Device for optically measuring the height of a surface

A device for optically measuring the height of a surface of an object, which device comprises a radiation source unit for generating a radiation beam and for forming an essentially stationary radiation spot on the surface by means of said beam, means for selecting a reflected beam from the radiation reflected on the surface in the radiation spot, and a first position-sensitive radiation detection system arranged in the radiation path of the reflected beam, characterized in that a beam splitter for splitting-off a sub-beam is arranged in the radiation path of the reflected beam and in that a second position-sensitive radiation detection system whose optical distance to the beam splitter differs from the optical distance between the first position-sensitive radiation detection system and the beam splitter is arranged in the radiation path of said sub-beam, both position-sensitive radiation detection systems being for determining the location of the same characteristic point of the radiation distribution on each detection system, the combination of both systems being indicative of the height of the surface.