Lensless on-chip LED array microscope using amplitude and phase masks

Abstract

A cost-effective, compact, and portable optical system using multi-angle illumination for retrieval of the amplitude and phase of a sample is implemented in this paper. The system consists of a matrix of LED followed by a mask, a USAF resolution chart, and a detector in a column. The sample information is collected by the detector directly without any objective lens. The sample information is encoded by the mask at a sensor plane during the reconstruction process. To retrieve the sample information from captured raw images corresponding to each LED illumination, the backward propagation model is applied. Three types of masks are used: a phase mask having pixel values from 0 to 2 π , an amplitude mask, and a combination of a phase and an amplitude mask with random distribution. The applications of such type of technique are most common in biomedical engineering for infection diagnostic purposes. In the future, the commercial demand of such lensless microscope would be high due to its simplicity and fast image processing capacity.