Super-resolution Optical Microscopic Imaging Based On Microsphere And Microprobe-microsphere

The resolution of conventional optical microscope can only reach half-wavelength of incident wave,due to the limit of optical diffraction.Various microscopies with super-resolution have been proposed and well developed in recent years.Among them,microsphere based microscopy has attracted great attention since it's able to realize super-resolution under white light illumination by just putting a microsphere on the surface of sample and is easy to operate.This technique supplied a simple and direct way for super-resolution imaging of nanostructures and vivo samples.However,present theoretical explanation of microsphere imaging is not clear and the methods still have some drawbacks.Therefore,further researches including imaging theories,methods and techniques are still required.In this dissertation,a novel multi-zone and super-resolution optical microscopic imaging method based on microprobe-microsphere is firstly proposed.All kinds of microprobe-microspheres are well prepared using a microscopic operation system.Experiments on various samples such as DVD,blue disk,and gratings are carried out and super-resolution images can be acquired at arbitrary sample regions.In addition,such a method can effectively avoid breaking the cantilever and damaging the microsphere or sample surface.This dissertation has developed a new method and technique of sub-diffraction-limit optical microscopy,and can be practically applied in various fields of micro/nano-scopy.The main content and innovation of this dissertation are as follows:A novel multi-zone and super-resolution optical microscopic imaging method based on microprobe-microsphere is firstly proposed.By combining microprobe(including micropipette and AFM cantilever)and microsphere,the displacement between sample and microsphere is controlled.In this way,multi-zone optical imaging with super-resolution is capable to achieve by the movement of microprobe and near-field information collection by the microsphere.Furthermore,"Soft-contact" between the microsphere and the sample can be constantly maintained owing to the elasticity of the AFM cantilever,so as to realize continuous super-resolution imaging during scanning.Meanwhile,such soft-contact can effectively protect the cantilever from breaking and decrease the possibility of damaging between the microsphere and sample surface.Mechanism of microscopic imaging with super-resolution based on microsphere and microprobe-microsphere is theoretically researched.The theoretical model of microscopic imaging based on microsphere is established and the traditional and near-field optical characteristics are analyzed respectively.Using the software ZEMAX and FDTD-solutions,the relationship among focus properties and microsphere's diameter,index inside and outside microsphere,wavelength and polarization of incident wave are simulated systematically and well discussed.Furthermore,the focus characteristics of single microsphere,microsphere array,microprobe-microsphere are further reported.All kinds of microprobe-microspheres are well prepared using the microscopic operation system.The system contains micro/nano scanner,microscope and some other devices.By combining the microprobe and microsphere using optical glue according to the micro/nano operation method,various microprobe-microspheres are made such as micropipette-combined microsphere,AFM cantilever-combined single microsphere,AFM cantilever-combined double microspheres,and so on.The microprobe can keep the super-resolution imaging ability of microsphere and realize the controlling of displacement between sample and microsphere,so that super-resolution images can be acquired at arbitrary sample regions.Besides,the microprobe can be used again and again if it is kept properly.A microscopic imaging system is established and super-resolution imaging experiments based on microsphere and microprobe-microsphere have been carried out.Microstructures of samples including DVD disk,blue disk and gratings can be significantly amplified with improved image contrast using various microspheres and microprobe-microspheres.Then by controlling the movement of microprobes,microspheres are able to scan across the sample surface to observe micro/nano-structures of samples in arbitrary interested region.