The Opto-mechanical System Design Of Visible-shortwave Solar Irradiance Spectrometer

Solar radiation changes on the Earth's environment is huge,monitoring solar radiation providing great convenience for human production and life,and protecting the environment according to local conditions,so as to promote harmony between man and nature.Due to technical reasons,solar radiation monitoring presently is mostly concentrated in the total solar irradiance,while monitoring the solar spectral irradiance makes slow progress and is lack of strong data.Due to the Earth's water,atmosphere,land and so on with selective absorption,it is urgent to develop instruments to monitor the changes of solar spectral radiation.In order to solve this problem,the optical spectrum and mechanical structure of the instrument are designed,and the spectral calibration and radiometric calibration of the instrument are carried out.Firstly,solar radiation measurement principle and instrument commonly used evaluation parameters are analysed.According to the performance of the instrument f(?)ry prism is selected when it compares the advantages and disadvantages with other spectroscopic element.According to the characteristics of prism structure,the prism angle of front and rear surface is calculated and the incident angle is also calculated.In order to achieve solar radiation measurement of spectrum from 400nm to 2500nm,the main optical path uses a mirror to scan and detectors collect the signal.In order to improve the measurement accuracy of the main optical path,the reference optical path which include the laser light,the concave mirror and the CCD detector are used to calibrate the instrument.According to the optical principle,two optical path forms are designed and optimized and the characteristics of the two main optical paths are compared.The optimal optical path scheme is determined and a reasonable optical design scheme is obtained.Secondly,according to the optical path program and the optical components,the sophisticated mechanical structure is designde to fix optical element.According to the outdoor's environment,Sealing structure are designed.The mechanical structure is analysed and mechanical stress and strain are obtainde.The instrument's frequency which is natural is simulated by software,so we can obtain reasonable structure and avoid natural frequency when the instrument is used.Finally,the laser was used to perform the spectral calibration experiment on the visible and infrared bands of the instrument.The high precision calibration of the instrument is realized by combining the experimental results with the prism dispersion equation and the results show that the spectral calibration uncertainty is better than 0.5nm.standard lamp is used to calibrate radiation of the instrument.The calibrated instrument is placed outdoors and the results are in agreement with the modtran4's simulation.The instrument is reliable and safe with outdoor's operation,showing the rationality of the design.