High-performance DUV optics for Free Electron Lasers

Going to shorter wavelengths beyond the deep ultraviolet involves the development of dedicated optics for Free Electron Lasers with devoted coating techniques and characterizations. High-performance DUV optics are specially developed in order to create low loss, high reflectivity dielectric mirrors with long lifetime in harsh synchrotron radiation environment. In February 2001, lasing at 189.7 nm was obtained at the European FEL project at ELETTRA, the shortest wavelength obtained so far with FEL oscillators. In July 2001, 330 mW extracted power at 250 nm was measured with optimized transmission mirrors. Coating research and development correlated to lasing performance obtained so far is reported.