Principle and analysis of a birefringent beam splitter

A method to extend the field of view of Savart ploariscope is presented in this paper. By using a combination of Savart polariscope and a pair of uniaxial crystal plates cut parallel to the optic axis which are fabricated from birefringent materials with opposite sign relative to that of SP with their principle sections perpendicular to each other, the useful field of view to void distortions of interference fringes can be increased by a large amount in broad spectral coverage. Compared to the combination of two Savart polariscopes, the optical path difference is higher by one order in magnitude. To demonstrate the effectiveness, a design example operating at 480–960 nm with a large solid angle exceeding ±30° is presented in detail.