STABILITY OF A LATERAL-SHEARING HETERODYNE TWYMAN-GREEN INTERFEROMETER

A lateral-shearing heterodyne Twyman-Green interferometer was constructed to test lenses in transmission. The goal was to determine the repeatability of the measurement of the phase of the wavefront produced by the lens. A second interferometer was used to monitor the phase modulation used in the heterodyne scheme. The wavefront map was computed by a generalized least-squares procedure. Measured phase stabilities were better than 1 m lambda .