Research On Spectral Programmable And Large Field Imaging Technology

Since the 1970 s,more and more imaging spectroscopy has been applied to many fields such as environmental protection and geological prospecting.For the fact that the spectrum is different for different targets and the redundant spectral data are not helpful for late spectral analysist,the application departments have a strong demand for the large field of view imaging and low data redundancy imaging spectrometer.The lunar mineral spectrometer that will be carried by Chang'e 5 moon craft will use two-dimensional pointing to the surface of the moon for spectral imaging at 480 ~ 950 nm.The solution of the large field of view of the spectral imaging problem will provide an important basis of the analysis of lunar soil components.The main work and innovation of this paper include the following parts:1.Precise mathematical model of imaging module for lunar mineral spectroscopy On the basis of the general principle of the two-dimensional mirror imaging,the mathematical model of the optical transmission is established by combining the specific optical path of the imaging module of the lunar mineral spectrometer,and the transmission transformation parameters are obtained quantitatively.The geometric parameters of the two-dimensional pointing mechanism are precisely calibrated.The field angle of the instrument is measured experimentally.The optical transmission model of the detector image,the actual image and the azimuth and pitch angle is established.The relationship between the image rotation and the distortion of the azimuth angle is given quantitatively.Quantitative the analysis of the model error and the reasons are given quantitatively.This method has laid a foundation for obtaining large field spectrum image,which has certain innovation and engineering application value.2.Improved scale invariant feature transformation image automatic splicing technologyTwo-dimensional pointing mechanism for the near-field target imaging will obtain the rotation and distortion obviously.First,all the distorted images are corrected to the same horizontal plane according to the transmission transformation principle and the optical transfer model.Then,the corrected images are automatically stitched by the image stitching technique based on scale-invariant feature transform(SIFT).In practice,a large number of feature points mismatch caused by image quality,target similarity and so on,and the time wastage caused by feature points recognition in irrelevant regions are introduced,so the mathematical model of optical transmission is introduced into the algorithm.The algorithm is improved in the feature extraction phase,the registration phase,the transformation phase and the fusion stage,and the field test is carried out.The results of each step are analyzed,and several full-field spectral images and spectral curve results show that the method has some innovative and engineering application value.3.Ground-based full-field lunar observation experiment and prototype development A prototype is developed for the ground-based full-field lunar observation experiment,and the prototype is composed of the whole projection optical system.Different from the above-mentioned two-dimensional pointing mirror structure,the prototype adopts the whole machine to sweep the moon,and the algorithm is used to process the data.Finally,the lunar spectroscopy images and curves of the whole field are obtained.