A broadband ellipsometer/polarimeter system for analyzing a sample includes an illumination source emitting a polychromatic light beam, a polarization state generator (PSG) including a fixed linear polarizer and a substantially achromatic retarder mounted on a rotating holder, a sample holder, a polarization state analyser (PSA) including a fixed linear polarizer and a substantially achromatic retarder mounted on a rotating holder, a primary detection system measuring the intensities at each wavelength of the light beam transmitted through the PSA, optics to collimate the beam into the PSG and into the PSA and to focus the beam into the sample surface and the detector. The linear polarizer and achromatic retarder in the PSA are identical to those of the PSG but mounted in a reverse order.