Asymmetric metasurface photodetectors for single-shot quantitative phase imaging
Asymmetric metasurface photodetectors for single-shot quantitative phase imaging
复制标题
DOI：
10.1515/nanoph-2023-0354
复制
发表时间：
2023-08-02
期刊：
影响因子：
7.5
通讯作者：
Paiella, Roberto
中科院分区：
文献类型：
--
作者：
Liu, Jianing;Wang, Hao;Paiella, Roberto
通过波前传感的纯相位物体的可视化具有从表面轮廓到生物医学显微镜的重要应用，并且通常需要涉及光学空间滤波、干涉测量或结构化照明的庞大且复杂的设置。在这里，我们介绍了一种新型的图像传感器，是唯一敏感的光传播的局部方向，基于标准的光电探测器涂有一个专门设计的等离子体元表面，创建一个不对称的依赖于周围的表面法线的入射角的响应度。超颖表面的设计，制造和角度敏感的操作演示使用一个简单的光电导探测器平台。测量结果与计算成像计算相结合，然后用于显示基于这些元表面像素的标准相机或显微镜可以直接可视化相位对象，而无需任何额外的光学元件，最先进的最小可检测相位对比度低于10 mrad。此外，在同一像素阵列上具有相等和相反角度响应的传感器的组合可以用于在单次激发中执行定量相位成像，其中还开发了定制的重建算法。凭借其系统小型化和测量简单性，这些器件实现的相位成像方法对于涉及空间受限和便携式设置（例如床旁成像和内窥镜检查）的应用以及涉及自由移动物体的测量特别重要。
The visualization of pure phase objects by wavefront sensing has important applications ranging from surface profiling to biomedical microscopy, and generally requires bulky and complicated setups involving optical spatial filtering, interferometry, or structured illumination. Here we introduce a new type of image sensors that are uniquely sensitive to the local direction of light propagation, based on standard photodetectors coated with a specially designed plasmonic metasurface that creates an asymmetric dependence of responsivity on angle of incidence around the surface normal. The metasurface design, fabrication, and angle-sensitive operation are demonstrated using a simple photoconductive detector platform. The measurement results, combined with computational imaging calculations, are then used to show that a standard camera or microscope based on these metasurface pixels can directly visualize phase objects without any additional optical elements, with state-of-the-art minimum detectable phase contrasts below 10 mrad. Furthermore, the combination of sensors with equal and opposite angular response on the same pixel array can be used to perform quantitative phase imaging in a single shot, with a customized reconstruction algorithm which is also developed in this work. By virtue of its system miniaturization and measurement simplicity, the phase imaging approach enabled by these devices is particularly significant for applications involving space-constrained and portable setups (such as point-of-care imaging and endoscopy) and measurements involving freely moving objects.