Research On Compact Division-Aperture Snapshot Spectral Imaging System

At present,there is the urgent application requirement for the system that can be mounted on a miniaturized UAV(unmanned aerial vehicle)platform,which can capture real-time spectral image of moving object to recognize and track targets.So,based on a project,this thesis studies the compact division-aperture spectral imaging system.The system can capture spectral image imformation of moving object in real time,and has the merits of compact,lightweight and high frame rate.It can quickly recognize and track long-distance moving object,and can be mounted on a variety of platforms,with wild application prospects.In this thesis,different structure of the division-aperture spectral imaging system are compared and analyzed.According to requirements for specific task,a snapshot spectral imaging system based on the convergent optical division-aperture structure is proposed.Because it is the new system,threr are an in-depth research about this system: 1.According to Fourier optics,the transfer function characteristics of this system are studied.the overall system is modeled based on the imaging chain knowledge,and the imaging characteristics of this system are revealed.2.According to the aberration theory,the aberration characteristics of the convergent optical division-aperture system are studied,especially the chromatic aberration,which has an important influence on the spectral imaging system.The initial structural parameters of the overall system are determined.3.Based on the initial structural parameters of the overall system,a prototype of a compact division-aperture spectral imaging system was designed,and the prototype was laboratory-calibrated.In order to validate the performance of the system,on the one hand,it was mounted on the six-degree-of-freedom platform to carry out the simulation flight experiment,which demonstrated that the system has good stability.On the other hand,it was mounted on the moving ship to recognize and long-distance moving object in real-time,the expected result was obtained,The main innovations of this paper are as follows:1.A snapshot spectral imaging system based on the convergent optical division-aperture structure is proposed.The existing structure of snapshot spectral imaging system can't meet the application requirements.This thesis proposes a spectral imaging system based on the convergent optical division-aperture structure.The spectral imaging system of this structure is compact and lightweight,High frame rate,can meet the requirements of high-speed spectral image information acquisition for long-distance small targets,can be mounted on small UAV or cubic satellite platform with size limitations.The system greatly.expands the application fields of spectral imaging technology2.A stray light suppression structure with a tilted 9 aperture is proposedIn the convergent optical division-aperture structure,because of the compact structure,it is impossible to locate the field stop,the image of each channel outside the field of view will overlap seriously at the image plane,so that the image obtained on the detector can't be used.In this thesis,a structure of a tilted 9-aperture stop is proposed,by analyzing the stray light characteristics and structural characteristics of the system.This form of stop is located between the rear lens and the image plane.In the every channel,the stray light outside the field of view of is suppressed effectively.Each aperture has a certain inclination angle.When the light outside the field of view is suppressed,the light in the field of view is effectively ensured.The effectiveness of this stop is verified by software simulation and experiment.3.a laboratory calibration scheme for a compact division-aperture spectral imaging system is proposed.For the new structural form of the spectral imaging system,the existing calibration scheme can't meet the calibration requirements of the system.Based on the in-depth analysis of the system characteristics,this thesis proposes a laboratory calibration scheme for the spectral imaging system,including spectral calibration,relative radiometric calibration,and absolute radiometric calibration.By segmenting the image on the detector,the calibration coefficients of different spectral band in different channels are obtained.When the spectral data are restored,different calibration coefficients in different spectral bands are corrected respectively.Finally,a better result of spectral imaging data is obtained.