Disclosed is an achromatic spectroscopic ellispometer for analyzing small regions of a sample over a wide range of wavelengths from ultraviolet (UV) to infrared (IR). The spectroscopic ellipsometer contains a light source emitting a light beam which passes through a polarisation state generator section before being focused at an incidence angle q by a first parabolic mirror to a small spot on a sample. A second parabolic mirror collects the reflected beam and connects said beam to an analyzing section. The reflected beam emerges from the analyzing section and is spectroscopically detected and analyzed. The light beam through the polarisation state generator section up to the first parabolic mirror and the light beam from the second mirror through the analyzing section are parallel enabling achromatism. The incidence angle q is largely varied without shifting of the location of the small spot on the sample surface.