Interferometer using tilted object waves and comprising a fizeau interferometer objective

Interferometer for areally measuring an optically smooth surface, comprising means for illuminating a surface region, to be measured, of the surface with a plurality of object waves from different directions, and means which, on a detector, superimpose object waves reflected at the surface onto a reference wave that is coherent with a plurality of object waves in order to form an interferogram in which dimensions of the surface are imaged, the interferometer being configured to illuminate the surface with a plurality of object waves at the same time and produce the reference wave by way of a Fizeau beam splitter plate or a Fizeau objective, and thus by means of beam splitting from one of the object waves that illuminate the surface, the interferometer comprising an interferometer stop that is arranged within the beam path upstream of the detector, and imaging optics, the interferometer stop being situated within, or slightly outside of, the Fourier plane of the imaging optics and said interferometer stop filtering the object waves reflected by the surface, characterized in that the interferometer has a rigid arrangement of switchable point light sources as the illumination means, in that the interferometer is designed to illuminate the optically smooth surface, during the measurement thereof, with different samples of mutually differing object waves, each sample producing its own reference wave that is deactivated when illumination with a different sample occurs, and in that these point light sources and the interferometer stop are designed such that, for each measured value recording, just one reference wave front reaches the detector and completely illuminates said detector.