Dual-wavelength phase imaging for lensless digital holographic microscopy with a filter

Abstract

We present a simple and effective method for dual-wavelength phase imaging in lensless reflection digital holographic microscopy (LRDHM). A filter is inserted between beam splitter and mirror in LRDHM. By adjusting the filter and mirror, the propagation directions of two reference beams of different wavelengths can be separated, and thus two off axis holograms with different fringe directions are simultaneously captured by a monochrome camera. Our scheme is available for real-time dual-wavelength phase imaging but requires minimum optical element and system modification for LRDHM. A series of simulations on wavefront interference analysis for using a filter is discussed in detail. We demonstrate the validity of proposed method with a step target.