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提出了一种利用电加热丝作为校准源的高能激光能量计校准方法,将水流从吸收腔前端导入至加热容器,在加热后流入吸收腔。通过精确计量水流吸收的热能并与能量计测量结果进行比较,达到对高能激光能量计校准的目的。研究表明校准系统的热交换模型与吸收腔内的热交换模型一致,均经历了储能和功率平衡两个阶段。水流及相变气体的散射效应对测量结果的影响较小,经过修正后可以忽略其影响。通过深入分析各个环节的测量不确定度表明,残留能量和流量变化对测量不确定度的影响最显著,增加水箱的容积可以有效降低残留能量对测量不确定度的影响。在对各个环节的影响修正后估算出系统的测量不确定度约为4.8%(k=2),被校高能激光能量计校准后的测量结果与其他类型的参考高能激光能量计进行比对,两者具有很好的一致性,修正因子仅为1.006,标准偏差为1.4%。 相似文献
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采用量热法的高能激光能量计用于测量能量大于50 kJ的连续波高能激光能量,通常用已知功率的连续激光开展激光能量计的光电校准需要激光照射时间超过20 min,而由于热损失等原因,进行长时间激光能量校准时,校准不确定度高达12%。以量热式平面吸收高能激光能量计为模型,从理论上分析了热辐射、热对流对连续波高能激光能量测量结果的影响,得到了较准确的平面吸收腔激光能量计冷却数学模型,实现了能量计热损失补偿,并通过建立相应的实验装置验证了该模型,用其对装置的测量结果加以修正,可使光电校准的测量不确定度减小到1%以下。 相似文献
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针对宽波段、高精度、大能量范围的激光能量测量需求,设计了激光能量计。利用快速响应的热电堆作为传感器,在热电堆探测面涂覆高吸收率碳纳米烯材料,实现了宽光谱吸收。采用大小2个热电堆探测器布置于能量计正反两面的方法,使能量计具有1 mJ~40 J超宽能量范围,并且具有较高的测量精度。利用有限元仿真软件建立了吸收腔热路结构的三维有限元模型,并对不同类型的激光脉冲做了加热模型模拟仿真。根据仿真结果,对探测器的线性进行了修正,从而减小了由于传感器的输出电信号与被测光信号之间的非线性所导致的测量误差。用激光能量计标准装置对能量计进行了标定实验,测量结果表明,经修正后激光能量计的测量重复性优于0.6%,线性度优于1.1%。将激光能量计溯源到国家激光能量基准,测量相对扩展不确定度达到2.5%(k=2)的优异水平。 相似文献
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In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena such as phase transitions. The unit difference method is adopted to deduce the phase transition model for water flow irradiated by a high-energy laser. In addition, the model is simulated and verified through experiments. Among them, the experimental verification uses the photographic method, shooting the distribution and the form of the air mass of water flow in different operating conditions, which are compared with the simulation results. The research shows that it is achievable to reduce the intensity of the phase transition by increasing the water flow, reducing the power intensity of the beam, shortening the distance the beam covers, reducing the initial water temperature or adopting a shorter wavelength laser. The study's results will provide the reference for the design of a water-direct-absorption-type high-energy laser energy meter as well as an analysis of the interaction processes of other similar high-power lasers and water flow. 相似文献
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现场用激光能量计校准方法的实验研究 总被引:1,自引:1,他引:0
在激光功率能量测量当中,军用激光现场检测环境温度和实验室环境温度相差很大,而激光能量计的传感器灵敏度与环境温度条件有关,不对激光能量计进行温度灵敏度校准,将严重影响测量结果。针对目前存在的问题,本文提出将激光能量计放置于温控制箱中,脉冲激光器输出的激光经过分光镜分束后分为2束激光,其中透射光由标准能量计或现场激光能量计接收,反射光由参考能量计接收,在-50℃~70℃的温度范围内进行校准的一种新方法,并进行原理性的验证实验及结果分析,得到了能量计灵敏度系数关于环境温度的函数关系,使得能量计在非标准环境下进行准确测量成为可能。为激光能量计现场测试校准技术的研究提供了一种可靠的新途径。 相似文献
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P.G. Cardinal P.L. Wizinowich R.M. Measures 《Journal of Quantitative Spectroscopy & Radiative Transfer》1981,25(6):537-545
Laser energy absorption measurements have been undertaken in an experiment involving the transmission of a pulse of laser radiation through sodium vapour. The wavelength of the laser was tuned to overlap the 589 nm resonance transition of the sodium atoms. Although simple radiation transport appears to account for the attenuation of the laser beam at low values of incident laser irradiance, anomalously large absorption has been observed at high values of incident laser energy. We suggest that this anomalous absorption of laser energy can be regarded as evidence of superlastic electron heating and subsequent ionization. 相似文献
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为解决高功率微波源传输线内能量的测量,研制了一种全吸收式液体高功率微波能量计。能量计采用乙醇、去离子水等混合液作为吸收液,吸收液吸收微波后体积膨胀,探测器内的液面升高,通过控制系统得到液面升高引起的电压变化值,从而得到被测能量的大小。该套能量计具有结构简单、测量准确度高等特点,经过实验,测得能量计端口的电压反射系数小于-20 dB,具有较好的匹配性,能够开展10~600 J能量的测量,5次测量结果标准偏差优于3%,可满足高功率微波源传输线内或空间辐射能量的测量。 相似文献
