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To measure the shape of the cornea and its declinations from the necessary values before and after PRK operation, as well as the shape of other spherical objects like artificial pupil, a technique was used of doublefrequency dual-beam interferometry. The technique is based on determination of the optical path difference between two neighboring laser beams, reflected from the cornea or other surface under investigation. Knowing the distance between the beams on the investigated surface, the path difference measurement permits to get the derivative of the function describing the investigated shape. The shape itself is reconstructed by along-line integration. To adjust the wavefront orientation of the laser beam to the spherical shape of the cornea or artificial pupil in the course of scanning, additional lens is involved. Signal-to-noise ratio is ameliorated excluding losses in the acoustooptic deflectors. Polarization selection is realized for choosing the signal needed for measurement. 2D image presentation is accompanied by convenient PC accessories, permitting precise cross-section measurements along selected directions. Sensitivity of the order of 102 is achieved.