Method and apparatus for real-time determination of curvature and azimuthal asymmetry of a surface

摘要

An apparatus for measuring a curvature of a surface (1), comprising means for irradiating a first light beam (S1), a second light beam (S2) and a third light beam (S3) onto a surface (1) of a sample (12), a detector (5) comprising at least one detector plane and being adapted to detect a first position of the reflected first light beam (S1), a second position of the reflected second light beam (S2) and a third position of the reflected third light beam (S3) in the at least one detector plane, means for determining a first distance between the first position of the first light beam (S1) and the third position of the third light beam (S3) and a second distance between the second position of the second light beam (S2) and the third position of the third light beam (S3), and means for determining a mean curvature of the surface from the first distance and the second distance. The first light beam (S1), the second light beam (S2) and the third light beam (S3) are parallel to each other and the first light beam (S1) is spaced apart from a plane defined be the second light beam (S2) and the third light beam (S3).