Polarising beam splitter e.g. for differential measurements

摘要

The beam splitter includes two Wollaston prism which split an unpolarised incident ray of light into two rays of light, vertically linearly polarised with respect to each other. The splitting consists in a change of direction of the exiting rays with respect to the incident ray, and is symmetrical. Both existing rays undergo a directional change with respect to an angle of the incident ray, which is equal for both, but with opposed polarities. The angle under which the exiting rays are split is independent of the wavelength of the light. The ray splitting of a normal Wollaston prism, which depends on the lights wavelength, is compensated by using two Wollaston prisms, which are put together from different crystals with accordingly different dispersions, in such way, that the resulting splitting angle of the combination is independent of the lights wavelength.