Research On Key Technology Of Biomimetic Curved Compound-eye Imaging Optical System

The traditional single-aperture imaging system exhibits the high resolution while suffers from its little space information of images,causing limitaions in the application of long distance,large field of view(FOV)and multiple dimensions imaging.To solve this problem,biological compound eye systems are emerged as the times requires,which benefits from its large field view,compact optical structure and rich spatial information,attracting widespread interest in air defense and early warning,machine vision,tracking and positioning of moving target technology.Classical extended FOV biomimetic compound-eye systems are made from camera array and curved microlens array.Compared with the compound-eye systems manufactured by camera array,it has the problems of huge volume,synchronization,and real-time for data acquisition.Compound-eye systems made by curved microlens array are still in the laboratory platform with unideal imaging results.Wide FOV,low distortion imaging and multi-dimensional information detection of biomimetic curved compound-eye technology become one of the hottest topics recently.This dissertation focused on the study in the imaging technology of biomimetic compound-eye,proposed the corresponding solutions and technical routes for the exisiting issues and technical difficulties of the biomimetic compound-eye imaging system.The main research works are as follows:First,this dissertation derives the constrained relationship of the related structural parameters for large FOV imaging and moving target recognition and tracking in the model of the biomimetic curved compound-eye.The compact biomimetic curved compound-eye technology with large FOV is presented after studying the imaging principle of the biomimetic compound-eye.According to the characteristics of the biomimetic curved compound-eye,some new typical functions have been investigated,such as large FOV imaging,moving target recognition and tracking.Second,this dissertation proposed the design scheme of the biomimetic curved compound-eye imaging system.In general,the system developed in this research consists of a curved compound-eye lens,an optical relay subsystem,and a high definition COMS.Among them,the compound-eye lens is composed of a lens array and a supporting hemispherical shell.The lenses are typically densely arranged on a hemispherical metallic shell in a way of hexagonal layout,like a honeycomb.This arrangement expands the detection range of the biomimetic compound-eye imaging system,and the overlapping FOVs between adjacent ommatidia ensures that the target in the object space can be simultaneously detected by the system from different angles.Therefore,both image information and depth information are recorded on the image sensor in real time that are essential for subsequent compound-eye image retrieval,distant target detection,and motion trajectory tracking.An intermediate optical relay subsystem is also proposed to transform light into a flat focal plane,fitting for the CMOS and assuming the task of correcting optical aberrations.In addition,the data of each ommatidium is acquired by the same CMOS to avoid the synchronization shortcoming for data collection.Third,this dissertation developed a compact biomimetic curved compound-eye imaging system for UAV-borne remote sensing,which mainly includes the design of the compound-eye lens and the optical relay subsystem,the tolerance analysis for overall optical system,and the analysis of the direct assembly of the lens array.Then the imaging performances of the biomimetic compound-eye system prototype were tested,and the experimental results show that the developed biomimetic curved compound-eye imaging system has a FOV of 98°,a system focal length of 5 mm,an angular resolution of 1.8 mrad and an F-number of 3.5.The overlap rate of the FOVs between two adjacent ommatidia is about 39%.The Modulation Transfer Function(MTF)values of each imaging channels are greater than 0.27 at a spatial frequency of55 lp/mm.The relative distortion of the edge FOV is less than 1.97%.The size of the system is Ф123 mm × 195 mm,and the weight is 1.35 Kg.The above designs provide a reliable hardware method for realizing a large FOV,low distortion and distant detection of moving targets purposes.Finally,this dissertation carried out initial airborne tests based on the developed biomimetic curved compound-eye imaging system prototype,receiving the experimental results of large FOV imaging,distant moving target detection and trajectory recognition under different environmental backgrounds.The test results are explored preliminary as a potential application of unmanned aerial vehicle remote sensing proving its miniaturization and integration of biomimetic compound-eye imaging system.At the same time,it is verified that the biomimetic curved compound-eye imaging system could realize the detection and tracking of wide-area moving targets under airborne conditions.This dissertation developed a biomimetic curved compound-eye imaging optical system that is effective in tracking and recognizing the trajectory of long-distance moving target,which is expected to promote our country’s key technological breakthroughs in the novel compound-eye imaging field.