title: Phase effects in double-focus and double-aperture interference microscopy.
abstract: Two different optical techniques for surface tracking and linewidth measurement are evaluated. First, an evaluation is made of the performance of a double-focus polarization microscope, based on results from a computer model and from experimental measurements. The assessment shows that a phase curvature effect makes the operation of this configuration impractical as a surface tracking device and linewidth measurement system. An alternative arrangement of using a double aperture is evaluated. The phase curvature effect is reduced in this type of microscope. A practical optical arrangement to implement a double-aperture microscope is given.
authors.forename: S A
authors.initials: SA
authors.lastname: Barman
authors.forename: J G
authors.initials: JG
authors.lastname: Walker
authors.forename: J W
authors.initials: JW
authors.lastname: Nunn
authors.forename: N P
authors.initials: NP
authors.lastname: Turner
authors.forename: M J
authors.initials: MJ
authors.lastname: Downs