Patent ID: 6862090
Filing Date: 2005-03-01
Classification: G01J

Abstract:
1. A broad-band illuminator for illuminating a sample in an optical metrology apparatus comprising: a first light source emitting radiation over a first broadband emission spectrum; a second light source emitting radiation over a second broadband emission spectrum, said second light source being substantially transparent over a portion of the first broadband emission spectrum; a first optical system for directing a portion of the radiation emitted from the first light source through the second light source and for focusing the radiation from the first light source to produce a first image of the first light source at a first focal position substantially coincident with the second light source; a second optical system for focusing a portion of the radiation emitted from the second light source to produce a second image of the second light source at a second focal position, and for relaying the first image of the first light source from the first focal position to the second focal position; an aperture placed at the second focal position; and a third optical system for focusing the radiation transmitted by the aperture onto the sample and creating an image of the aperture at the sample.