Experimental analysis and designing strategies of lens-less microscopy with partially coherent illumination

Abstract Lens-less microscopy can achieve a wide field of view imaging (FOV) through a simple configuration compared to conventional microscopy, and it is very attractive in resource-limited areas because of its cost-effectiveness and portability. Featuring a small package and cheapness, LEDs and LDs both show the potential to act as a reasonable illumination source for lens-less microscopes, especially for portable ones. However, based on holographic theorem, the complex light-field reconstruction algorithms consider the light source as a highly coherent one, while both LEDs and LDs can only provide partially coherent illumination. In this manuscript, we would systematically and experimentally analyze the imaging performances of lens-less microscopy with partially coherent illumination. The analysis covers autofocusing under LED/LD illumination, imaging performances under different LED spatial coherence and imaging performances under LED/LD illumination. Furthermore, based on the analysis, some conclusions about designing a lens-less microscope are presented. We think that the experiments and conclusions can provide effective guidance to construct a low-cost lens-less microscope with trade-off hardware parameters in practices.