A device capable of measuring small displacements ~nd vibrati~ns o~ a n:oving body is .presented. A small mirror, firmly attached to the object unde~ mv.eStlgatlOn, defiect~ a paIr ~~laser beams onto two distinct photodetectors. From the exammahon of the output SIgnals, It IS possible to have separate information on the rotational and translational movements of a surface
