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原子分子真空紫外光吸收和光电离绝对截面的精确测量 总被引:1,自引:0,他引:1
介绍了一种精确测量原子分子真空紫外光吸收和光电离绝对截面的实验方法。该方法的主要特点是使用圆筒形多级电极,有效地收集光电离产生的电子和离子,并利用高通量的同步辐射作光源,精确地测量分子(原子)的绝对光吸收、光电离和光离解截面,以及光电离量子产率和光学振子强度分布等。利用该方法获得了Xe原子和N2分子的一些实验结果。 相似文献
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在工业CT系统设计过程中,射线能量选择、探测器结构设计、射线源和探测器匹配等方面都涉及探测器灵敏度问题。研究了影响工业CT光电二极管探测器灵敏度的几个主要因素及其定量关系。首先分析了灵敏度的几个主要影响因素:能量沉积率、绝对闪烁效率、光收集效率、光电转换效率。然后采用蒙特卡罗方法仿真得到闪烁体的能量沉积率、光收集效率,计算了CsI(Tl)闪烁体的荧光转换效率及光电二极管的光电转换效率,定义了闪烁体与光电二极管的匹配度的概念。最后得出具有普遍意义的探测器灵敏度的表达式,理论计算值与实际测量结果最大相差20.4%,实验验证了该灵敏度计算方法的有效性和正确性。 相似文献
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提出了一种基于交替起振的光电振荡器的大量程、高精度绝对距离测量方法.此方法构建了两个光电振荡环路,分别为测量环和参考环.通过切换光开关实现测量/参考光电振荡器的交替起振;通过切换微波开关实现光电振荡器高阶/低阶振荡模式的转换;通过频率计依次记录测量/参考光电振荡器的高阶/低阶振荡频率,然后计算测量/参考光电振荡器的腔长进一步得到绝对距离.本方案的优点是:由于采用了测量/参考两个光电振荡器腔长相减的方法消除系统自身的漂移,不需要控制腔长,结构简单.实验中,利用公里量级的光纤来模拟大量程的待测距离,利用高步进精度的光延时线来模拟距离变化.在等效6 km的空间往返待测距离上,测量误差为3.5μm,相对测量精度达到5.8×10~(–10). 相似文献
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详细介绍了所制的多电极真空紫外光电离室实验装置。它主要由光学聚焦系统、真空系统、多级光电离吸收室和数据采集系统四部分组成。其主要特点是使用圆筒形多级电极收集光电离产生的电子和离子,并能精确地测量分子的绝对光吸收、光电离和光离解截面,以及光电离量子产率和光学振子强度分布等。结合光电离质谱技术,可获得碎片离子的部分光电离截面。最后给出初步实验结果。 相似文献
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综述了托卡马克装置几套常规被动光谱诊断的绝对标定方法以及利用基于碰撞辐射模型的原子数据库诊断出粒子密度以及通量等物理量的方法。其中诊断系统包括可见波段具有高时空分辨的光电二极管阵列、具有高时间分辨的光电倍增管,具有二维空间分辨的高速相机,具有时空分辨和高谱分辨的光谱仪;极紫外波段具有时空分辨的光谱仪等。 相似文献
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《光学学报》2015,(6)
从理论和实验上介绍了一种基于相关光子的多模式空间纠缠特性新型定标方法,实现了光电倍增管的量子效率绝对定标。该方法利用355 nm连续紫外激光器抽运BBO非线性晶体,不仅制备了一对710 nm/710 nm的简并相关光子和一对700 nm/720 nm的非简并相关光子,并且定标了光电倍增管的量子效率。同时介绍了实验原理和定标装置,并且对定标结果进行了不确定度分析。结果表明,利用相关光子的多模式相关性光辐射定标方法的相对合成不确定度小于4.7%。基于相关光子多模式空间相关性获得光电倍增管的量子效率,修正后并与出厂检测结果进行了比对,信号光通道的相对差异分别为10.3%、10.2%,空闲光通道的相对差异分别为12.9%、8.95%。初步验证不依赖时间符合测量的方法,只需对两路的光子计数进行统计,即可实现探测器量子效率的绝对定标。 相似文献
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Novel phase-coding method for absolute phase retrieval 总被引:2,自引:0,他引:2
This Letter presents a novel absolute phase recovery technique with phase coding. Unlike the conventional gray-coding method, the codeword is embedded into the phase and then used to determine the fringe order for absolute phase retrieval. This technique is robust because it uses phase instead of intensity to determine codewords, and it could achieve a faster measurement speed, since three additional images can represent more than 8(2(3)) unique codewords for phase unwrapping. Experimental results will be presented to verify the performance of the proposed technique. 相似文献
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J. Zhang Z. H. Lu Y. H. Wang T. Liu A. Stejskal Y. N. Zhao R. Dumke Q. H. Gong L. J. Wang 《Laser Physics》2007,17(7):1025-1028
We demonstrate a method to determine the absolute mode number of a frequency comb when it is used for high-precision laser frequency measurement, without the help of wavemeters. Our technique involves changing the repetition rate of the frequency comb in a two-step process. Guidelines for choosing the correct repetition rates for different laser linewidths are given. As a demonstration, the absolute frequencies of two lasers with different linewidths are measured with our method. 相似文献
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以环己酮为溶剂 ,无水乙醇为沉淀剂 ,溶解 -沉淀法消除增塑剂的干扰 ,以锗晶体为反射晶体 ,衰减全反射红外光谱法定性测定聚氯乙烯成分。该法简单、快速、安全、准确。 相似文献
