Radius radius measurement using spectrally controlled interferometry

摘要

The ROC value of a test surface (14) is measured with a single spectrally controlled interferometric measurement using a reference source (18) with known ROC. The test surface is placed at the confocal position (24) of the reference surface and the light source (16) is modulated to create localized lines of interference (30-34, 36-40, 42-46) at the location of the test surface. The interference lines are then processed with conventional interferometric analysis tools to determine the exact position of the test surface with respect to the reference surface, thereby determining the distance between the test surface and the reference surface. The radius of curvature of the test surface is obtained simply by subtracting such a distance from the known radius of curvature of the reference surface.