SEPARATION OF PHASE AND ABSORPTION IMAGES IN PHASE-CONTRAST MICROSCOPY

A method for separating the phase distribution from the image of a semitransparent sample observed with a phase-contrast microscope is proposed. Three images of the same sample are used for calculating the phase distribution, one observed by a normal objective lens and the others observed by a bright-contrast objective and a dark-contrast objective. The method works even for samples that are not weak phase objects. The phase (or refractive-index) distribution is quantitatively reconstructed by numerically solving a set of linear equations for every pixel of the sample image. The method of phase reconstruction is mathematically derived and is explained with graphs in the complex amplitude space. Experimental results are also presented.