THz performance of the infrared beamline at BESSY

Spectroscopy with electromagnetic radiation in the frequency range from hundreds of GHz to few THz has attracted considerable interest in the last decade. Scientific cases and applications are abundant. Synchrotron Radiation facilities can play an important role in the next years to develop prototypes of THz instruments and detectors and to perform scientific experiments by providing a well characterized, powerful, broadband coherent synchrotron radiation source. However, the propagation of sub-THz and THz electromagnetic waves through a typical infrared beamline to the end stations is strongly affected by diffraction. This paper presents the THz performance of the infrared beamline at the electron storage ring BESSY II. Results from wave propagation calculations will be discussed and compared to experimental findings.