LBO晶体上具有不同厚度过渡层的倍频增透膜的设计和制备

Design and preparation of frequency doubling antireflection coating with different thicknesses of interlayer were investigated for LiB₃O₅ (LBO) substrate. The design was based on the vector method. The thickness of the inserted SiO₂ interlayer could be changed in a wide range for the four-layer design with two zeros at 1064 and 532 nm. The coatings without any interlayer and with 0.1 quarter-wave (λ/4), 0.3 λ/4, 0.5 λ/4 SiO₂ interlayer were deposited respectively on LBO by using electron beam evaporation technique. All the prepared coatings with SiO₂ interlayer indicated satisfying optical behavior. This expanded our option for the thickness of an interlayer when coating on LBO substrate. The prepared films with SiO₂ interlayer showed better adhesion than that without any interlayer. The thickness of the interlayer affected the adhesion, the adhesion for the coating with 0.5 λ/4 SiO₂ interlayer was not as good as the other two.}

LBO晶体上1064，532nm倍频增透膜的镀制及性能分析

用电子束蒸发沉积方法在X切LBO（X-LBO）晶体上镀制了两种不同膜系结构的1064和532nm倍频增透膜，其中一种膜系结构为基底／ZrO2／Y2O3／A12O3／SiO2／空气，另一种为基底／0．5Al2O3／ZrO2／Y2O3／A12O3／SiO2／空气，两种膜系结构的主要差别在于有无氧化铝过渡层。测量了薄膜的反射率光谱曲线，发现两种增透膜在1064和532nm处的反射率均小于0．5％，实际镀制结果与理论设计曲线的差异主要是由材料折射率的变化引起的。且对样品在空气环境中进行了温度为473K的退火处理，

沉积温度对LaF3薄膜性能的影响

abstract {LaF₃ single-layer coatings were prepared by thermal boat evaporation at the deposition temperatures of 189, 255, 277 and 321°C respectively. The crystal structures of the coatings were characterized by X-ray diffraction (XRD). A spectrophotometer was employed to measure its transmittance. Moreover, refractive index, extinction coefficient and cut-off wavelength were obtained from the measured transmittance spectral curve. The residual stress was evaluated by the Stoney's equation and optical interferometer. Laser induce damage threshold (LIDT) was performed by a tripled Nd:YAG laser system. The results show that the crystallization status becomes better with the deposition temperature increasing. Correspondingly, the grain size also gets larger. Meanwhile, the coatings become more compact and the refractive index increases. However, the absorption of coatings seriously rises and the cut-off wavelength drifts to the long wave. In addition, the residual stress also increases and the intrinsic stress plays a determinant role in the coating. The LIDT of the coating also enhances at high temperature.}

渐变折射率薄膜的分层评价探讨

首先阐述了将渐变折射率薄膜细分为多层均匀薄膜的分层介质理论，接着给出了一种获得最佳分层数目的分层评价方法，最后以线性变化渐变折射率薄膜为例说明了如何优化获得渐变折射率薄膜的分层数目．研究发现：渐变折射率薄膜的分层数目与薄膜的厚度和薄膜的折射率变化快慢有关，在一定的折射率变化范围内，渐变折射率薄膜的分层数目随着薄膜厚度的增加先减小后增大．

真空室内金属杂质污染对光学薄膜性能的影响

真空室内金属粒子污染是降低激光薄膜性能的一个重要因素。采用高真空残余气体分析仪,对薄膜沉积过程中的气氛进行分析。发现由黄铜制作的加热灯架在工作时会分解出Zn,在这种条件下沉积薄膜,会使薄膜中掺入金属杂质,导致薄膜激光破坏阈值降低。采用表面分析技术对薄膜的组分进行分析,证实薄膜中锌杂质的存在。激光破坏实验证明,含有锌杂质的薄膜的破坏阈值明显降低。

沉积速率对热舟蒸发LaF3薄膜性能的影响

用热舟蒸发方法在不同的沉积速率下制备了LaF3单层膜,并对部分单层膜进行了真空退火。分别采用X射线衍射(XRD),Lambda 900 光谱仪和355 nm Nd∶YAG脉冲激光测试了薄膜的晶体结构、透射光谱和激光损伤阈值(LIDT),并通过透射光谱计算得到样品的折射率和消光系数。实验结果表明,增大沉积速率有利于LaF3薄膜的结晶和择优生长,可以提高薄膜的致密性和折射率,但薄膜的抗激光损伤能力有所下降;沉积速率太大,又会恶化薄膜的结晶性能,同时薄膜中产生大量孔洞,薄膜的机械强度降低,导致薄膜的折射率减小和

Nd：YAG激光器光栅式扫描预处理的计算模拟与优化分析

采用计算模拟的方法．研究了光栅式扫描预处理的扫描方式以及脉冲能量波动、定位误差对预处理效率的影响。研究发现。脉冲能量波动及其定位误差使预处理效率降低，同时其影响与扫描方式之间存在相互调制作用．因此可以通过选择合适的扫描方式以及扫描间隔来优化预处理流程，提高预处理效率。此外发现，光斑呈等边三角形排列时的预处理效率优于正方形。

低损耗193nm增透膜

计算了适用于193nm增透膜设计与制备的基底与薄膜材料的光学常数,并在此基础上对193nm增透膜进行了设计、制备与性能分析.发现基底材料的吸收损耗对增透膜元件的影响很大,超过一定值时,增透膜元件的设计透过率将达不到理想水平.对单面增透膜的设计与制备结果表明,当吸收损耗降低到一定程度,散射损耗成为不可忽略的因素.采用热舟蒸发方法实现了性能良好的193nm减反射膜,剩余反射率在0.2%以下.

