近日，美国加州大学的Aydogan Ozcan及其研究团队取得一项新进展。经过不懈努力，他们使用衍射处理器实现全光学复场成像。相关研究成果已于2024年5月28日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队提出了一个复杂的场成像仪设计，其使用基于强度的传感器阵列，无需任何数字处理，即可对输入场的幅度和定量相位信息进行快照成像。这一设计利用连续的深度学习优化的衍射表面，其结构可以共同调制输入复杂场，形成两个独立的成像通道，在紧凑的光学设计中，在输入和输出平面之间执行幅度到幅度和相位到强度的转换，轴向跨越约100个波长。

这两个通道的输出场在传感器平面上的强度分布，直接对应于输入复杂场的振幅和定量相位分布，无需任何数字图像重建算法。研究人员通过实验验证了该复杂场衍射成像仪设计的有效性，通过3D打印原型在太赫兹频谱下工作，输出幅度和相位通道图像与我们的数值模拟紧密一致。他们设想这种复杂的现场成像仪将在安全、生物医学成像、传感和材料科学等领域有各种应用。

据悉，复杂场成像可以捕获输入光场或物体的振幅和相位信息，可以为样品提供丰富的结构信息，例如它们的吸收和折射率分布。然而，传统的图像传感器是基于强度的，固有地缺乏直接测量场的相位分布的能力。为了克服这种限制，可以采用干涉或全息方法，并辅以迭代相位检索算法。然而，这种方法通常会导致硬件复杂性和计算需求的显著增加。

附：英文原文

Title: All-optical complex field imaging using diffractive processors

Author: Li, Jingxi, Li, Yuhang, Gan, Tianyi, Shen, Che-Yung, Jarrahi, Mona, Ozcan, Aydogan

Issue&Volume: 2024-05-28

Abstract: Complex field imaging, which captures both the amplitude and phase information of input optical fields or objects, can offer rich structural insights into samples, such as their absorption and refractive index distributions. However, conventional image sensors are intensity-based and inherently lack the capability to directly measure the phase distribution of a field. This limitation can be overcome using interferometric or holographic methods, often supplemented by iterative phase retrieval algorithms, leading to a considerable increase in hardware complexity and computational demand. Here, we present a complex field imager design that enables snapshot imaging of both the amplitude and quantitative phase information of input fields using an intensity-based sensor array without any digital processing. Our design utilizes successive deep learning-optimized diffractive surfaces that are structured to collectively modulate the input complex field, forming two independent imaging channels that perform amplitude-to-amplitude and phase-to-intensity transformations between the input and output planes within a compact optical design, axially spanning ~100 wavelengths. The intensity distributions of the output fields at these two channels on the sensor plane directly correspond to the amplitude and quantitative phase profiles of the input complex field, eliminating the need for any digital image reconstruction algorithms. We experimentally validated the efficacy of our complex field diffractive imager designs through 3D-printed prototypes operating at the terahertz spectrum, with the output amplitude and phase channel images closely aligning with our numerical simulations. We envision that this complex field imager will have various applications in security, biomedical imaging, sensing and material science, among others.

DOI: 10.1038/s41377-024-01482-6

Source: https://www.nature.com/articles/s41377-024-01482-6