Liquid-crystal analyser of the state of polarisation of light

An analysis is made of the propagation of polarised light in an optical system which consists of a linear polariser and a liquid — crystallayer, of nonuniform thickness, of a liquid crystal in which the director of the molecules is oriented along the tangents to concentric circles. It is shown that there is a one-to-one correspondence between the polarisation of the incident light in the intensity distribution at the output from this optical system.