Elimination of X-rays irradiated defects in fused silica by laser conditioning

Fused silica has been widely used as optical components in radiation environment. Some optical components used in these applications are frequently exposed to X-rays and other ionizing radiation, leading to the increase of optical absorption and decrease of laser-induced damage threshold, thus undermining their optical properties and operational lifetime. As on-line heating is difficult to achieve for some optical components to eliminate radiation induced defects; on the other hand off-line heating will affect the normal operation of these systems, therefore, we proposed to employ laser conditioning to eliminate radiation induced defects. The advantages of the proposed technique are demonstrated via optical absorption measurement and laser-induced damage threshold test. The experimental results show that laser conditioning can effectively reduce spectral absorption in the range from 200 nm to 320 nm in the X-rays irradiated areas and recover laser-induced damage threshold, regardless of X-rays irradiation time, 1 h or 5 h. It appears that the laser conditioning technology is potentially a useful tool to eliminate X-rays induced defects, and suited for on-line treatment in high-power laser systems.