XUV/X-ray Radiation Damage to Amorphous-Carbon Optical Coatings

Amorphous carbon optical coatings are often applied to optics on the new generation of free-electron lasers working in the XUV and soft x-ray spectral regions. The response of these coatings to short-wavelength radiation applied at relatively low fluence for long periods was investigated with a focused beam of high-order harmonics. Material expansion of several nanometers was found on irradiated surfaces by atomic force microscopy (AFM). The results of these experiments were compared to those obtained for the same material with single shots from a soft x-ray Ne-like Zn laser.