title: Additive-Subtractive Two-Wavelength ESPI Contouring by Using a Synthetic Wavelength Phase Shift.
abstract: The addition correlation of two speckle fields by simultaneousillumination at different wavelengths is used for object contouring ina Twyman-Green-type interferometer. Fringe visibility is enhancedwhen the stochastic speckle background intensity obtained from areference plane modulation is subtracted. We calculate the contourphase map by using a phase-shift algorithm in the syntheticwavelength. A comparison with a sequential illumination, phasedifference method based on a laser wavelength phase shift isgiven. The test setup does not need to be stable on aninterferometric scale, and therefore a method is provided that lendsitself to applications in noisy environments.
authors.forename: E
authors.initials: E
authors.lastname: Hack
authors.forename: B
authors.initials: B
authors.lastname: Frei
authors.forename: R
authors.initials: R
authors.lastname: Kästle
authors.forename: U
authors.initials: U
authors.lastname: Sennhauser