Hyperspectral imager is easily affected by noise in the process of imaging, so it is difficult to evaluate the noise in it. It is difficult to obtain accurate image noise values by existing technical methods, and it is also a problem to correct different environmental light sources.In this paper, by comparing the reflectivity inversion results obtained from the inversion of different number of reflectance plates.Inversion method based on the double reflectance plate is the best choice finally. The mean square error of the reflectance spectrum and the calibration spectrum obtained from the inversion in the band of 500~900nm is less than 0.0001, which effectively corrects the radiation error in the image.Based on PCA and SVM algorithm to build the grain heavy hyperspectral classification model.The improvement of the total accuracy and test accuracy of the inversion model based on double reflectance plate is better than several other inversion methods.Compared with single reflectivity inversion reflectance spectra, inversion method based on the double reflectance plate build hyperspectral database after training to obtain a set of test precision of 4.409%, total classification accuracy of 3.104%.
In ultraviolet spectroscopy, there is a constant need to improve the diffraction efficiency. A blazed
grating can concentrate most of the light intensity into a desired diffraction order, so it is the optimum
choice among gratings of different kinds of profile. As the operating wavelength of most UV spectral
applications is less than 200 nm, the required blaze angle is small; groove irregularity and surface
roughness of nanometer magnitude can cause a significant loss of diffraction efficiency. Therefore, it is
important to control the groove shape precisely , especially the blaze angle and the apical angle.
We have presented a direct shaping method to fabricate EUV blazed gratings by using an ion-beam
mixture of Ar+ and CHF2+to etch K9 glass with a rectangular photoresist mask. With this method, we
have succeeded in fabricating well-shaped UV blazed gratings with a 1200 line/mm groove density and
8.54° blaze angles and 1200 line/mm groove density and 11.68° blaze angles, and the metrical
efficiency is about 81% and 78%. The good performance of the gratings was verified by diffraction
efficiency measurements. When one uses the etching model, the conditions on the ion-beam grazing
incident angle and the CHF3partial pressure should be noted. Besides, since the etched groove shape
depends on the aspect ratio of the photoresist mask ridge, if we wish to fabricate larger gratings with
this method, we must improve the uniformity of the photoresist mask before ion-beam etching.
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