Data Processing And Software Implementation Based On Circular Variable Filter Spectrometer

Spectroradiometers are mainly used to measure the spectral characteristics and radiation brightness of radiation sources.The Circular Variable Filter(CVF)type spectroradiometers has the advantages of a wide spectral range and a large target temperature measurement range.However,research on CVF spectroradiometers in China is relatively late,and there is also relatively little research on their data processing methods.Data processing methods are crucial to ensure the accuracy of measurement results,so it is important to conduct data processing research based on the characteristics of CVF spectroradiometers.The focus of this article is on the spectral characteristics and error sources analysis of the CVF-type spectroradiometers,as well as the research on data processing algorithms that combine instrument characteristics(including data pre-processing,wavelength registration,and radiation calibration),and the design and implementation of measurement control and data processing software.Through three aspects of research,the aim is to improve the measurement efficiency and data analysis capability of the spectral radiometer.Firstly,this article provides a detailed description of the CVF theory and the optical path characteristics of the spectroradiometer,which provides theoretical support for subsequent research.The spectral characteristics of CVF are analyzed,and simulated experiments are conducted to analyze the errors in the measurement.The results show that CVF drift can cause wavelength mismatch and spectral distortion.To address this issue,preprocessing methods are explored,and cross-correlation and cyclic shift correction are used to correct data drift.After analyzing the experimental results,it was concluded that the covariance cross-correlation method was superior to other cross-correlation methods.This method can effectively correct the drift problem,and the mean deviation is reduced from 23.9 to 1.3 sampling points before and after drift correction,providing stable and effective data assurance for subsequent calibration work.The second part of the article focuses on the wavelength re-calibration and radiometric calibration of the CVF spectroradiometer based on its own characteristics.To address the wavelength misalignment issue,a rough re-calibration is performed using the starting position and step number of the stepper motor,as well as their relationship with the CVF wavelength.The re-calibration is then validated using the absorption peak position of CO2 atmospheric transmittance calculated by the HITRAN molecular spectral library and MODTRAN radiative transfer software.As a result,the error of the re-calibration is reduced from 0.95%to 0.2%of the wavelength.To solve the problem that the traditional radiometric calibration method cannot guarantee the accuracy of radiometric calibration due to the wide wavelength range and temperature range of the measurement target,a radiometric calibration model based on the optical path characteristics of the radiometer itself is analyzed,and a segmented linear method is proposed for radiometric calibration.The deviation of the calibrated equivalent temperature is less than 2%of the target temperature.By analyzing the uncertainty components and synthesizing calculations,the uncertainty of radiometric calibration is calculated.The final radiometric calibration composite uncertainty of the radiometer in the two detector response wavelength ranges is 3.1%(1.3～5.5μm)and 3.2%(5.5～14.3μm),respectively.Finally,a measurement control and data processing software is designed and implemented.The software can achieve functions such as measurement,control,data analysis,and data saving of the instrument,thereby greatly improving the efficiency of the experiment.The software’s modules and interaction interfaces are designed and implemented,based on the steps of experimental operation logic,data processing flow,and result display.Additionally,we developed a communication method and protocol between the instrument and software to ensure real-time,correctness,and stability,while optimizing data reception and processing.Through the design of object-oriented classes,the logic of the software is implemented,and the storage structure and database are constructed.Finally,the functionality of each module of the software is tested to ensure the correctness and effectiveness of the software use.