Depolarizer, telescope and remote sensing device and method

A light beam is applied to a front surface of an optical depolarizer. The depolarizer rotates the polarization of light received on different surface positions by different amounts, so that the average incoming polarization is scrambled. The depolarizer has a first and second body that transmit first and second polarization components of the beam with mutually different speeds of light. Each body has two wedge shaped parts of variable thickness, corresponding wedge shaped parts in the two bodies providing light paths of substantially position independent lengths, but with variable rotation of polarization. The wedge shape parts of the front body form a concave input surface for the incoming beam. This prevents cross-over of light between the different wedge shaped parts.