Abstract

Interferometric tests of convex surfaces for large N. A. lens systems often present serious problems. These surfaces can be tested quite simply by making use of the aplanatic imaging properties of a spherical surface. Using a Fizeau interferometer, the reference surface N.A. is chosen so that the surface under test can be filled when the beam from the interferometer is directed to converge on the further aplanatic point of the test surface. Refraction will direct the beam to the closer aplanatic point. After the beam is reflected back from the closer aplantic point, the rays will be normal to the reference surface of the interferometer if the test surface is perfect. To perform this test, the test lens needs to have a thickness so that the back surface is at the closer aplanatic point.

© 1991 Optical Society of America