PYRAMIR: construction and implementation of the world's first infrared pyramid sensor

In this paper we present an overview of the construction and implementation of the unmodulated infrared pyramid wavefront sensor PYRAMIR at the Calar Alto 3.5 m telescope. PYRAMIR is an extension of the existing visible Shack-Hartmann adaptive optics system ALFA, which allows wavefront sensing in the near-infrared wavefront regime. We describe the optical setup and the calibration procedure of the pyramid wavefront sensor. We discuss possible drawbacks of the calibration and show the results gained on Calar Alto