Research On System Integration And Spectral Restoration Experiment Of Coded Aperture Imaging Spectrometer

Spectral imaging technology combines the advantages of spectral technology and imaging technology,and it can get three-dimensional data cube composed of two-dimensional information and one-dimensional spectral information of target scene.Spectral imaging technology can not only conduct qualitative and quantitative analysis,but also conduct located analysis.It has great application in many fields.However,most airborne imaging spectrometer is dispersive spectrometer with pushbroom,witch light flux and resolution restrict each other.Although the interferometric Fourier transform spectral imager has relatively high spectral resolution,it still needs to scan,can not realize real-time imaging.The coded aperture imaging spectrometer has the advantages of high luminous flux and multi-channels,and has the capable of staring imaging.It can effectively inhibit the background information and the interference signal through the modulation and demodulation,enhances the required spectrum signal and obtain high signal-to-noise ratio.It uses two-dimensional data detection to realize the sampling of three-dimensional data cube,comparing with the traditional imaging spectroscopy,the amount of data it needs to measure is much smaller,which greatly reduces the pressure of storing and transmitting the data.Therefore,the research of coded aperture imaging spectroscopy has become one of the frontier research topics in the field of international spectroscopy analysis and detection.The main work of this article includes the following three parts:(1)The system structure design and adjustment integration are carried out.Through the full investigation and futher study of the coded aperture imaging technology,the design of the system structure is completed,at the same time,there is a multi-optical axis generated by multiple reflections in the optical path and an angle between the actual work surface and the assembled work surface of the coded aperture device,in order to meet the challenge of system adjustment,this paper proposes theuse of a combination of laser reference positioning and the principle of refractive reflection of the light to adjust the system,and finally completes the construction and integration of the experimental platform.(2)Corresponding the encoding template and detector with “ regular stripe combined with image processing correction method”.In the coded aperture imaging spectrometer,the registration of the coded template and the detector pixel affects the accuracy of the coding and the quality of the spectrum reconstruction.The existing solution usually uses a method of adjusting the position of the detector until it become symmetrical with the coded aperture device,However,this method will cause defocus of the edge field of the detector and reduce the utilization of the target surface.To solve this problem,this paper proposes a method that using “regular stripe combined with image processing correction method” to process the unavoidable asymmetric deformation error in the system structure,through the comparative analysis of the ideal regular stripe and the image detector collected,quantitatively calculating the deformation of the pixel in order to achieve correction.The method can basically restore the theoretical value of the corrected image under the condition of ensuring the full field clearly view of the detector,and solve the registration problem of the coded aperture device and the detector.(3)Spectral restoration experiments are carried out and optimization design of decoding algorithm is proposed.A coded spectral imaging experiment was carried out on the experimental platform where the adjustment was completed,and the 7th-order restoration spectrum of the target scene was obtained by decoding and recovering the collected data information.In order to further improve the spectral resolution of the system,the rear telecentric lens in the original structure is replaced by a zoom lens,and analysed the changes of spatial resolution and spectral resolution in different matching relationship.In order to improve the real-time performance of the system and reduce the decoding time of the high-order coded aperture,the method of decoding the data using symmetric ? transform is proposed,and complete the algorithm design.In this paper,through the system adjustment and experimental analysis of the coded aperture imaging spectrometer,the feasibility and superiority of the coded aperture imaging technology are verified.By studying on the key technologies,improved the accuracy of encoding,and provide technical accumulation and theoretical reference for the study of the coded aperture imaging spectrometer.