摘要
针对国内尚无功率大于300 W的激光功率计量标准的问题,提出了基于量热法的高功率激光功率量值计量方法,通过对测量参数(温差、流量、吸收腔的吸收系数等)进行量值溯源及不确定度评定,建立了基于量热法的高功率激光功率量值测量装置,实现了高功率激光功率的量值溯源传递。参考激光小功率标准装置的激光功率计量方法,对自研装置进行了计量比对验证。结果表明,自研装置的不确定度为2.8%,计量比对的归一化偏差值小于1,不确定度评估结果合理准确。
Objective Currently,most of the military laser powers reported by the public exceed 104 W level,while domestic measurement regulations exceeding 104 W level have not been released.Most laser power meters imported from abroad are used for power testing,but the measurement uncertainty is large,and strict measurement calibration and measurement value traceability cannot be conducted.Hence,to realize accurate laser power measurement,a highpower laser measurement system based on calorimetry is developed.Methods The highpower laser power measurement device designed in this study(Fig.1)(hereafter referred to as the selfdeveloped device)adopts a cylindrical cavity as the laser energy absorption cavity.The laser is incident on the reflection cone at the bottom of the cavity and diffused to the inner surface of the absorption cavity through the reflection cone to heat the absorption cavity.The laser power is determined by calculating the water flow and temperature increase.Through an uncertainty evaluation of the measurement parameters(including temperature difference,flow rate,and absorption coefficient of absorption cavity),the traceability of the highpower laser power value is realized.During the laser power measurement,it is highly important to ensure the accuracy of the temperature measurement.The main factor that affects the accuracy of temperature measurements is heat loss,which primarily includes spontaneous radiation,flow friction,and heat conduction.Stefan‒Boltzmann formula is used to calculate the radiation power of the absorption cavity,and the kinetic energy theorem is used to calculate the heat generated by the dynamic friction of the water flow.It is analyzed that the aforementioned two types of heat losses slightly influence the measurement results,and the main source of heat loss is the heat conduction caused by the surface heat dissipation of the absorbing cavity.To reduce the heat dissipation of the absorption chamber,an insulation layer is covered outside the watercooling chamber layer to reduce the heat dissipation.The steadystate heat conduction formula of the cylinder wall is used to calculate the heat dissipation on the surface of the absorption cavity,which reduces the influence of heat loss to less than 0.1%and ensures that the thermal insulation performance of the system meets the requirements of the laser measurement.Results and Discussions To test the upper limit of the laser power measurement by the absorption cavity,the thermodynamic simulation of the cavity is conducted with an extreme ring heating model(Fig.2).When the laser power is 40 kW and water flow is 0.33 L/s,the maximum temperature of the absorption cavity is 477.97℃,which is excessively lower than the melting point of the red copper.Therefore,the laser power measured by the selfdeveloped device exceeds 40 kW.During the laser power measurement,it is determined that the temperature difference measurement exhibits certain fluctuations.To eliminate temperature field fluctuations,a temperature homogenization device is installed after the water outlet of the self-developed device.The comparison results of temperature measurement before and after treatment are shown in Fig.3,and the temperature fluctuation is within 0.01℃.Under the same laser power,adjusting the water flow rate can control the temperature difference between the inlet and outlet.As a larger temperature difference results in a smaller relative measurement uncertainty,the measurement uncertainty of the temperature difference can be reduced by controlling the water flow rate.The water flow rate is adjusted to 0.230 L/s and 0.029 L/s,respectively,and the temperature difference and power of the fiber laser with a wavelength of 1080 nm and spot size of 3 cm are measured at 1.4 kW(Figs.6 and 7).The test results show that the method for adjusting the water flow to modify the temperature difference is effective in reducing measurement uncertainty.Conclusions Based on the seven aspects of repeatability(Table 1),nonlinearity(Fig.5),surface uniformity(Fig.8),temperature difference of the measurement device before and after laser irradiation,flow measurement,temperature difference measurement,absorption coefficient measurement of the absorption cavity,and the uncertainty introduced by the laser measurement,the uncertainties are calculated and traced.The introduced uncertainties are 0.06%,0.51%,1.0%,0.15%,0.055%,0.43%,and 0.55%(Table 2).The final calculated extended uncertainty of the laser power measurement is 2.8%(coverage factor k=2).The measurement comparison between the selfdeveloped device and the optical pressure power meter shows that the normalized deviation value of the measurement comparison is less than 1(Table 3),indicating that the measurement results based on calorimetry are accurate and reliable.This suggest that it is initially possible to use the device as a measurement standard,laying a foundation for the subsequent establishment of highpower laser measurement standards.
作者
于东钰
杨心仪
李栋
俞兵
张云龙
尤越
吴沛
高宏
郭文阁
胡小菲
Yu Dongyu;Yang Xinyi;Li Dong;Yu Bing;Zhang Yunlong;You Yue;Wu Pei;Gao Hong;Guo Wenge;Hu Xiaofei(Optical Primary Measuring Station of National Defense Science and Technology Industry,Xi’an Institute of Applied Optics,Xi’an 710065,Shaanxi,China;Xi’an North ElectroOptic Science&Technology Defense Co.,Ltd.,Xi’an 710043,Shaanxi,China;Xi’an Military Representative Office,Land Aviation Bureau,Xi’an 710065,Shaanxi,China;School of Physics,Xi’an Jiaotong University,Xi’an 710049,Shaanxi,China;Faculty of Science,Xi’an Shiyou University,Xi’an 710065,Shaanxi,China;Xi’an Yufei Electronic Technology Co.,Ltd.,Xi’an 710065,Shaanxi,China)
出处
《中国激光》
北大核心
2025年第11期142-150,共9页
Chinese Journal of Lasers
基金
国家重点研发计划(2022YFF0606002)。
关键词
光学计量
高功率激光
量热法
量值溯源
不确定度
optical metrology
high power laser
calorimetry
traceability of quantity value
uncertainty degree
