title: Subtractive two-frame three-beam phase-stepping interferometry for testing surface shape of quasi-parallel plates.
abstract: We present an effective method of testing the surface shape of quasi-parallel plates which requires only two phase-shifted three-beam interferograms. We derive a general formula for difference of two three-beam interferograms as a function of the phase shift value. The phase shift does not have to be precisely determined and uniform in the image domain. We show and compare results of extracting the fringe set and corresponding phase distribution related to the plate front surface shape using the two dimensional continuous wavelet transform, Hilbert-Huang transform and Fourier transform methods. Simulated and experimental data is used to verify the algorithm performance and robustness.
authors.forename: Zofia
authors.initials: Z
authors.lastname: Sunderland
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Patorski
authors.forename: Maciej
authors.initials: M
authors.lastname: Trusiak