Yoichi Iba

Fringe contrast improvement in Twyman-Green interferometer for lens test

With respect to the cases of observing the wavefronts passing through a lens, studies were made for improving the fringe contrast from both aspects, temporal coherence and spatial coherence, of the light sources of interferometers. Experiments based on the studies also were done, employing an excimer laser and a projection lens as the light source of a Twyman-Green interferometer and the lens under test, respectively, which the experiments showed had preferable results. There is, however, a possible problem which could occur if the lens under test is not corrected for chromatic aberration.