Research On Precision Machining Of Multi-focusing Curved Bionic Compound Eye Via Two Photon Polymerization And Detection Technology

Biological compound eye has unique advantages in visual imaging.It has a larger field of view,is more compact and sensitive to motion.These properties have attracted the interest of many researchers.Curved bionic compound eyes have been prepared by imitating the structure and function of the biological compound eye,and have been widely used in many fields such as target recognition,medical imaging,dynamic monitoring and panoramic imaging.However,the current curved bionic compound eyes have problems such as large size,insufficient compact structure,complicated processing and defocusing at edges of image field,which make them limited in micro vision applications.To solve these problems,a simple multi-focal length curved bionic compound eye with negative meniscus base is proposed in this paper,and the following research work is carried out.(1)Structure design of multi-focusing curved bionic compound eye.A multi-focusing curved bionic compound eye with negative meniscus base is proposed.The effects of different curvature radii and thicknesses of substrates on light focus are studied by optical simulation,and the geometric parameters of substrates are determined by comparing the size of focusing spots.By designing the curvature radius of the microlens,the focal length of each microlens is adjusted,and the light focusing of the curved bionic compound eye is realized in the plane.The uniform focusing intensity of microlens in bionic compound eye is demonstrated by optical simulation.It is proved that the design structure solves the defocusing problem of curved compound eye.The imaging quality of the design structure is evaluated by using point diagram and optical transfer function,and it is proved that it meets the imaging requirements of optical system.The effectiveness of negative meniscus base in reducing spherical aberration is proved by comparing with contrastive bionic compound eyes.(2)Structure processing of multi-focusing curved bionic compound eye.As a micro and nano processing technology,two-photon polymerization technology has high manufacturing accuracy and excellent 3D processing ability,which is a powerful tool for the fabrication of curved bionic compound eyes.In this paper,two-photon polymerization technique is used to fabricate multi-focusing curved bionic compound eyes.The effects of different scanning modes,machining paths,laser power,scanning speed and layering thickness on the surface quality are investigated.The experimental results show that the optimal structure quality is obtained when the laser power is 69 m W,the scanning speed is0.02mm/s,and the layer thickness is 0.2μm.The multi-focusing curved bionic compound eye is fabricated by using the optimal processing parameters.(3)Optical detection of multi-focusing curved bionic compound eye.Scanning electron microscope and white light interferometer are used to detect the machined structure.The optical focusing and optical imaging detection are carried out on the multi-focusing curved bionic compound eye and the contrastive bionic compound eye respectively through the optical detection platform.The detection results show that the multi-focal length curved bionic compound eye proposed in this paper has better focusing ability,effectively solves the defocusing problem of curved compound eyes,and improves the image quality of the edge.The modulation transfer function of multi-focusing curved bionic compound eye is measured by using the imaging images captured by bionic compound eye,the resolution of the bionic compound eye is proved to be better than that of the contrast bionic compound eye.The image registration algorithm and image fusion method are studied,and SURF algorithm and image fusion method are used to splice the sub-images captured by the bionic compound eye.