Lensless LED matrix ptychographic microscope: problems and solutions

In this paper, a lensless microscope based on ptychography is presented. It disposes of the mechanic movement necessary for conventional ptychography, instead using an LED matrix to obtain a diverse set of diffraction data. This data is subject to multiple experimental factors that deviate from the standard version of ptychography: namely, imprecise knowledge of the LED positions, partial temporal and spatial coherence, and varying brightness and illumination distribution between individual LEDs. Despite these difficulties, we show here that the diversity in the ptychographic data allows an iterative phase retrieval algorithm to recover excellent, high-resolution images of a resolution test target and a biological sample. (C) 2018 Optical Society of America