Research On The Design And Image Process Of Bioinspired Spherical Compound Eye Imaging System

In nature,there is an excellent class of vision system – compound eye,which is widely exist in arthropods,such as bees,fruit fly and dragonfly – except of human's single lens eye.Unlike human eyes,compound eyes consist of hundreds to thousands of integrated optical units,called ommatidia,arranged on a convex curved surface.Compound eye in nature is a remarkably sophisticated class of imaging system,which offers a larger field of view with negligible distortion and aberration,higher acuity to motion and a smaller package than human's single lens eye.These features enable the compound eye imaging system to have a great potential for a broad range of applications including surveillance imaging,target detection and tracking,surveying and mapping,collision-free navigation of terrestrial and aerospace vehicles and so on.The compound eye imaging system has attracted great attentions due to its fascinating optical features such as large field of view(FOV),small volume and high acuity to moving objects.But due to the limitation of the manufacturing process and the planar based imaging sensors,most of the work focused on the development of planar compound eyes in the past two decades.Even though more efforts are made on the fabrication and realization of curved compound eyes in recent years,they can only obtain an image with low resolution and couldn't meet the requirement for those applications with requirement on a relatively high-resolution image.Based on the study of the natural compound eye,a design principle of artificial compound eye is proposed.Artificial compound eye is divided into two class: structural bio-inspired compound eye and theoretical bio-inspired compound eye.And theoretical bio-inspired compound eye consists of multi-camera bio-inspired compound eye and ray-transferred bio-inspired compound eye.In addition,some typical functions were proposed,such as a wide field of view image,fast target detection and recognition,and so on.Here we presented two different bio-inspired compound eye camera system: bio-inspired micro-lens compound eye called SCECam,and bio-inspired milli-lens compound eye.Each camera system consists of the same three sub-systems,namely,hemispherical lens array,an optical relay device,and a planar photoreceptor with a data signal progressing module.The SCECam can realize a large FOV(up to 122.4°)with 4400 ommatidia,which makes it possible for detecting and locating fast moving objects at a very fast speed.The prototype milli-lens compound eye,which contains 117 ommatidia,has the ability of capturing a wide field of view of up to143.6°.The novelty of this work includes four aspects:1.A design principle of artificial compound eye is proposed.We modelled the structure of artificial compound eye and derived the parameter constraint conditions.Some new features of the two compound eye imaging systems which is able to locate objects at a wide FOV and recognize objects with a high speed were proposed.2.Two implement methods of artificial compound eye were proposed,structural bio-inspired compound eye and theoretical bio-inspired compound eye.3.Different from previous work,an optical relay system is introduced into these two compound eye imaging systems and deployed in between the hemispherical compound eye and the imaging sensor to transform the curved focal plane into a planar focal plane for image receiving.4.The good imaging ability of the two compound eye imaging systems is validated,and an inverse-imaging reconstruction method was developed to restore a complete image from hundreds or thousands of sub-images.