The present invention relates to an arrangement for measuring relative movement. The measuring arrangement comprises a light source (110, 210) for emitting a light beam, a moving element (120, 220) having a reflective surface (121, 221) adapted to reflect a first wavefront portion of the light beam, and a reference element (130, 230) having a reflective surface (131, 231) adapted to reflect a second wavefront portion of the light beam. The arrangement further comprises detecting means (140, 240) for detecting changes in a spatial interference pattern produced by the light reflected from the moving element and the reference element, and processing means (150, 160, 250, 260) for calculating the relative movement between the moving element and the reference element from the phase change in the detected spatial interference pattern. The invention also relates to a method for measuring relative movement.