Opt Express. 2023 Apr 10;31(8):12739-12755. doi: 10.1364/OE.480552.
A Fresnel Zone Aperture (FZA) mask for a lensless camera, an ultra-thin and functional computational imaging system, is beneficial because the FZA pattern makes it easy to model the imaging process and reconstruct captured images through a simple and fast deconvolution. However, diffraction causes a mismatch between the forward model used in the reconstruction and the actual imaging process, which affects the recovered image's resolution. This work theoretically analyzes the wave-optics imaging model of an FZA lensless camera and focuses on the zero points caused by diffraction in the frequency response. We propose a novel idea of image synthesis to compensate for the zero points through two different realizations based on the linear least-mean-square-error (LMSE) estimation. Results from computer simulation and optical experiments verify a nearly two-fold improvement in spatial resolution from the proposed methods compared with the conventional geometrical-optics-based method.
无透镜相机的菲涅尔区孔径（FZA）掩模是一种超轻薄的功能计算成像系统，它具有优势，因为 FZA 模式使得通过简单快速的反卷积来模拟成像过程和重建捕获的图像变得容易。然而，衍射会导致重建中使用的正向模型与实际成像过程之间不匹配，从而影响恢复图像的分辨率。这项工作从理论上分析了 FZA 无透镜相机的波动光学成像模型，并专注于频率响应中衍射引起的零点。我们提出了一种通过基于线性最小均方误差（LMSE）估计的两种不同实现来补偿零点的图像合成新方法。计算机模拟和光学实验的结果验证了与传统基于几何光学的方法相比，所提出的方法在空间分辨率上有近两倍的提高。
