真空紫外波段铝反射膜制备

为制备出在130～210nm波段具有良好光谱性能的铝反射膜,优化设计了铝反射镜中铝层和保护层氟化镁的厚度,理论确定铝层和氟化镁保护层最佳厚度分别为80nm和33nm。采用热舟蒸发工艺,在BK7基片上制备了Al反射膜样品,获得了130～210nm波长范围内反射率均大于80%的金属铝膜。研究了铝层沉积速率和紫外辐照处理对薄膜性能的影响,并考察了铝膜光谱性能的时效性。结果表明铝层沉积速率越快,制备的铝膜反射率越高;合理地存放铝膜元件,可以长时间内保持铝膜的光谱性能。适当的紫外辐照处理能进一步提高铝膜在真空紫外波段的反射率。     

Determination of optical constants in DUV/VUV

An approach for determining the optical constants of the weakly absorbing substrate is developed and applied to obtain the parameters of CaF2 and fused silica substrates in deep ultraviolet （DUV） and vacuum ultraviolet （VUV） range. A method for extracting the optical constants of thin films deposited on strongly absorbing substrate, which is based on the reflectance spectra measured at different angles of incidence, is also presented. The optical constants are determined by fitting the measured spectra to the theoretical models. The proposed method is applied to determine the refractive index and extinction coefficient （n, k） of MgF2 film deposited on silicon substrate by electron beam evaporation with substrate temperature 300 ℃ and deposition rate 0.2 nm/s. The determined n, k values at 193 nm are 1.433 and 9.1×10-4, respectively.     

Refractive index inhomogeneity of LaF3 film at deep ultraviolet wavelength

It is well known that the optical property of an optical thin film can be influenced by even small inho- mogeneity of refractive index （RI）. In order to investigate the RI inhomogeneity of LaF3 single layer in deep ultraviolet （DUV） range, single-layer LaF3 samples deposited on fused silica and CaF2 substrates are prepared by resistive heating evaporation at different deposition temperatures. The reflectance and transmittance spectra of LaF3 film samples are measured with a spectrophotometer, and used to calculate the RI inhomogeneity. The experimental results show that no RI inhomogeneity of LaF3 film is observed when deposited on CaF2 substrate, while negative RI inhomogeneity is presented when deposited on fused silica substrate. The level of inhomogeneity is affected by the substrate temperature, which decreases with the increasing substrate temperature from 250 to 400 ℃.     

Anti-Reflective Fluoride Coatings for Widely Tunable Deep-Ultraviolet Diode-Pumped Solid-State Laser Applications

An anti-reflective （AR） fluoride coating in the 170-230 nm spectral range is prepared by the thermal evaporation method for the applications of widely tunable deep-ultraviolet diode-pumped solid-state lasers. The transmittance of an AR coated calcium fluoride （CaF2） window in thickness 3mm is measured to be in the range of 95.8% at 170 nm to 97.1 % at 230 nm, with the maximum transmittance 99.2% and the minimum residual reflectance 0.04% appeared at 195 nm. The experimental results indicate that treating the AR coated window and the bare substrate with ultraviolet irradiation can significantly improve their optical performance.     

光度法确定LaF3薄膜光学常数

为了满足设计和生产多层膜系时精确确定薄膜材料光学常数的需要,建立一种基于透射率光谱包络来获取弱吸收光学薄膜光学常数的均匀模型.为消除基底背面反射对光学薄膜光谱性能测量的影响,给出一种非破坏性的薄膜光学特性校正方法,校正实测光谱数据获得光学薄膜的单面光谱,并给出确定基底光学常数的方法.研究钼舟热蒸发工艺制备的沉积在CaF...