Patent ID: 9267789
Filing Date: 2016-02-23
CPC Classification: G01B

Claim Text:
1. A method for absolute measurement of flatness of surfaces of optical elements, comprising: using an interferometer having a measurement axis and including a reference surface position and a test surface position for applying a three-flat method to three optical elements, by conducting actual measurements on the three optical elements, the actual measurements respectively providing interferograms; and reconstructing respective planes of the three optical elements by an iterative processing operation in which the actual measurements are mathematically simulated and simulated measurements are compared with the actual measurements; wherein each actual measurement is carried out by placing the respective surfaces of two of the three optical elements facing each other, respectively in a reference surface position and in a test surface position, and wherein at least one of the actual measurements is made after having performed a rotation around the measurement axis, and another actual measurement is made after having performed a translation perpendicular to the measurement axis of one of the two optical elements relative to the other.