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The automation of CO2 laser output power measurement is discussed in this paper as a function of the absorber gas pressure in a cell located inside or outside the laser cavity. A manually tunable laser was used which can be operated in one of about 44 different laser lines aligned by the user and registered respectively by the acquisition program for further analysis.The voltages representing the absorber gas pressure and the output power were very small (a few hundred μV), therefore a proper voltage amplification circuit was designed to amplify the analog outputs of both the pressure meter and the laser output power meter. These amplified signals were then applied directly to a PCI-9112 ADLINK data acquisition card using a personal computer (PC).A suitable controlling program using LabVIEW graphical programming language was written to measure the pressure and laser power signals, draw the relationship between them and save the results for later processing and analysis; such as, gas absorbance coefficient α, mean absorption cross section σ calculations that can be applied in many areas such as molecular spectroscopy and environmental pollution studies. 相似文献
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现有的激光能量计传感器灵敏度系数都与其所处环境温度有关,在-50℃~70℃的温度范围内,灵敏度偏差较大,直接影响测量结果。为了达到消除环境温度的影响,采取在不同环境温度下对热释型能量计的灵敏度进行校准的研究方法。该校准方法与普通激光能量计的校准方法的不同之处在于对热释电型能量计进行校准时,温度由室温扩展到-50℃~70℃的温度范围。利用环境试验箱,每隔10℃固定一个温度点,进行激光能量的测量实验,得到各个温度点所对应的灵敏度修正系数,再借助最小二乘法建立起各个温度点上能量计灵敏度系数同环境温度的函数关系,从而实现了-50℃~70℃的温度范围内激光能量的准确计量。研制能直接工作于非常规工作环境下的热释电型激光能量计,对解决激光能量测量的外场需求有一定现实意义。 相似文献
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针对激光微能量测量的问题,提出一种激光微能量计标定新方法与装置。研究内容包括使用稳功率连续激光作为光源,通过基于斩波的脉冲发生器组件产生微能量的脉冲激光,分别使用脉冲宽度测量组件与功率测量组件进行采集、软件分析,计算微能量值及通过比对给出待标定能量计的修正系数,计算机自动控制。结果表明,该方法获得的脉冲激光波形稳定,脉冲宽度测量不确定度为0.08%,激光功率测量不确定度为0.25%,实现了对0.1 pJ~1 mJ的激光能量进行准确复现和传递。 相似文献
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The energy absorption efficiency of high-intensity (~10^{16}W/cm^2) femtosecond laser pulses in a dense jet of large rare-gas clusters has been measured. Experimental results show that the energy absorption efficiency is strongly dependent on the cluster size and can be higher than 90%. The measurement of the ion energy indicates that the average ion energies of argon and xenon can be as high as 90 and 100keV, respectively. The dependence of the average energy of the ions on the cluster size is also measured. At comparatively low gas backing pressure, the average ion energies of argon and xenon increase with increasing gas backing pressure. The average ion energy of argon becomes saturated gradually with further increase of the gas backing pressure. For xenon, the average ion energy drops a little after the gas backing pressure exceeds 9 bar (3.2×10^5 atoms/cluster). The result showing the existence of a maximum average ion energy has been interpreted within the framework of the microplasma sphere model. 相似文献
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Guo Yong Zhang Peng Xiang Zhang Hai Rong Zheng Xiang Yu Zhang Dang Li Gao Hui Zhang Li Pi Wing Kee Lee 《Optics & Laser Technology》2008,40(6):844-849
