Patent ID: 7508510

Claim:
A method of analyzing substantially the exact same spot of a sample with multiple wavelengths of electromagnetic radiation, comprises 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 a lens system, comprising two lenses, which lens system has been designed to allow change of position of said lenses with respect to a sample, and which lenses optionally provide focal lengths which are substantially exactly the same at at least two specified wavelengths; c) placing one lens of said lens system provided in step b prior to a sample which is positioned on said stage for supporting a sample, and another thereof after said sample; d) causing polychromatic electromagnetic radiation from said source thereof to become focused onto said sample by said lens positioned before said sample, and obtaining data at at least one wavelength at which said electromagnetic radiation is focused onto said sample at a point thereupon; e) moving the lenses along the locus of the electromagnetic radiation to place them at different distances from said sample and again causing said polychromatic electromagnetic radiation from said source thereof to become focused onto said sample by said lens positioned before said sample, and obtaining data at at least one wavelength at which the focal length is such that the polychromatic electromagnetic radiation is focused onto said sample at substantially exactly the same point thereupon as in step d; f) utilizing only data obtained which correspond to said substantially same point on said sample in sample analysis.