Study On Sub-diffraction Line-focusing Lens Based On Binary Amplitude-phase Mask

In recent years,with the development of the fields of biology,medicine,material and electronics,it is necessary to develop a technique of far-field super-resolution imaging and super diffraction focusing.However,due to the diffraction limit,the resolution of the focus spot and the white light(400nm-780nm)illumination imaging system is only half of the working wavelength.Therefore,it is of great scientific significance and application prospect to realize far-field super-resolution imaging and super diffraction focusing.In this paper,based on the idea of super oscillation,a new method of super diffraction far field focusing on two valued amplitude phase modulation is proposed;Based on the vector angular spectrum diffraction method and the particle swarm optimization,the transmission function of the line focus super oscillation device is optimized by using the two value amplitude phase modulation.Theoretical design of the device: focal length of 150?(94.9?m),focal spot half width of 0.38?(240nm),the sidelobe ratio of 25%;The simulation of line focus oscillation device using COMSOL super Multiphysics software,verified the focusing performance of the device,the device simulation results for a focal length of 150.24?(95.1?m),the half width of focal spot is 0.392?(248nm),sidelobe ratio is 23%;By using electron beam processing technology,complete processing device;finally using scanning probe on the devices tested,device test results: the focal length is 148?(94?m),the half width of focal spot is 0.406?(257nm),sidelobe ratio is less than 22%;analysis of the super oscillation criterion,the focal spot for super focusing oscillation.The main contributions of this thesis are listed as follows:(1)Introduce the background and significance of research on subdiffraction focusing,and detailed discussion about subdiffraction focus development at home and abroad,and the existing problems of science and technology,we propose design method of long focal length,small side lobe of focal spot.(2)This paper introduces the theory and the particle swarm optimization algorithm of linear polarized light vector angular spectrum diffraction.(3)The vector angular spectrum diffraction method and particle swarm optimization based on the two values of amplitude and phase control,transmission line focus on super oscillation device were optimized by ratio function,obtained the device two amplitude(0,1)and the two phase(0,?)distribution;and the use of COMSOL Multiphysics software,two the value of amplitude phase control line based on ultra focusing simulated oscillator.(4)A study of electron beam lithography system,dry etching,magnetron sputtering method of metal dielectric strip processing sub wavelength structure based on this basis,completed the processing device;and complete the experimental characterization of focal spot.