Fast and robust misalignment correction of Fourier ptychographic microscopy

Fourier ptychographi cmicroscopy(FPM) is a newly developed computational imaging technique that can provide gigapixel images with both high resolution (HR) and wide field of view (FOV). However, the positional misalignment of the LED array induces a degradation of the reconstruction, especially in the regions away from the optical axis. In this paper, we propose a robust and fast method to correct the LED misalignment of FPM, termed as misalignment correction for FPM (mcFPM). Although different regions in the FOV have different sensitivity to the LED misalignment, the experimental results show that mcFPM is robust to eliminate the degradation in each region. Compared with the state-of-the-art methods, mcFPM is much faster.

Exploit imaging through opaque wall via deep learning

Imaging through scattering media is encountered in many disciplines or sciences, ranging from biology, mesescopic physics and astronomy. But it is still a big challenge because light suffers from multiple scattering is such media and can be totally decorrelated. Here, we propose a deep-learning-based method that can retrieve the image of a target behind a thick scattering medium. The method uses a trained deep neural network to fit the way of mapping of objects at one side of a thick scattering medium to the corresponding speckle patterns observed at the other side. For demonstration, we retrieve the images of a set of objects hidden behind a 3mm thick white polystyrene slab, the optical depth of which is 13.4 times of the scattering mean free path. Our work opens up a new way to tackle the longstanding challenge by using the technique of deep learning.

Analysis of the noise in back-projection light field acquisition and its optimization

Light field reconstruction from images captured by focal plane sweeping can achieve high lateral resolution comparable to the modern camera sensor. This is impossible for the conventional micro-lenslet based light field capture systems. However, the severe defocus noise and the low depth resolution limit its applications. In this paper, we analyze the defocus noise and the depth resolution in the focal plane sweeping based light field reconstruction technique, and propose a method to reduce the defocus noise and improve the depth resolution. Both numerical and experimental results verify the proposed method.