Simultaneous measurement of refractive index distribution and topography by integrated transmission and reflection digital holographic microscopy

We propose a method for simultaneously measuring dynamic changes of the refractive index distribution and surface topography, which integrates the transmission and reflection digital holographic microscopy based on polarization and angular multiplexing techniques. The complex amplitudes of the transmitted and reflected object waves can be simultaneously retrieved. The phase information of the reflected object wave is directly used to determine the topography of the specimen which corresponds to its physical thickness. Assuming that the refractive index distribution is uniform in the direction of the specimen thickness, the refractive index distribution can be deduced from the phase distributions of the transmitted and reflected object waves without any approximation. The refractive index distribution and dynamic changes of the topography of a tiny deionized water droplet have been measured for the availability of the proposed method.