Polarimeters and Spectropolarimeters. The Measurement of Optical Activity

Abstract

Ordinary light coming from the sun or a lamp is polychromatic,i.e. of different wavelengths, and the waves oscillate in different planes perpendicular to the direction of propagation. A monochromator separates the waves of certain definite length from the polychromatic multitude. A polarizer separates out the waves which oscillate only in one plane. A monochromatic unpolarized ray can be compared with a bottle brush in which the bristles point out in various directions, and a polarizer works like a slicer cutting off the bristles at the sides, leaving only those which point “up” and “down”. Since the uniformity of the light is achieved not by “transforming” but by separation, the polarized beam is always of lesser intensity than that generated by a source.