An analysis is made of the propagation of polarised light in an optica
l system which consists of a linear polariser and a liquid-crystal lay
er, of nonuniform thickness, in which the director of the molecules is
oriented along the tangents to concentric circles, It is shown that t
here is a one-to-one correspondence between the polarisation of the in
cident light and the intensity distribution at the output from this op
tical system.