A method of determining induced change of polarization state of light in a polarization element comprising transmitting unpolarized light from a light source at the one end of an optical transmitter waveguide means (21) t o polarizer means (31) at the other end; polarizing the unpolarized light by t he polarizer means (31); transmitting the polarized light through the polariza- tion element (41; 41A, 41B) using at least one reflective optical element; a n- alyzing the transmitted polarized light from the polarization element by an analyzer means (32); and transmitting he analysed polarized light from the one end of optical receiver waveguide means (22) to a light detector at the other end; wherein the unpolarized light polarized by the polarizer means (31); the polarized light analysed by he analyzer means (32), or both, are non-collimated; and the polarized light in the light path between the polari z- er means (31) and the analyzer means (32) is collected and reflected by at least one reflective imaging opt
