APPARATUS FOR MEASURING RADIUS OF CURVATURE OF OPTICAL SPHERICAL SURFACE

摘要

PROBLEM TO BE SOLVED: To measure the radius of curvature of an optical spherical surface with accuracy of a submicron order and by means of a compact and simple device constitution by employing the idea of techniques for measuring steps in a plane while using a variable wavelength laser as a light source, and adopting a cat's-eye technique.;SOLUTION: This apparatus comprises a source 1 of variable wavelength laser beams, a half prism 20, a collimator lens 6, a second reference lens 5R causing the laser beam to impinge on the reference surface 5a (concave spherical surface) of the first reference lens 5F of a reference lens portion 5 at approximately right angles so that the laser beam exits the reference surface 5a at approximately right angles, a reflector 7 having a reflecting plane at the focal position of the second reference lens 5R, a light intensity detecting means 9 for detecting the intensity of light interference occurring between the laser beam LA normally reflected by the reflecting plane and the laser beam LB coming from the source 1 and reflected at a position 5b where it re-impinges on the reference surface 5a at right angles, a Fourier transform means 10 for measuring the frequency n of variation in light intensity through a Fourier transform, and a radius-of-curvature calculating means 11 for calculating the radius of curvature R of the reference surface 5a on the basis of the frequency n.;COPYRIGHT: (C)2001,JPO