INTERFERENCE MEASURING DEVICE AND INTERFERENCE MEASUREMENT METHOD

PROBLEM TO BE SOLVED: To reduce an error in transmission wave front measurement of a lens body, by separating an interference fringe on a planar part of a lens from an interference fringe on the lens body. SOLUTION: This interference measuring device 1, for measuring the transmission wave front of the lens having the lens body and the planar part 16, is equipped with a first light source 2 for generating an inspection light B1 having the same wavelength as a design wavelength of the lens, a second light source 3 for generating alignment light B2 having a wavelength different from that of the inspection light B1, a main beam splitter 4 for splitting the inspection light B1 and the alignment light B2 into reference light and light to be inspected; a spherical mirror 6 for reflecting the light to be inspected; a correction plate 17 provided between the spherical mirror 6 and the main beam splitter 4; a placing table 14 for installing the lens thereon; and a planar mirror 5 for reflecting the reference light. A coherent distance of the inspection light B1 is shorter than a design optical path difference determined, based on an optical parameter including a design parameter of the lens, and the coherence length of the alignment light B2 is larger than the design optical path difference. COPYRIGHT: (C)2008,JPO&INPIT