Label-free color staining of quantitative phase images

Abstract

Phase contrast microscopy enables the label-free visualization of “phase-only” objects such as unstained biological cells. This approach produces a contrast in image intensity that relates qualitatively to the phase delay introduced by the specimen. Quantitative phase imaging refers to an emerging set of methods that naturally extend phase contrast microscopy. These methods enable the quantitative measurement of the phase delay introduced by the specimen, which facilitates real-time measurement of cellular morphology with nanometric resolution in the axial direction. In this paper, we describe a simple, efficient algorithm that produces a color image from the quantitative phase image, which clearly highlights subcellular features. The approach is interpreted in terms of local spatial-frequency with the aid of microlens array and results are presented for a range of diatom cells.