CATADIOPTRIC OBJECTIVE FOR SCATTEROMETRY

摘要

inspection device, for example, is a system and method for correcting an aberration caused by the curvature of field as a catadioptric objective lens that may be used in the scattering coefficient are explained. In one embodiment, the catadioptric optical system includes a first catadioptric elements and a second catadioptric element. The first catadioptric element includes a second surface which is positioned to focus the beam reflected by the first surface and the first surface is positioned to reflect the beam. Second catadioptric element is configured to receive the beam reflected by the second reflection surface of the first refractive element. Second refractive element includes a reflection and the fourth reflective surface is positioned to focus the beam which is reflected by the third surface, and the third reflection surface that is positioned to reflect the beam. A second curvature of the third or fourth aspect of the catadioptric elements is selected so that applying a positive contribution to the curvature of field associated with a first catadioptric element. ;