tilted-use object waves and a Fizeau interferometer exhibiting Interferometerobjektiv

is presented to an interferometer for dimensional measurement of an optically smooth surface, having means for illuminating a surface portion with a plurality of discrete object waves from different directions, and with means which on the surface reflected object waves of several object waves coherent reference wave on a detector to an interferogram superimpose , the interferometer is characterized in that it is adapted to illuminate the surface simultaneously with a plurality of object waves and generate the reference waveform by a Fizeau beam splitter plate or a Fizeau lens, and that the interferometer is a (in the beam path in front of the detector 14 ) arranged Interferometerblende (12) and imaging optics, wherein the Interferometerblende something is in or outside the Fourier plane of the imaging optics and the light reflected from the surface of object waves filters. An independent claim is directed to a method for measuring a planar optically smooth surface.