Study On The Planar Artificial Compound Eye Based On Metalens Arrays

Optical systems can adjust the optical paths,focus the incident light and produce images.They play an important role in the cameras,communication devices and detection equipment.Similar to the human eyes,the optical system currently used are usually single-apertured imaging systems that produce images from a single optical aperture.To improve the performance of the system,delicate optic designs,such as the combination of the concave lenses convex lenses,are introduced along the optical path to eliminate or reduce the aberrations.However,such devices are bulky and heavy,complicated design and optimization processes.In addition,the stacking of lenses along the optical axis limits the expansion of the field of view.In occasions where micritization,integration and large field of view are required,such as medical endoscope and fingerprinting,the traditional optical systems cannot complete the tasks very satisfyingly.For these scenes,the artificial compound eye systems based on the compound eyes of the biotic compound eyes of insects have attracted attentions of researchers.Different from the single-apertured optical systems like human eyes,the insects’ compound eyes are composed of numerous small eyes called ommatidium.Each ommatidia functions as an intact imaging system.The ommatidium can achieve a very large field of view because the ommatidium’s optical axis directions are different and thus aim for different directions.Based on the same principles,various types of artificial compound eyes(ACEs)are developed based,which can be classified as the curved ACEs and the planar ACEs.However,the current structures have many difficulties.On the one hand,the ACEs usually hard to realize because of difficulties in the designing or manufacturing process;On the other hand,their field of views are limited value that do not fully demonstrate the strengths of the compound eye structure.In addition,limited by the traditional optical materials,the large size of the micro lens array used in the ACEs affects the miniaturization of the ACE system.To handle the problems in the current ACE designs,a planar ACE based on the metalens array is proposed.It combines the metalens technology with the design of the ACE and successfully relieved of the limitation of the traditional optical materials,making the structural thickness reduced to wavelength scale.In addition,benefited from the multi-functional ability of metasurfaces,the metalens array can realize imaging and deflection of the incident light at the same time within a single planar structure.The deflection ability of metalenses allows them to aim for different directions of the field of view.With the combination of the sub-images of metalenses,the proposed planar ACE system can achieve a very large field of view.The main work of this thesis is as follows:(1)Under the basis of the analysis of the current ACE schemes,a planar ACE structure based on the metalens array is proposed.The structure can break through the limits of the traditional optical materials with the unique strengths of metalenses,making the proposed structure acquires large field of view while maintain a single-layered planar structure.(2)The metalenses are designed so that metalenses at different positions produce off-axis degrees that aim for different directions,realizing the focusing and imaging of different regions.The designing process mainly includes: the design and optimization of the unit structures in order to get a higher efficiency;The analysis and design of the surface phase of the metalens;The modeling of the designed metalens for the simulation verification.(3)Verification on the designed metalenses.Firstly,metalenses with different off-axis degrees are modeled using the CST software,and their electronic-magnetic response are calculated,in order to verify the field of view of a single metalens and its off-axis ability.Next,the light tracing performance of metalenses are further analyzed based on the ZEMAX software.