Synthetic aperture phase-shifting interferometry for high numerical- aperture spherical surface measurement

摘要

We propose a synthesis of phase-shifting algorithms for Fizeau interferometry of high numerical-aperture spherical surfaces. Several approaches have been reported for spherical surface measurements such as phase shifting, carrier fringe, and wavelength tuning. The commonly used method of phase shifting with mechanical phase modulation suffers from spatial nonuniformity of the phase step within the observing aperture. We operated seven algorithms designed for different phase steps on the same set of interference fringes recorded in a one phase-shift sequence, and determined the object phase from each of the algorithms depending on the aperture position. The resultant phase distribution showed minimum systematic errors.