title: Compensation for correlated error in multilayer interferometer.
abstract: Wavelength tuning interferometry is used to measure and estimate the surface shape of a sample. However, in multilayer interferometry (e.g., a lithium niobate [LNB] crystal wafer attached to a supporting plate), the correlated error between the higher harmonics and the phase-shift error causes considerable error in the calculated phase. In this study, the correlated errors calculated by various types of windowed phase-shifting algorithms are analyzed in connection with the characteristic polynomial theory and Fourier representation of the algorithms. The surface shape and optical thickness variation of the LNB wafer are measured simultaneously using the windowed phase-shifting algorithms. The results are compared in terms of the observed ripples and measurement repeatability. The experimental results show that the 4N-3 algorithm is optimal and possesses the smallest repeatability error.
authors.forename: Yangjin
authors.initials: Y
authors.lastname: Kim
authors.forename: Kenichi
authors.initials: K
authors.lastname: Hibino
authors.forename: Naohiko
authors.initials: N
authors.lastname: Sugita
authors.forename: Mamoru
authors.initials: M
authors.lastname: Mitsuishi