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A new geometrical method to determine the surface damage threshold for ultrashort pulses is presented. It consists in the formation of a surface damage profile by a movement of the sample across the laser beam focus. A single measurement of the maximum transversal dimension of this damage profile, which depends solely on the laser beam power, is used to calculate the local damage threshold intensity. It is also theoretically shown that the damage in the transverse dimension can be controlled under the diffraction-limited spot. 相似文献
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In order to increase the damage threshold of metal mirrors we propose to create a special structure on the surface of the mirrors (“photonic surface”). This structure must have the period about λ/2 and will suppress propagation of surface plasmons with the frequency ω0=2πc/λ along the surface. This structure will also slightly increase the heat removal from the mirror’s surface by the excitation of the thermostimulated plasmon emission from the surface. The heat removal from the surface is estimated and possible implementation of this approach for use with CO2-lasers (λ=10.6 μm) and Nd-YAG-lasers (λ=1.06 μm) is analyzed. 相似文献
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为了提高熔石英元件表面抗激光损伤阈值,利用超声波辅助HF酸研究平滑光学元件表面缺陷形貌和去除刻蚀后残留物效果,通过扫描电子显微镜电镜和原子力显微镜记录表面形貌结构,以及单脉冲激光辐照测试抗损伤阈值确定实验参数。研究表明,超声波场的引入能催化HF酸的刻蚀速率、提高钝化效果并且更易剥离嵌入的亚μm级杂质粒子。经过实验测试,获得了熔石英类元件相匹配的超声辅助HF酸刻蚀实验参数,研究结果对应用超声波辅助HF酸研究熔石英表面抗激光损伤有重要意义。 相似文献
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The laser damage threshold inside fused silica is dependent not only on the numerical aperture (NA) of the focusing objective, but also on the polarization of the incident femtosecond laser pulses. The damage threshold for circularly polarized beams is higher than that for linearly polarized beams when NA>0.4, but the former was lower than the latter when NA<0.4. The reverse might be due to different damage processes: laser induced damage at high NA and the self-focusing induced breakdown at low NA. 相似文献
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用原子力显微镜和光学显微镜观测酸蚀后熔石英亚表面划痕,并根据形貌特征将其分为Boussinesq-point-force crack(BPFC)、Hertzian-conical scratch(HCS)和Plastic indent(PI)三类,测试了各类划痕的损伤阈值,讨论了激光损伤机制。结果表明锐度较大的BPFC损伤阈值不超过2.0 J/cm<>2;深度小于1 μm的 HCS阈值可达2.6 J/cm2;形变较大的PI阈值至2.8 J/cm2,形变较小的PI的激光损伤阈值与无缺陷材料相当。BPFC 和深度超过1 μm的HCS是导致熔石英损伤阈值低的主要因素。 相似文献
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用原子力显微镜和光学显微镜观测酸蚀后熔石英亚表面划痕,并根据形貌特征将其分为Boussinesq-point-force crack(BPFC)、Hertzian-conical scratch(HCS)和Plastic indent(PI)三类,测试了各类划痕的损伤阈值,讨论了激光损伤机制。结果表明锐度较大的BPFC损伤阈值不超过2.0 J/cm<>2;深度小于1 μm的 HCS阈值可达2.6 J/cm2;形变较大的PI阈值至2.8 J/cm2,形变较小的PI的激光损伤阈值与无缺陷材料相当。BPFC 和深度超过1 μm的HCS是导致熔石英损伤阈值低的主要因素。 相似文献
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To solve the problem of large error when measure the laser induced damage threshold of thin films in the case of Gaussian distribution beam induced damage thin films, optical system of flattop beam shaper which is capable of redistributing a beam with a Gaussian profile to a flattop profile was designed with optical design software ZEMAX. The Fermi-Dirac beam model was chosen as the distribution function of the flattop beam in this paper, the mapping formula of the input Gaussian beam and the output flattop beam was establish, the surface coefficient of aspheric was given. The energy conversion efficiency was 95.33% and the flattened degree was 93.66% in this design. The accuracy of measurement has been improved when measure the laser induced damage threshold of thin films by the flattop beam. 相似文献
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光学减反膜是激光系统的重要组成部分,也是在激光照射下最容易发生损伤的部分,如何提高减反膜的激光损伤阈值是研究的热点之一。在保持目标透射光谱要求和膜系总光学厚度不变的前提下,研究了不同梯度化减反膜与激光损伤阈值之间的关系。首先采用混合渐变膜系设计方法设计了一种渐变减反膜系,G/H1→H/L/A;其次通过渐变折射率分层等效方法将渐变减反膜系进行不同的梯度化,并利用PECVD技术,在K9玻璃上沉积了满足光学性能指标要求的不同渐变减反膜系(多层梯度渐变膜系和相应的坡度渐变膜系);最后进行了激光损伤阈值(LIDT)测量。研究结果表明:在保持目标透射光谱要求和膜系总光学厚度不变的前提下,渐变减反膜系相比于传统减反膜系,抗激光损伤阈值有明显的提高;随着梯度化层数的增加,渐变减反膜系的激光损伤阈值呈减小的趋势;对于相同膜层的渐变折射率薄膜,采用坡度法制备的样片抗激光损伤阈值均优于采用梯度化制备的样片。 相似文献
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采用HPM溶液(盐酸、双氧水和去离子水的混合液)结合氧等离子体对多层介质膜脉宽压缩光栅进行清洗研究。用X射线光电子能谱检测光栅表面的元素成分及其原子含量的变化。实验结果表明,氧等离子体处理能有效去除光栅表面残留光刻胶和碳氟化合物; 再经HPM溶液清洗,反应离子束刻蚀和氧等离子体处理过程产生的金属污染物被进一步去除。经过上述清洗工艺处理后,光栅一级衍射效率仍保持在95%以上,光栅表面激光诱导损伤阈值达到1.6 J/cm2 (1053 nm, 10 ps)。实验结果说明了氧等离子体和HPM溶液相结合能有效清洗多层介质膜脉宽压缩光栅,并显著提高光栅损伤阈值。 相似文献
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针对传统的激光诱导损伤阈值测试中存在的耗时问题,提出了一种利用单发次、大口径光束的介质膜损伤阈值的快速测定方法。该方法以图像处理为基础,通过坐标变换和栅格压缩,建立了样品辐照区域内损伤分布与光斑强度分布之间的精确对应关系。基于对大口径光斑辐照区域内损伤信息的快速提取和统计方法,通过单次激光辐照,获取了待测区域的损伤阈值。根据此方法搭建了单发大口径光束损伤阈值测试平台,并对HfO2/SiO2高反射膜损伤阈值进行了单发次测定的验证。 相似文献
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A.M. Chen 《Applied Surface Science》2010,257(5):1678-1683
The heating processes of the single-layer gold thin film and the two-layer film assembly of gold padded with other metal (silver, copper and nickel) irradiated by femtosecond laser pulse are studied by the two-temperature model. It is found that the substrate metal can change energy transport, which is corresponding to the temperature changing process, and the thermal equilibrium time. Compared with the single-layer gold film at the same laser fluence, the two-layer film structure can change the damage threshold of the gold surface. Our results indicate that we can maximize the damage threshold of the gold film surface by altering the thickness ratio of the gold layer and the substrate layer in the two-layer film assembly. 相似文献
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Study of organic silicon resin protective coating with high laser damage threshold for KDP crystal 总被引:1,自引:0,他引:1
StudyoforganicsiliconresinprotectivecoatingwithhighlaserdamagethresholdforKDPcrystalTANGYongxing;ZHANGWeiqing;ZHOUWeiping;ZHU... 相似文献
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