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为了测量K9玻璃的折射率,采用三次谐波法,通过调节位移平台使两束平行飞秒激光脉冲在时空上重合,进而产生强烈的三次谐波信号,并进行了理论分析和实验验证,对放入样品前后的实验数据进行处理,得到了样品K9柱面镜的折射率及其测量精度,还对两片折射率未知的衰减片进行了测量,得到了它们的折射率。结果表明,测得的样品折射率与实际折射率符合得很好,证实了该方法测量物体线性折射率的可行性;与传统测量方法相比,该方法具有操作简便、样品容易加工的优点,对样品折射率范围没有限制,具有很重要的实用价值。 相似文献
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Single-pulse and double-pulse optical emission spectroscopy (OES) analyses were carried out in air by using ultrashort laser pulses at atmospheric pressure. The aim of this work is to use spectroscopic methods to analyze the early phase of laser-induced plasma after the femtosecond laser pulse. The temporal behavior of emission spectra of air plasma has been characterized. In comparison with the single-pulse scheme, the plasma emission obtained in the double-pulse scheme presents a more intense continuum along with several additional ionic lines. As only one line is available in the single-pulse scheme, the plasma temperature measurements were performed using only the relative line-to-continuum intensity ratio method, whereas the relative line-to-line intensity ratio method and the relative line-to-continuum intensity ratio method were used simultaneously to estimate the electron temperature in the double-pulse scheme. The results reveal that the temperature values obtained by the two methods in the double-pulse scheme agree. Moreover, this shows that the relative line-to-continuum intensity ratio method is suitable for early phase of laser-induced plasma diagnostics. The electron number density was estimated using the Stark broadening method. In the early phase of laser-induced plasma, the temporal evolution of the electron number density exhibits a power law decrease with delay time. 相似文献
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研究我国食品中放射性物质分析标准现状,完善食品安全标准体系建设。以当前食品中放射性物质分析标准的内容、应用情况和制修订状况为研究对象,剖析其中存在的不足并提出建议。分析标准在时效性、适宜性等方面与实践需求存在不相适应情况,有必要完善相关分析标准建设,为风险监测评估和应急处置提供有力的技术支撑。建议形成多方参与的标准管理工作机制、加快限量标准和响应行动水平标准的制修订、完善急常兼备的检测方法标准,持续保持分析标准的适宜性和有效性。 相似文献
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