P46	March 2000

¹ Institut d'Astrophysique et de Géophysique - Université de Liège, Avenue de Cointe 5, 4000 Liège, Belgium

^* Chercheur Qualifié FNRS, Belgium

Abstract

     We present here a procedure written within the ESO MIDAS reduction package with the aim of deriving semi-automatically linear polarization data from CCD images obtained with beam-splitters such as those available at the ESO 3.6m telescope equipped with EFOSC2 or at the VLT equipped with FORS1. This method is adequate for point-like objects and was used for measuring quasars polarization. We also report on the detection of a significant image deformation effect, most probably due to the recent addition to EFOSC2 of a rotatable half-wave plate.