INTERFEROMETRY METHODS AND SYSTEMS HAVING A COUPLED CAVITY GEOMETRY FOR USE WITH AN EXTENDED SOURCE

摘要

Interferometry methods and systems using coupled cavities and extended sources are disclosed. A main cavity (120) and a remote cavity (170) having similar optical properties are provided to compensate optical path differences (OPD) without degrading interference contrast in the image (109) of a camera (190). The remote cavity includes a stage (180) for adjusting the OPD. In one aspect the total OPD of the marginal rays is smaller than the wavelength when the total OPD of the chief rays is zero. In a further aspect the test and the reference light is coupled between the main cavity and the remote cavity with unit magnification. In another aspect two remote cavities are provided. In a further aspect a remote cavity is used to adjust a spherical portion of the optical measurement surface (150). In another aspect detachable optical assemblies are provided to form the main cavity.