Research On Lightweight And Miniature Multispectral Imaging System

At present,multispectral imaging technology is widely used in various research fields because it can simultaneously acquire target image information and spectral information.However,in the field of phenological observation,the observation equipment is required to have small size,light weight,wide spectral range,and high-quality images.Therefore,the performance of multispectral cameras needs to be continuously improved.This subject is aimed at the application of multispectral imaging system in obtaining vegetation space and spectral data.It adopts the snapshot multispectral imaging method with multiple apertures and one detector,and studies two lightweight and miniature multispectral imaging solutions.One solution is a multispectral imaging system that uses prisms to split the aperture.Inspired by bionic compound eye vision,compound eye imaging based on prisms is proposed.Firstly,from the three aspects of the mechanism of prism split aperture,the influence of prism dispersion and the method of achromatic dispersion that can be adopted,the feasibility of prism split aperture is verified.Using the method of ray tracing,a two-dimensional model of the prism is established,and the approximate linear range of the deflection angle of the prism is obtained.Secondly,the optical system design based on the prism aperture is completed.In order to achieve snapshot imaging of nine spectral bands,the structural parameters of the nine-sided pyramid prism and the angular relationship between the prism and the compensation mirror are calculated according to the principle of prism aperture.Analyze the effect of the aperture stop position of the objective lens on the uniformity of the image surface illumination.Select a mobile phone lens as the initial structure of the imaging objective,and optimize the design with Zemax optical software to obtain a large-field aspherical lens that meets the requirements of the index.The tolerance analysis of the optical system was carried out according to the method and principle given by the tolerance,and the feasibility of the design was obtained.Finally,the combined prism and the designed aspherical lens are used as the whole to analyze the imaging quality of the system,and the system is ray traced in Tracepro simulation software to verify the final design results to meet the detection needs of nine spectral bands.Another lightweight and miniature multispectral imaging scheme is to obtain thespectral information of each channel through the form of a Grin lens array combined with a filter array.First,according to the refractive index change formula of the Grin lens,the gradient lens profile is set in Zemax to complete the design of the optical structure of the subsystem.Then process and assemble it to complete the development of engineering prototype.The spectral calibration and radiometric calibration are carried out.The multispectral data cubes of nine channels and different wavebands are obtained,and the spectral response curves of each channel of the multispectral camera are fitted.Finally,the two lightweight and miniature multispectral imaging solutions are analyzed and compared,and effective improvements are proposed for the shortcomings of the design.