Reserach On Multi-focusing Bionic Compound Eyes

The eyes are the visual organ of biology,which is the main way for most organisms to obtain information from the outside world.According to the different imaging features,the eye can be roughly divided into two categories: the single eye and the compound eye that most insects possess.It has been found that the compound eye has unique optical properties: small size,light weight,large field of view,high sensitivity and polarizing character.This allows it to have an advantage over the single-vision system in many areas.Due to its wide potential application,more and more researchers are engaged in the research of bionic compound eye.On one hand,new process,new structure,new materials and others are used to design the new fabrication method of bionic compound eye.On the other hand,the imaging features of bionic compound eye are used to investigate new applications and related derivative applications.Focus on the mismatching between the present curved bionic compound eye and planar detector,this paper proposed a multi-focusing bionic compound eye structure,and the corresponding fabrication technology and image processing method.This paper centers around the following aspects:(1)Firstly,we has conducted the thorough research on biological compound eye.Analytical investigation of the structural and functional characteristics,and the imaging principle of compound eye were expounded.Based on the study of biological compound eye,the optical components corresponding to each structure are abstracted and the corresponding optical prototype is established.According to the imaging modality of compound eye,the corresponding parameters are calculated and the mathematical model of the compound eye is established.Finally,an optical simulation model is established by the optical design software.After that,based on the simulation model,a series of simulations are carried out to invesigate the imaging characteristics and optimize the structure.Then the main aberration of bionic compound eye and the corresponding compensation method were analyzed in detail,as well to further improve the structural design.Base on the above research,a multi-focusing bionic compound eye model was established to solve the mismatching between curved microlens array and planar detector array.(2)Two fabrication methods of microlens array were proposed based on the design of bionic compound eye structure.The main technologies are soft lithography technology,3D printing technology and negative pressure forming technology.In the process of soft lithography,the preparation of multi-focal microlens array is realized by mask design.And the self-designed injection mold makes the substrate accurate and controllable.Based on the 3D printing technology and compression molding technology,the rapid prototyping of bionic compound eye with sandwich structure is realized.The microlens array of the structure is distributed on the curved substrate,which sandwiched between the inner and outer layer.Furthermore,the inner and outer layers are respectively the self-assembled micro-holes array and the one prepared by secondary injection.This structure can effectively eliminate the interference of stray light and the crosstalk between neighbors.Due to the simple process,short period and low cost,it is beneficial to mass production,which promote the practical application of bionic compound eyes.(3)Lastly,based on the study of large field imaging based on bionic compound eyes,a large field image-stitching algorithm was proposed by using the SIFT operator and multiple homography matrix.The robustness and the ability to stitch large field images are validated through the imaging experiments.Experiments show that the algorithm has good robustness under various interference factors and can realize image stitching under large field of view.