CO_2激光和等离子体清洗提高石英基片损伤阈值

Effects of CO_2 laser and vacuum plasma cleanings on silica-oil-and-grease polluted quartz substrates

采用连续CO2激光和真空等离子体相结合的方法对石英基片进行清洗。通过光学显微图、水接触角、透过率和损伤阈值测量分别表征了CO2激光和等离子体对真空硅脂蒸发物污染过的石英基片的清洗效果。研究表明:对于真空硅脂蒸发物污染后的石英基片,可以先采用低能量的CO2激光进行大面积清洗,再用真空等离子体进行精细清洗。光学显微图像表明:清洗后的基片表面的油珠被清除干净;水滴接触角由63°下降到4°;在400 nm附近,基片透过率由92.3%上升到93.3%;损伤阈值由3.77 J/cm2上升到5.09 J/cm2。

As an important window material for the target chamber, the quartz substrate＇s cleaning is vital for its laser damage threshold. In this work, the quartz substrates polluted by evaporated silica-oil-and-grease were cleaned by CO2 laser and plasma and the damage thresholds were studied. The samples were characterized via the optical microscopy photo, the water contact angle, the optical transmittance and the laser damage threshold. The experimental results showed that the substrates could be well cleaned by low energy CO2 laser combined with vacuum subsequent plasma. After cleaning, the water contact angle of the quartz substrates decreased from 63 to 4, the transmittance increased from 92.3% to 93.0%, and the damage threshold increased from 3.77 J/cm^2 to 5.09 J/cm^2 when irradiated by 351 nm, 6ns single pulse laser.