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In this paper, the principle of linear frequency-modulation (LFM) with an external microcavity laser is analyzed mathematically and a method to establish the math model of LFM heterodyne interference is presented. The expression of LFM heterodyne interference is deduced by an illustration of a triangular frequency modulation. At present, one application of the LFM technique is non-guide absolute distance measurement. Experimental results of a system for absolute distance measurement based on a microchip solid laser and LFM technique are given. Based on the precisely theoretical model some effective approaches to improve the performance of LFM and decrease the measuring error are discussed. 相似文献
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CHEN Yan ZHAO Yang 《Chinese Journal of Lasers》2000,9(3):219-225
1 Introduction Thetechniqueoflinearfrequencymodulation(LFM)interferometrybasedonfrequencytunningcharacteristicsofasemiconductorlaser,hasbeenwidelyinvestigatedinthefieldofmeasuringabsolutedistanceandsurfaceprofile[1].ALDpumpedmicrochipsolidlaserdeveloped… 相似文献
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A new method of absolute phase evaluation for three-dimensional (3D) profile measurement using fringe projection is presented, which combines the gray code and the phase shift technique. Two kinds of fringe patterns are projected onto the object surface respectively, one is sinusoidal intensity distribution used for phase demodulation and the other is gray code fringe pattern for unwrapping. These images are acquired by camera and stored into computer. The absolute phase is obtained by analyzing these images. The validity of this method is verified experimentally. The method is superior to other phase unwrapping methods. 相似文献
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C. Forno 《Optics & Laser Technology》1975,7(5):217-221
This describes a new optical technique for displaying both small surface displacements and the absolute shape of large objects. The method is based on recording fine detail appearing in random patterns applied to the surface. The detail is recorded at a high spatial frequency using a modified 35 mm camera and fine grain film. Information concerning relative and absolute displacements is contained in light diffracted by the processed negative. 相似文献
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We present a method of measuring the absolute phase in heterodyne-detected transient grating experiments. The method permits direct and sensitive characterization of the amplitude and phase of the grating parameters. We also present a convenient implementation of this technique and demonstrate its efficacy in a cuprate superconductor. 相似文献
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L. A. Blagonravov O. O. Karchevskii P. V. Ivannikov A. V. Soboleva 《Moscow University Physics Bulletin》2008,63(1):49-54
An extension of a recently proposed compensation technique [1, 2] is elaborated to measure the thermal expansion coefficient of conducting fluids. The method is based on simultaneously exerting two modulation effects of different physical natures on a studied sample. This technique enables direct local measurements of the thermal expansion coefficient expressed in absolute units. 相似文献