4H-SiC基底Al_2O_3/SiO_2双层减反射膜的设计和制备

在4H-SiC基底上设计并制备了Al2O3/SiO2紫外双层减反射膜,通过扫描电镜(SEM)和实测反射率谱来验证理论设计的正确性。利用编程计算得到Al2O3和SiO2的最优物理膜厚分别为42.0nm和96.1nm以及参考波长λ=280nm处最小反射率为0.09%。由误差分析可知,实际镀膜时保持双层膜厚度之和与理论值一致有利于降低膜系反射率。实验中应当准确控制SiO2折射率并使Al2O3折射率接近1.715。用电子束蒸发法在4H-SiC基底上淀积Al2O3/SiO2双层膜,厚度分别为42nm和96nm。SEM截面图表明淀积的薄膜和基底间具有较强的附着力。实测反射率极小值为0.33%,对应λ=276nm,与理论结果吻合较好。与传统SiO2单层膜相比,Al2O3/SiO2双层膜具有反射率小,波长选择性好等优点,从而论证了其在4H-SiC基紫外光电器件减反射膜上具有较好的应用前景。

高反射率193nm反射膜的实现

对应用于193nm反射膜的基底材料、薄膜材料、沉积技术与主要沉积工艺参数进行了分析与优化选择，在此基础上进行了193nm反射膜的设计、制备及后处理，实现了时间稳定性与环境稳定性良好的193nm反射膜，反射率达98％以上。

电子束蒸发镀膜速率控制

介绍了电子束蒸发镀膜速率控制的基本原理和方法,选取实际生产中大量使用且蒸发特性较难控制的SiO_2和HfO_2,对两者的电子束蒸发速率控制分别进行了实验研究。采用比例积分微分(PID)闭环反馈控制,通过Ziegler-Nichols工程经验公式进行原始参量整定,并在实验的基础上对控制器的原始参量进行调整以及对积分作用和微分作用进行分区处理,速率控制的实验结果表明,采用该参量整定方法并结合工艺流程的改进,能获得良好的速率控制。针对速率控制中存在的难点问题进行了分析,并提出改进措施:将速率控制和电子枪扫描控制相结合能进一步改善速率控制。

真空紫外光学薄膜及薄膜材料

概述了真空紫外(VUV)波段光学薄膜及薄膜材料的研究进展,金属Al膜因到短至80nm还能提供较高的反射率而得到普遍关注,在高真空和30nm/s左右沉积速率下沉积了保护层的金属Al膜在157nm处反射率可达90%。介质氧化物薄膜机械应力小,环境稳定性比氟化物薄膜好,在190nm以上波段应用较广泛,但在180nm以下波段吸收大大增加而应由氟化物薄膜取代。氟化物薄膜带宽大、吸收系数小,沉积了致密SiO2保护层的氟化物高反膜,在中心波长180nm处可得到接近99%的反射率,而且膜系的稳定性和抗激光损伤也大大提高。氟化物减反膜在157nm处可得到0.1%以下的反射率;到目前为止氟化物薄膜最好的沉积工艺是电阻热蒸发。

Techniques for fabrication of large-size graded reflectivity mirrors

According to the parameter requirements of a graded reflectivity mirror with a Gaussian profile, the layer structure and the mask pattern are designed using a graded-thickness middle layer. The mask and the automatic mask-switchover equipment are designed considering the actual requirement of the thin films and the specific deposit facility. The uniformity of the layer thickness is analyzed. The measurement results indicate that samples prepared with this technique are basically in accordance with the design parameter. The scattering effect between the material molecules and the mask, thickness errors, and the alignment error between the mask and the substrate are the main factors that influence the deposit result. (c) 2008 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3027595]

Working pressure dependence of properties of Al2O3 thin films prepared by electron beam evaporation

The effects of working pressure on properties of Al2O3 thin films are investigated. Transmittance of the Al2O3 thin film is measured by a Lambda 900 spectrometer. Laser-induced damage threshold (LIDT) is measured by a Nd:YAG laser at 355nm with a pulse width of 7ns. Microdefects were observed under a Nomarski microscope. The samples are characterized by optical properties and defect, as well as LIDT under the 355 nm Nd: YAG laser radiation. It is found that the working pressure has fundamental effect on the LIDT. It is the absorption rather than the microdefect that plays an important role on the LID T of Al2O3 thin film.

引入过渡层提高介质减反膜的抗激光损伤阈值

提出了一种用于提高介质减反膜的损伤阈值的新的方法，在H2.5L (H:HfO2, L:SiO2)的膜层与基底之间引入4个1/4光学厚度的SiO2薄膜，发现抗激光损伤阈值提高了50%，并且保持1064nm处的反射率低于0.09%。本文分析了造成这一提高的机制，一定厚度的氧化硅过渡层的引入是一种提高介质减反膜的损伤阈值的灵活有效的方法。