Common-path lensless digital holographic microscope employing a Fresnel biprism

Abstract

Digital holographic (DH) microscopy is a nondestructive quantitative method for studying micron-sized samples with a special application in medicine, biology and materials science. Off-axis geometry of this method generates high-quality quantitative phase images employing beam-splitters, mirrors, condensers and magnifying lenses, which greatly increase the cost, size and sensitivity of the system against mechanical noise effects. The essential aim of recently proposed common-path configurations is to make viable approaches which minimize the mechanical and optical noises. Here we present a lensless DH microscopy system based on a common-path geometry using a Fresnel biprism for formation of off-axis geometry. The system comprises a lens for producing two spherical waves and by carefully choosing its parameters, we can construct a 3D imaging microscope with desired fringe spacing and overlapping region which is employed for studying many samples with different sizes, shapes and confluences. The system is compact, light-weight and robust versus mechanical vibrations. The ability to image amplitude and phase samples has been tested using standard test samples, living cells and water droplets.