We describe a high performance infrared spectroscopic ellipsometer IRSE working with a germanium Brewster angle reflection polarizer and a grid analyzer. This particular set-up significantly simplifies the calibration procedures since the only parameter to calibrate is the attenuation ratio of the grid analyzer. Then, the remaining errors are due to the non-linearity of the detector which can be taken into consideration in some cases. After correction, the ultimate accuracy reaches a few x 10(-3) over the entire spectral range (600 cm(-1)-7000 cm(-1)). A few examples of applications will be given; particularly on conductive materials for which IR ellipsometry can give simultaneously the thickness and the optical and electrical properties of the layers.