Verwendung eines spektroskopischen Ellipsometers

The present invention provides a spectroscopic ellipsometer capable of measuring an infinitesimal area with a high degree of precision. The present invention provides a spectroscopic ellipsometer comprising an irradiating optical system for irradiating the surface of a sample with polarized light, and a detective optical system for outputting data with respect to the surface of the sample based on an amount of polarization state change of elliptically polarized light reflected on the surface of the sample, wherein an F-number fS/DS of the above-mentioned irradiating optical system is set to a level being suitable for obtaining a beam spot diameter at the surface of the sample, and an F-number fK/DK of the detective optical system is set to be higher than the F-number fS/DS of the irradiating optical system, wherein fS and fK are respective focal lengths of the irradiating/detective optical systems, and DS and DK are respective diameters of light beams passing through the irradiating/detective optical systems.