| 摘要 |
Invention concerns a method and corresponding apparatus for interferometrically determining a radius of curvature rx of a curved surface (4a) of a test surface object. The method comprises known in the art steps: step of positioning the test surface relative to a reference surface of reference surface object, along the optical path, step of illuminating reference surface object and test surface object with a substantially monochromatic light beam from the first light source, along the optical path, step of moving the reference surface object and test surface object until confocal position of reference surface and test surface is detected, step of determining radius of curvature of the test surface from position of the test surface object. In the method according to the invention, as opposed to the state of the art, the step of determining radius of curvature of the test surface from position of the test surface object consists in determining the radius of curvature of the test surface from the radius of curvature rr of the reference surface and the distance d between the reference surface object and test surface object. The distance d between the test surface object and reference surface object is determined in following steps: illuminating the optical system with a broadband measuring- light ray along the measurement optical path, while delivering the portion of this broadband measuring-light to the reference optical path having tunable length, superimposing light beams reflected from the reference surface and test surface with the light propagating along the reference optical path, tuning the length of the reference optical path and observing superimposition of the light to detect at least two interference patterns each corresponding either to condition that length of optical path of light reflected from the reference surface is equal to the length of reference optical path or to condition that length of optical path of light reflected from the reference surface is equal to the length of reference optical path, determining the distance d from the difference of length of tuned reference optical path corresponding to both conditions. |
