355 nm增透膜的设计、制备与性能

用热舟蒸发法结合修正挡板技术制备了355 nm LaF3/MgF2增透膜,并对部分样品进行了真空退火.采用Lambda 900光谱仪测试了增透膜的低反光谱和透射光谱,并考察了其光谱稳定性;使用脉冲8 ns的355 nm激光测试了增透膜的激光损伤阈值(LIDT);采用Normarski显微镜对增透膜的表面缺陷密度和破斑形貌进行了观察.实验结果表明,制备得到的增透膜的剩余反射率较低,光谱稳定性好;真空退火对增透膜的激光损伤阈值没有改善;增透膜的破环形貌为散点形式,结合破斑深度测试表明薄膜的破坏源于薄膜和基底界面的缺陷点.JGSl熔石英基底由于有好的表面状况、固有的高激光损伤阈值和以其为基底的增透膜具有更低的表面场强,使得其上的增透膜有更高的抗激光损伤能力.

Design,Preparation and Characterization of 355 nm Antireflection Coatings

355 nm LaF3/MgF2 antireflection coatings were prepared by thermal boat evaporation combining masking technology.Some of these coatings were annealed in vacuum.The reflectance and transmittance spectra of the anti-reflective coatings were measured by a spectrophotometer Lambda 900.Meanwhile,the spectrum stability is tested.Laser induce damage threshold(LIDT) was performed by a 355 nm laser system with 8 ns pulses.The results show that the prepared anti-reflective coatings have very low reflectance and good spectrum stability.The vacuum annealing has no effect upon the LIDT.The damage morphologies are shown as dispersive spots.Moreover,the deep analysis shows that the damage origins from the defect at the film-substrate interfaces.The JGS1 substrate has better surface condition and higher laser damage resistance,and the antireflection coatings upon it has lower surface electric-field intensity.These advantages make the antireflection coatings on these substrates have higher LIDT.