Research On Imaging Spectrometer Motion Compensation Implementation Technology

Imaging spectrometer is an important step forward in the development ofmulti-spectral imaging remote sensing technology, which significantly improved theremote sensing technology’s ability to detect the Earth’s surface features and objectsof nature, widely applied in military camouflage expose and mineral resourcessurvey. When the relative aperture of the imaging spectrometer is fixed, in order tosimultaneously ensure the ground pixel resolution and signal-to-noise ratio, motioncompensation technique is one of the optimum engineering implementationmethods.Aiming at Engineering development demands for spaceborne high-resolutionimaging spectrometer, the study of motion compensation implementation technologyhas been carried out. Firstly, the three imaging modes based on the scanning mirrormotion compensation have been compared and analysised. The distance and time oftheir observation have been calculated. Base on the preferred method, imageuniform motion compensation on the image plane, the theoretical curve of themotion compensation has been established and realization by the optimized method.Then the impact of scanning mirror assembly’s error terms on the image quality ofthe imaging spectrometer has been carefully analysised. According to the analysisresults, the scanning mirror assembly’s specification requirements can be resonalbly proposed. And then the scanning mirror assembly’s overall design with finite angletorque motor and high precision double channels’ Inductosyn is finished. After that,the scanning mirror assembly’s opto-mechanical structure has been designed,including scanning mirror mounting, shafting and base. FEA results indicate that thedesign is successful because of its stiffness and thermal adaptability. Afterward, thecurrent, speed, position closed-loop control system scheme has been proposed andsimulated by Matlab. Meanwhile the two key technologies of control system, highprecision current and speed control, have been detailedly analysised. Finally, thescanning mirror assembly engineering prototype is manufactured, assembled andtested.In the paper, Position precision non-contact measurement method, instantaneousspeed precision measurement method, the non-orthogonal error between the mirrornormal and rotation axis measurement method are proposed and excuted. The testingresults show that the scanning mirror’s surface error is1/50λ(λ=632.8nm，RMS),angle measurement accuracy is3.87″, position accuracy is4.5″, relative speedaccuracy is±5%, the non orthogonal error between the mirror normal and rotationaxis is15″. The finished scanning mirror assembly meets the developmentrequirements of space-borne high resolution imaging spectrometer.