title: Absolute flatness testing of skip-flat interferometry by matrix analysis in polar coordinates.
abstract: A new method utilizing matrix analysis in polar coordinates has been presented for absolute testing of skip-flat interferometry. The retrieval of the absolute profile mainly includes three steps: (1) transform the wavefront maps of the two cavity measurements into data in polar coordinates; (2) retrieve the profile of the reflective flat in polar coordinates by matrix analysis; and (3) transform the profile of the reflective flat back into data in Cartesian coordinates and retrieve the profile of the sample. Simulation of synthetic surface data has been provided, showing the capability of the approach to achieve an accuracy of the order of 0.01 nm RMS. The absolute profile can be retrieved by a set of closed mathematical formulas without polynomial fitting of wavefront maps or the iterative evaluation of an error function, making the new method more efficient for absolute testing.
authors.forename: Zhi-Gang
authors.initials: ZG
authors.lastname: Han
authors.forename: Lu
authors.initials: L
authors.lastname: Yin
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Ri-Hong
authors.initials: RH
authors.lastname: Zhu