Ultraprecision Fabrication of Aspherical Reference Mirrors for Interferometry

摘要

This paper proposes a new aspherical interferometric measuring method, in which an aspherical mirror is used for reference. Compared with the aspherical master which has few profile errors from the ideal shape, the aspherical reference mirror made by the fly-cutting of oxygen free copper has some profile errors which enable the observation of interferometric fringes. However the accurate profile of the reference needs to be evaluated by a more accurate measuring instrument. The combination of the profile of the aspherical reference and the interferometric fringe pattern enables the evaluation of the shape of the measured object. An interferometric measurement of a toroidal surface was conducted with a Fizeau interferometer and this aspherical reference mirror. Interferometric fringes were observed on almost the whole surface of the measured object.