Patent ID: 7616324

Claim:
An ultra-precision profile measuring method for measuring an overall profile of a measurement object by: acquiring pieces of microscopic measurement data on an area smaller than an area of a curved measurement surface of the measurement object, with an overlapping area being defined between the adjoining pieces of data, with use of a Michelson microscopic interferometer; and performing stitching while optimally correcting a tilt between the adjoining pieces of microscopic measurement data by utilizing a matching degree on the overlapping area of the adjoining pieces of microscopic measurement data, with use of overall profile data obtained with a Fizeau interferometer, the ultra-precision profile measuring method comprising: in the overall profile measurement with the Fizeau interferometer, simultaneously measuring, with the Fizeau interferometer, the curved measurement surface and a reference flat surface whose profile data is known; simultaneously and sequentially tilting the curved measurement surface and the reference flat surface with respect to a reference plane of the Fizeau interferometer to acquire pieces of partial profile data on an area smaller than the area of the curved measurement surface, with an overlapping area being defined between the adjoining pieces of data; measuring a relative angle between the adjoining pieces of partial profile data as a tilt angle of the reference flat surface; and stitching the adjoining pieces of partial profile data by utilizing a matching degree between the tilt angle and the overlapping area.