Phase effects in double-focus and double-aperture interference microscopy

Two different optical techniques for surface tracking and linewidth measure ment are evaluated. First, an evaluation is made of the performance of a do uble-focus polarization microscope, based on results from a computer model and from experimental measurements. The assessment shows that a phase curva ture effect makes the operation of this configuration impractical as a surf ace tracking device and linewidth measurement system. An alternative arrang ement of using a double aperture is evaluated. The phase curvature effect i s reduced in this type of microscope. A practical optical arrangement to im plement a double-aperture microscope is given. (C) 2000 Optical Society of America.