External beam delivery system for laser dark-field illumination in a catadioptric optical system

摘要

A catadioptric objective configured to inspect a specimen is provided. The catadioptric objective includes a Mangin element having one surface at a first axial location and an extension element positioned together with the Mangin element. The extension element provides a second surface at a second axial location. Certain light energy reflected from the specimen passes to the second surface of the extension element, the Mangin element, and through a plurality of lenses. An aspheric surface may be provided, and light energy may be provided to the specimen using diverting elements such as prisms or reflective surfaces.

主权项

1. A specimen inspection apparatus, comprising:
a light energy source; at least one lens; and a composite Mangin element comprising a first surface axially positioned away from the specimen and a second surface axially positioned toward the specimen and an extension comprising a third surface axially positioned closer to the specimen than the second surface; wherein the light energy source is configured to transmit light energy substantially parallel to a surface of the specimen, and the apparatus is further configured to divert light energy around the extension of the composite Mangin element, thereby striking the surface of the specimen, and further wherein certain light energy reflected from the specimen passes through the third surface, second surface, first surface, and at least one lens.