Characterizing lasers for cosmic ray ``test beams" at the Pierre Auger Observatory

The Pierre Auger Observatory located in western Argentina is studying extended air-shower produced by high energy cosmic rays using two detectors: a Fluorescence Detector and a Surface Detector. Because cosmic rays test beams are unavailable, laser test beams are used to measure properties of Fluorescence Detector. Optical signatures of extended air-shower and laser test beams have several similarities. This talk will discuss characterization of the laser test beams including polarization and their absolute photometric calibration.