METHOD AND DEVICE FOR INTERFEROMETRIC MEASURING OF SHAPE DEVIATION OF OPTICAL SURFACES

FIELD: measuring engineering. ^ SUBSTANCE: method comprises directing a coherent light beam at the surface to be tested, producing and recording interferogram of the light path difference, and processing the interferogram. The tested and reference surfaces are exposed to the second coherent light beam, and the second interferogram of the light path difference is created. The second interferogram is provided with the additional light path difference with respect to that of the first interferogram, which is equal to the one fourth of the beam wavelength. The light path difference of the first interferogram is determined at specific points of the surface to be tested from the signal of illumination in one of two interferograms. The device comprises source of coherent light, first filter-condenser, first and second light-splitting units, interferometer composed of tested and reference surfaces, unit for measuring optical length of the beam, first projecting unit, recording unit, observing unit, and unit for processing the interferogram. The device also has two light-splitting units between which two pairs of transparent diffraction lattices are interposed. The filter-condenser, the second light-splitting unit, and lambda/4 lattice are arranged in series in the direction of the beam. ^ EFFECT: enhanced precision. ^ 4 cl, 8 dwg