Yang Chen, Ni Cong, Zhang Xinye, Li Yusen, Zhai Yusheng, He Weiji, Zhang Wenwen, Chen Qian
Opt Express. 2024 Mar 25;32(7):11323-11336. doi: 10.1364/OE.519871.
The lensless camera with incoherent illumination has gained significant research interest for its thin and flexible structure. However, it faces challenges in resolving scenes with a wide depth of field (DoF) due to its depth-dependent point spread function (PSF). In this paper, we present a single-shot method for extending the DoF in Fresnel zone aperture (FZA) cameras at visible wavelengths through passive depth estimation. The improved ternary search method is utilized to determine the depth of targets rapidly by evaluating the sharpness of the back propagation reconstruction. Based on the depth estimation results, a set of reconstructed images focused on targets at varying depths are derived from the encoded image. After that, the DoF is extended through focus stacking. The experimental results demonstrate an 8-fold increase compared with the calibrated DoF at 130 mm depth. Moreover, our depth estimation method is five times faster than the traversal method, while maintaining the same level of accuracy. The proposed method facilitates the development of lensless imaging in practical applications such as photography, microscopy, and surveillance.
具有非相干照明的无透镜相机因其薄且灵活的结构而受到了广泛的研究关注。然而，由于其与深度相关的点扩散函数（PSF），它在解析具有宽景深（DoF）的场景时面临挑战。在本文中，我们提出了一种单镜头方法，通过被动深度估计在可见波长下扩展菲涅尔区孔径（FZA）相机的景深。利用改进的三分搜索法，通过评估反向传播重建的清晰度来快速确定目标的深度。基于深度估计结果，从编码图像中导出一组聚焦于不同深度目标的重建图像。之后，通过焦点堆叠扩展景深。实验结果表明，在130毫米深度处，与校准景深相比增加了8倍。此外，我们的深度估计方法比遍历方法快五倍，同时保持相同的精度水平。所提出的方法有助于无透镜成像在摄影、显微镜和监视等实际应用中的发展。
