Patent ID: 7345762

Claim:
A method of analyzing a sample at the exact same spot with at least two wavelengths of electromagnetic radiation, comprising the steps of: practicing steps a and b in either order, said steps a and b being: a) providing a selection from the group consisting of: ellipsometer; polarimeter; spectrophotometer; and reflectometer; which sequentially comprises a source of polychromatic electromagnetic radiation, a stage for supporting a sample and a detector; b) providing at least one lens and placing said at least one lens prior to a sample which is positioned on said stage for supporting said sample; c) causing electromagnetic radiation of a first wavelength from said source thereof to become focused onto said sample at a spot thereupon of a desired spot size by said pre-sample lens, such that after interaction with said sample said electromagnetic radiation enters a detector; d) causing electromagnetic radiation of a second wavelength from said source thereof to become focused onto said sample by said pre-sample lens at the same spot, said lens being moved toward or away from said sample such that the said electromagnetic radiation of said second wavelength forms a spot size the same as that in step c, such that such that after interaction with said sample said electromagnetic radiation enters a detector; e) analyzing said sample utilizing only data provided by said detector based upon said first and second wavelengths.