Analysis And Measurement Of Distortion For Gratingimaging Spectrometer

The grating imaging spectrometer has the characteristics of good linearity,wide dispersion range,and can obtain the image and spectral signals of a target simultaneously.It is widely used in the field of remote sensing.Distortion(including smile and keystone)is one of the important parameters of the grating imaging spectrometer,which directly affects the quality of the image and spectral information obtained by the imaging spectrometer.Therefore,it is important to research,analyze and measure the distortion of the grating imaging spectrometer.Firstly,this paper summarizes the advantages and disadvantages of various imaging spectrometers,briefly describes the operational principle of the grating imaging spectrometers,and introduces the simulation and measurement methods for the distortion of the imaging spectrometer at home and abroad.The formula of the smile and the keystone of the plane grating imaging spectrometer are derived by using the theory of the vector diffraction.The cause of the distortion and its influence on the data acquired by the grating imaging spectrometer are illustrated.Then,the effects of distortion on the spectra and images acquired by the grating imaging spectrometer were simulated separately.With the evaluation criterion of the maximum spectrum deviation of 5% for the influence of the distortion on the spectral signal,the spectral response function of the Gauss type and the atmospheric simulation data are used to simulate and analyze the influence of the different amount of the smile on spectral signals when the spectral resolution is different in the visible and near-infrared(0.4~1μm)wavebands.With the assumption that the space response function is the rectangle function,the influence of the different amount of the keystone on spectral signal acquired by the imaging spectrometer is simulated by using the hyperspectral data.The amount of the maximum smile and keystone allowed by the system are obtained.By using the evaluation standard of the peak to noise ratio of 30 d B and the hyperspectral data,the influence of different amount of the smile and keystone on the image signal is also simulated and analyzed.On the basis of analyzing the advantages and disadvantages of the distortion measurement methods,a distortion measurement system for the grating imaging spectrometer of the Offner is proposed,which is “spectral line lamp + off-axis parabolic mirror + plane mirror + the imaging spectrometer under test + the detection with small pixel”.The feasibility of the measurement system is simulated and analyzed by Zemax and Solidworks software.Finally,the distortion measurement system is established,the distortion of Offner grating imaging spectrometer is tested and its measurement uncertainties are analyzed and evaluated.This work provides a technical basis for further development of the high fidelity imaging spectrometer.