Achromatic spectroscopic ellipsometer with high spatial resolution

The invention concerns an achromatic spectroscopic ellipsometer for analysing small regions of a sample (1) over a wide range of wavelengths from ultraviolet (UV) to infrared (IR). The spectroscopic ellipsometer contains a light source (2) emitting a light beam (3). The light beam (3) goes through a polarisation state generator section (4) before being focused at an incidence angle by a first parabolic mirror (5) to a small spot on sample (1). A second parabolic mirror (6) collects the reflected beam (16) and connects said beam to an analysing section (7). The reflected beam (16) emerges from the analysing section (7) to go to means (8) for detecting and analysing a spectroscopically said beam. According to the invention, the light beam (3) through the polarisation state generator section (4) up to the first parabolic mirror (5) and the light beam from the second mirror (6) through the analysing section (7) are parallel enabling achromatism. The incidence angle is largely varied without shifting of the location of the small spot on the sample surface.