Research On Error Analysis Of Wavelength Scanning Mechanismand Wavelength Calibration For Scanning Grating Spectrometer

As one of the main spectrometer parameters,wavelength accuracy is an important index for the evaluation of the spectrometer performance,and there are many factors that affect it.In order to meet the requirements of home-made near-infrared wavelength precision,based on scanning mechanism of the dispersive grating spectrometer,the errors which exists in the scanning mechanism are analyzed,and the wavelength error and the wavelength compensation method are researched,which provides a feasibility plan to improve the wavelength accuracy of the spectrometer.According to the structure and principle of home-made portable grating spectrometer,on the basis of dispersion formula of the plane grating,determining the source errors in the scanning mechanism,which are optical zero error and roller guide alignment error,then a detailed mathematical analysis model of error for splitting system emission wavelength and the scanning mechanism error is built;Based on the characteristics of the scanning mechanism,determining compensation parameters of wavelength error,and the mathematical model of wavelength compensation is established.On the basis of the compensation model,the wavelength compensation scheme which includes model parameters solving and compensation parameter optimization is presented.The methods of model parameters solving are simultaneous equations and particle swarm optimization,and the methods of demining the compensation parameters are respectively rod length ratio optimization and hardadjusted-soft-repaired based on compensation parameters.To MATLAB GUI as a tool,the software which is based on wavelength error model and its parameter optimization is developed.The experiments of error parameter solving based on simultaneous equations and wavelength compensation by using monochromator have shown that,comparing with the original ±2.6nm,the wavelength accuracy after compensation is improved to ±0.3nm,then wavelength accuracy of the compensation method is enough for the monochromator;The experiments of error parameter solving based on particle swarm optimization by scanning grating spectrometer have shown that after compensating,the wavelength accuracy is better than 1 nm,which satisfies the requirements of spectrometer accuracy.The two experiments above have verified the correctness of the error analysis of the spectrometer scanning system and the validity of wavelength compensation method.