New paper in Optics Letters, Vol. 40, Issue 10, pp. 2273-2276, 2015:

Off-axis interferometer with adjustable fringe contrast based on polarization encoding

Sharon Karepov, Natan T. Shaked, and Tal Ellenbogen

Abstract: We propose a compact, close-to-common-path, off-axis interferometric system for low polarizing samples based on a spatial polarization encoder that is placed at the Fourier plane of a conventional transmission microscope. The polarization encoder erases the sample information from one polarization state and maintains it on the orthogonal polarization state, while retaining the low spatial frequencies of the sample, and thus enabling quantitative phase acquisition. In addition, the interference fringe visibility can be controlled by polarization manipulations. We demonstrate this concept experimentally by quantitative phase imaging of a USAF 1951 phase test target and human red blood cells with optimal fringe visibility and single-exposure phase reconstruction.

[PDF] [Link]

Imaging of USAF 1951 phase test target using the polarization encoding interferometer. (a) Intensity image with co-polarized analyzer (at 90°), associated with the sample arm, and (b) with cross-polarized analyzer (at 0°), associated with the reference arm. (c) The off-axis interference obtained on a small area of the background. (d) The reconstructed quantitative phase map. Scale bars are 26.7 μm in (a), (b) and (d), and 6.8 μm in (c).