Research On Spectral Data Acquisition And Signal Restoration Method Based On Transmission Grating

Thanks to the development of today’s information age,spectral analysis technology has shown irreplaceable importance in practical engineering applications,and spectral instruments have also been continuously developed.Portable spectrometer overcomes the shortcomings of traditional spectrometer,such as bulky and inconvenient to carry,but it also has the problem of poor performance due to its own limitations.Based on this,this thesis proposes to design a low-cost,miniaturized portable spectrum system with transmission grating as the light splitting element and smart phone instead of the traditional PC,and use data processing means to restore the spectrum signal to explore the possibility of improving the resolution of the portable spectrometer.Firstly,based on the basic composition theory of spectrometer,a set of spectral splitting system based on transmission grating is designed and built.With smart phone,spectral data of different light sources with wavelengths ranging from 400 nm to 700 nm can be collected.Based on the calibration of brightness response curve of mobile phone camera,the corresponding relationship between pixel value and relative radiation intensity is obtained,and the mapping relationship between chromaticity coordinates and arbitrary non-pure color light wavelength value is found by using color conversion matrix and chromaticity diagram to realize the conversion between pixel value and wavelength,thus completing the inversion of spectral distribution;Secondly,according to the characteristics of the designed spectral system,Gaussian model is selected,and the instrument response function of the system is obtained by measurement.According to the imaging characteristics of the spectral system,Richardson-Lucy deconvolution algorithm is selected as the spectral signal restoration method.The loss of illumination distribution of light sources with different Gaussian distributions through the simulation beam splitting system is restored by the algorithm,and compared with the illumination of the original light source without the simulation system.Based on the simulation,the effectiveness of the restoration algorithm in the transmission grating spectrum system is illustrated.Finally,the system software is developed based on Android studio,and the spectrum curve is displayed on the smart phone interface.At the same time,the system is used to collect spectral data and restore signals of laser pen light sources with wavelengths of 450 nm,532 nm and 650 nm,respectively.It is found that the full widths at half maximum of the spectral curves of the three light sources are narrowed,the intensity of spectral peaks is improved,and the corresponding wavelength positions of spectral peaks are closer to the real wavelength positions.Compared with the spectral data restored by filtering out 50%light intensity,the accuracy and stability of R-L deconvolution algorithm in spectral restoration of transmission grating spectral system are verified.The research shows that the spectral distribution obtained by the inversion of transmission grating spectral system considering the imaging characteristics of mobile phone camera is more accurate,and the spectral signal recovery by data processing means is effective to improve the resolution of the system.The relevant conclusions obtained in this thesis can provide some reference ideas for solving the problem of poor performance of portable spectrometer.