The theory for interferometric analysis of an arbitrarily oriented birefringent sample is developed. The object is placed in one of the arms of a Mach-Zehnder Interferometer. Interferograms are recorded for vertically and horizontally polarized light passing through the sample. The spatial phase information for these two cases is suitably combined through an algorithm developed for this purpose to yield the complete spatial distribution of retardance and direction of birefringence over the sample plane. The proposed method is able to measure spatial variations of birefringence from 0 to π and is targeted to measurement of low birefringence as in biological specimens. Simulation results presented validate the proposed theory. Experimental results are forthcoming. © Springer Nature Singapore Pte Ltd. 2017.