Interferometric measuring arrangement for sensing rough surfaces

摘要

The invention relates to an interferometric measuring device for measuring form on rough surfaces of an object, comprising a unit for producing a beam, said unit emitting a short-coherent beam and a beam-splitting device for producing a reference beam which is directed onto a device with a reflective element for periodically altering the path of light and a measuring beam which is directed onto the object. The inventive device also has a superimposition element on which the measuring beam coming from the object and the reference beam coming from the device are caused to interfere, and a photo sensor for recording the interfered beam. The invention provides a simple construction which nonetheless guarantees highly accurate measuring. The device for altering the light path has a parallel displacement system which is positioned in the path of the beam, the reflective element being placed in a fixed position behind said parallel displacement system. A compensation grating is also located in the path of the reference beam, in front of the parallel displacement system. The reference beam is diffracted on said compensation grating both before and after passing through the parallel displacement device.