title: Large radius of curvature measurement based on virtual quadratic Newton rings phase-shifting moiré-fringes measurement method in a nonnull interferometer.
abstract: We have proposed a virtual quadratic Newton rings phase-shifting moiré-fringes measurement method in a nonnull interferometer to measure the large radius of curvature for a spherical surface. In a quadratic polar coordinate system, linear carrier testing Newton rings interferogram and virtual Newton rings interferogram form the moiré fringes. It is possible to retrieve the wavefront difference data between the testing and standard spherical surface from the moiré fringes after low-pass filtering. Based on the wavefront difference data, we deduced a precise formula to calculate the radius of curvature in the quadratic polar coordinate system. We calculated the retrace error in the nonnull interferometer using the multi-configuration model of the nonnull interferometric system in ZEMAX. Our experimental results indicate that the measurement accuracy is better than 0.18% for a spherical mirror with a radius of curvature of 41,400 mm.
authors.forename: Zhongming
authors.initials: Z
authors.lastname: Yang
authors.forename: Kailiang
authors.initials: K
authors.lastname: Wang
authors.forename: Jinlong
authors.initials: J
authors.lastname: Cheng
authors.forename: Zhishan
authors.initials: Z
authors.lastname: Gao
authors.forename: Qun
authors.initials: Q
authors.lastname: Yuan