Optics Of Full-Spectrum High-Resolution Echelle Grating Spectrometer

As an important means to obtain material information,spectral technology has been widely used in space exploration,military science and technology,space remote sensing,biomedicine,environmental monitoring and many other important fields.Due to the large blaze angles and large grating constant,the echelle grating has high dispersion,high resolution and the characteristics of full spectrum blaze.It is commonly used in astronomical instruments or high-end commercial spectrometers The imaging system of the conventional echelle grating spectrometer is mainly a single reflector,which has the problem of uneven distribution of imaging resolution in the whole spectrum range,and the resolution at the edge wavelength is far lower than that at the center wavelength.In order to improve the overall resolution in a wide waveband range,the image plane homogenization method of echelle grating spectrometer is studied in this paper.The main contents include the following aspects:1.The off-axis three-mirror anastigmat system(TMA)is applied to the crossdispersion imaging optical path of the echelle grating spectrometer.The advantages of off-axis TMA system,such as no chromatic aberration,large field of view,high image quality and convenient optical path folding,is proposed to improve the overall spectral resolution in wide waveband range.2.A folded cross-dispersion optical path of echelle grating spectrometer is designed.The dispersion direction of the reflecting prism is perpendicular to the dispersion direction of the echelle grating,and the dispersive light is imaged on the image plane by TMA.The spectral band of the system is 200 nm-600 nm,and the simulation resolution is better than 30 pm in the whole spectrum range.The simulation results show that the application of TMA system can effectively improve the image quality at the edge wavelength and improve the overall resolution of the whole waveband compared with the optical path with a single parabolic mirror as an imaging mirror.3.The two-dimensional spectrum formed by the cross-dispersion of the echelle grating spectrometer is analyzed,and a spectrogram model is established for the oneto-one correspondence between two-dimensional coordinates and one-dimensional wavelengths in the spectrogram of the echelle grating spectrometer.4.An experimental platform is designed,an experimental optical path is built,and a spectrum measurement is completed.The experimental results show that the optical path of the echelle grating spectrometer combined with TMA is more uniform in the whole band range.Halogen lamp and mercury lamp are used as light sources.The spectral resolution of the system at 404.656 nm,435.833 nm and 546.074 nm is 27.20 pm,32.74 pm and 40.92 pm,respectively.