的研究将利用纳米光子学和超材料的最新进展，开发一种由成像像素平面阵列组成的平面无透镜复眼相机。每个像素的角度选择性由在每个光电探测器的表面上图案化的金属纳米颗粒（光学超颖表面）的专门设计的阵列提供。提出的研究的关键创新是超颖表面的发展，可以选择性地传输到他们的基板只有光入射沿着一个单一的几何可调方向（在一个小范围内）。沿沿着任何其他方向入射的光将被反射。通过这种布置，可以使用现有的CMOS或CCD图像传感器阵列来实现无透镜复眼相机。每个像素将被涂上一个不同的超颖表面，以允许检测来自不同方向的光。所提出的角度敏感光电探测器将通过全波数值模拟设计，在硅衬底上制造，并通过角度分辨光电流测量进行表征。然后将开发这些设备的阵列，以验证其成像能力的概念。将采用先进的计算成像算法来优化来自各个传感器的组合信号的图像重建。除了所提出的相机的潜在技术影响外，这项研究还将通过探索新颖的设计和应用来推进光学超颖表面的科学和技术，并将在新兴的计算成像领域创造新的研究机会。

Title: Metasurfaces for Lens-Free Compound-Eye Cameras Non-Technical Description:This project aims at developing a new camera technology featuring extreme size miniaturization, inspired by the compound-eye vision modality that is commonly found in nature in small invertebrates such as insects and crustaceans. Compound eyes typically consist of a curved array of many imaging elements (including lenses and photoreceptors), each oriented so as to detect light incident along a different direction. The full image of the object being visualized is then reconstructed from the combined inputs of all such elements. The optoelectronic implementation of this vision modality is generally complicated by its curved architecture, since standard optoelectronic devices are based on planar substrates. The compound-eye vision modality represents the optimally adapted solution to provide wide-angle field of view with negligible distortion within the smallest possible package. Furthermore, compound eyes can create focused images of objects at arbitrary distances without the need for any focal-length adjustment, and thus offer nearly infinite depth of field and extremely high acuity to motion. The proposed cameras could therefore provide an enabling technology for a wide range of imaging applications where small size, large field of view, and high temporal resolution are of particular importance. Specific examples include machine vision (e.g., for obstacle avoidance and autonomous navigation), surveillance, and endoscopic medical imaging. The proposed activities will also promote education through the training of graduate and undergraduate students in a wide range of topics within nanophotonics, optoelectronics, and image processing. Related curriculum development efforts will impact students in other disciplines.Technical Description:The proposed research will leverage recent advances in nanophotonics and metamaterials to develop a planar lens-free compound-eye camera consisting of a planar array of imaging pixels. The angle selectivity of each pixel is provided by specially designed arrays of metallic nanoparticles (optical metasurfaces) patterned on the surface of each photodetector. The key innovation of the proposed research is the development of metasurfaces that can selectively transmit into their substrate only light incident along a single geometrically tunable direction (within a small range). Light incident along any other direction will be reflected. With this arrangement, lens-free compound-eye cameras can be implemented using existing CMOS or CCD image-sensor arrays. Each pixel will be coated with a different metasurface designed to allow for the detection of light from a different direction. The proposed angle-sensitive photodetectors will be designed via full-wave numerical simulations, fabricated on silicon substrates, and characterized through angle-resolved photocurrent measurements. Arrays of these devices will then be developed for a proof-of-concept demonstration of their imaging capabilities. Advanced computational imaging algorithms will be employed to optimize the image reconstruction from the combined signals of the individual sensors. In addition to the potential technological impact of the proposed cameras, this research will also advance the science and technology of optical metasurfaces through the exploration of novel designs and applications, and will create new research opportunities in the emerging field of computational imaging.