摘要
针对目前大气透射仪校准领域无法溯源到世界气象组织对能见度定义的难题,以及如何实现满足国际民航组织(ICAO)观测要求的2700 K色温光谱模拟问题,本文提出了一种基于数字微镜的大气透射仪校准光源的光谱模拟方法。首先分析了光谱模拟单元的偏态性质,选用Bigaussian、Asym2Sig和ECS三种函数分别作为正偏态、正态以及负偏态分布光谱模拟单元的拟合函数;然后采用Gaussian函数以及Bigaussian、ECS、Asym2Sig三种函数组合进行光谱模拟对比实验,两者的光谱模拟误差分别为33.4%和25.2%,这表明三种函数组合代替Gaussian函数进行光谱模拟具有可行性;之后分析了影响光谱模拟误差的主要因素,提出了一种基于最大模拟误差的光谱修正方法,并在410~460 nm局部波段验证了光谱修正方法的正确性,最终实现了380~780 nm波段范围内2700 K色温光谱模拟误差为6.2%,较修正前整体光谱调制能力提高了4.06倍。
Objective The transmission visibility meter(TVM),being the main visibility measurement instrument,is calibrated based on the spectral characteristics of the detection light source,which does not satisfy the 2700 K color temperature light source standard defined by the Meteorological Optical Range(MOR)for visibility,making the instrument unidentifiable with the definition of visibility after calibration.Although the technical basis for 2700 K color temperature simulation is initially available,spectral simulation accuracy is low and it still cannot satisfy the requirements for TVM observation and traceability under the measurement accuracy of the International Civil Aviation Organization(ICAO).To address the current lack of a high-precision simulation method for 2700 K color temperature,this study proposes a spectral simulation method for calibrating the light source of TVM based on a digital micromirror for accurate simulation of the 2700 K color temperature spectrum.It also provides research basis and technical support for TVM calibration and traceability chain establishment that meets the definition of MOR and the standard of ICAO.Methods Forty-nine spectral simulation units are divided using the TVM-calibration light source experimental device.The Gaussian,Bigaussian,Asym2Sig,and ECS functions were used to fit three skew distribution spectral simulation units,based on the measured skewness properties of the spectral simulation unit.Three functions of Bigaussian,Asym2Sig,and ECS are selected as the fitting functions of the positive,normal,and negative skew distribution spectrum simulation units,based on the fitting accuracy.The feasibility of using Bigaussian,ECS,and Asym2Sig functions to replace the Gaussian function for the spectrum simulation experiment is proven using the 2700K color temperature spectrum simulation comparison experiment based on least squares.Three continuous spectral simulation units are selected at the wavelength where the maximum spectral simulation error is covered,and Lighttools software is used to simulate and analyze the reason for the large spectral simulation error.A spectrum correction method based on the maximum simulation error is proposed,and a local waveband experiment is performed to correct the spectrum simulation error and verify its correctness,based on the analysis of the influencing factors of the spectrum simulation error.The simulation error of the 2700Kcolor temperature spectrum after the experiment correction in the range of 380--780nm is measured by conducting a full-band spectrum correction experiment.Results and Discussion The Bigaussian,Asym2Sig,and ECS functions fit the spectral simulation units for positive,normal,and negative skew distributions,respectively.The residual sum of squares is all less than 1.5×10-3,the fitting accuracy of most simulation units is in the order of 10-4,the maximum fitting error appears at the simulation units with a peak wavelength of 600nm,and the residual sum of squares is 1.4×10-3(Fig.7).Comparing the experimental results of 2700Kcolor temperature based on least-squares spectrum simulation show that the spectrum simulation error using spectral Gaussian function fluctuates significantly,with a maximum spectral simulation error of33.4%at 388nm,the maximum simulation error using Bigaussian,ECS,and Asym2Sig functions is 25.2%at 431nm,and the spectrum simulation accuracy using a combination of the three distribution characteristic functions is higher than that using Gaussian function(Fig.8).The results of using the Lighttools software to simulate and analyze the spectral distribution on the digital micromirror array surface show that the spectral simulation unit has overlapping areas on the digital micromirror array surface,with each spectral simulation unit influencing one another,causing the overlapping area to be controlled by multiple proportional coefficients simultaneously.However,this does not comply with the principle that the scale coefficients of each spectrum simulation unit in the least-squares spectrum simulation principle are independent of each other.Therefore,spectrum simulation modulated by the principle of least-squares spectrum simulation has a low precision(Fig.9).The results of the experimental correction of spectral simulation error on the local band show that the spectral simulation error is 5.8%in the range of 410--460nm after the experimental correction.This implies that the spectral simulation satisfies the 2700Kcolor temperature spectral simulation error requirement under the 50mbaseline required by ICAO in the local band and that the maximum simulation error is used to verify the correctness of the spectral correction method(Fig.11).The results of correction studies on the fullband spectrum show that the maximum simulation error after correction is 6.2%,which is 4.06times larger than the overall spectral modulation ability before correction(Fig.12).Conclusions This study proposes a spectral simulation method for calibrating the light source of TVM based on a digital micromirror.The skew nature of the spectral simulation unit is analyzed,and Bigaussian,Asym2Sig,and ECS functions are selected to fit the positive,normal,and negative skew distribution spectral simulation units,respectively.The spectral simulation comparison experiment between using the Gaussian function and combining the Bigaussian,ECS,and Asym2Sig functions is performed;the spectral simulation errors of the two functions are33.4%and 25.2%,respectively.This shows that the Gaussian function can be replaced with a combination of three functions for spectrum simulation.The analysis reveals that the main factors influencing the spectral simulation errors are the presence of superimposed regions of spectral simulation units on the surface of the digital micromirror array and the lack of independent control of each simulation unit.The correctness of the spectral correction method based on the maximum simulation error is demonstrated using the local band of 410--460nm.The final simulation error of the 2700K color temperature spectrum in the band of 380--780nm is 6.2%,which is 4.06times higher than the overall spectral modulation capability before the correction;simulation accuracy of 2700Kcolor temperature spectrum corrected by experiment satisfies the ICAO observation accuracy requirements for the simulation error of 2700Kcolor temperature spectra at 50 m baseline and provides a research basis and technical support for establishing TVM calibration and traceability chain that satisfies the definition of MOR and the standard of ICAO.
作者
孙继亮
张国玉
张健
徐达
梁婧
运志坤
杨晓彤
Sun Jiliang;Zhang Guoyu;Zhang Jian;Xu Da;Liang Jing;Yun Zhikun;Yang Xiao tong(School of Opto-Electronic Engineering,Changchun University of Science and Technology,Changchun 130022,Jilin,China;Opto-Electronic Measurement and Control Instrumentation,Jilin Province Engineering Research Center,Changchun 130022,Jilin,China;Key Laboratory of Opto-Electronic Measurement and Optical Information Transmission Technology,Ministry of Education,Changchun 130022,Jilin,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2022年第11期159-169,共11页
Chinese Journal of Lasers
基金
吉林省科技发展计划(20190302124GX)
国家自然科学基金(62075019)
长春理工大学科技创新基金(XJJLG-2018-02)。
关键词
光谱学
大气透射仪
大气能见度
光谱模拟
黑体色温
校准方法
spectroscopy
transmission visibility meter
atmospheric visibility
spectral simulation
blackbody color temperature
calibration method