We have posed the design of a time-integral type laser energy meter based on anisotropic Seebeck effect for the first time. Anisotropic Seebeck effect is responsible for the laser-induced thermoelectric voltage effect in high temperature superconductor (HTSC) cuprates and colossal magnetoresistance (CMR) manganites thin films grown on tilted single crystal substrates. In this study, for an example, an epitaxial La2/3Ca1/3MnO3 thin film prepared on a tilted LaAlO3 substrate by standard pulsed-laser deposition (PLD) method is tested with a 1064-nm Q-switched Nd:YAG laser and its 2nd (532 nm), 3rd (355 nm), and 4th (266 nm) harmonics from room temperature to 16 K. The integral of the voltage signal with time shows a good linear relation with the laser energy per pulse in the measured wavelength and temperature range, which confirms the theoretical analysis given in this letter and can be used to design a time-integral type laser energy meter. The sensitivity increases as the film thickness increases or as the thermal diffusion constant decreases, which makes the time-integral type laser energy meter low cost as compared with the peak-voltage type. It operates with fast (nanosecond range) and broad-spectrum (from infrared to ultraviolet) response in wide temperature range (from room temperature to 10s K), and can be useful replacements for pyroelectric power/energy meters. 相似文献
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A laser power meter based on water as an absorbing medium has been developed to measure multi-kilowatt CO2 laser power with high sensitivity and accuracy. Water absorbs CO2 laser radiation readily within a very thin layer. Though water has large thermal capacity, due to short absorption length, it could vapourize at high laser powers. In order to circumvent this problem, this power meter has a centre cone and a rapidly spinning water film as the calorimetric medium. The unique feature in this development is the centre cone, which diverges the beam and reduces the power density thus reduces the possibility of vapourization. This minimizes the error in measurements. Due to the rapidly moving fluid film, it exhibits fast response at low as well as high power levels. 相似文献
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Laser materials processing is highly affected by the existence of surface plasma. The absorption of surface plasma during drilling alters the power intensity distribution of the incident laser beam across the irradiated spot. The present study is carried out to measure the electron number density and temperature using a Langmuir probe while a mathematical formulation is conducted for the absorption coefficients due to electron-ion, electron-neutral atom collisions, inverse Bremsstrahlung, and photoionization processes. Consequently, a computer program is developed to compute the relevant absorption coefficients as well as the overall absorption coefficient. The laser power intensity distribution before and after the plasma absorption is computed at a plane 2.6 mm above the workpiece surface. It is found that 13% of the reduction occurs in the incident laser output power intensity at this plane in the plasma. 相似文献
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P. -X. Zhang C. Wang G. Y. Zhang L. Yu W. K. Lee H. -U. Habermeier 《Optics & Laser Technology》2004,36(4):341-343
A prototype laser energy/power meter was designed based on the anisotropic Seebeck effect of LaCaMnO3 thin film grown on vicinal cut LaAlO3 substrate. The optical response of this device to the pulsed laser and the chopped CW laser was measured from infrared to ultraviolet. The peak voltage of the measured signal shows a good linear relation to the laser energy and power in the measured range. It was shown that at 1064 nm wavelength, this prototype device demonstrates higher sensitivity than that of commercial device. 相似文献
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高能激光能量计校准方法研究 总被引:4,自引:3,他引:1
给出了一种绝对式高能激光能量计光电校准方法.该方法以大功率灯作为校准光源,通过测量灯两端的电压以及电流获得电能值,去掉灯所消耗的热能,得到灯所发出的光能.所设计平板能量计将大功率灯密封在高能激光能量计内,光能全部被能量计吸收.根据能量计输出值以及光能值便可实现能量计光电校准.结果表明,能量计光电校准不确定度约为1.5%. 相似文献