| Optical microscopy is an important way for us to understand the micro world,and it has important applications in natural science research fields,such as biology,medicine and industry.However,due to the diffraction limit,the resolution of traditional optical microscope system is limited in half wavelength.Therefore,scientists have been devoted to research the super-resolution imaging technology of optical microscopy,and have achieved many outstanding achievements,such as light activated localization super-resolution imaging technology,structured light illumination super-resolution imaging technology,and stimulated radiation loss fluorescence super-resolution imaging technology,et al.However,the super-resolution microscopy imaging system based on the current technology has some problems,such as complex design,large volume,high cost and difficult integration.For different technologies,there are still some defects,such as time-consuming imaging process,complex image reconstruction algorithm,fluorescence characteristics of samples and so on.In this paper,a light field adjusting method with micro nano devices for super-resolution microscopic imaging is proposed.The micro nano device has the advantages including flexible design,small volume and easy integration,and regulating multi-dimensionally the light field.The illumination light field,object plane light field,imaging plane light field,and objective lens light field chromatic aberration of optical microscopic imaging can be adjusted respectively by the micro nano devices,which not only improve the resolution of the microscopic system,but also expect to lay a theoretical foundation for the integrated assembly and miniaturization of microscopic imaging system.The main research works is as follows:(1)Based on super-diffraction focusing characteristics of microsphere lens,the regulation of the light field of the object plane by microsphere lens for super-resolution microscopic imaging is studied.Firstly,the super-resolution imaging theory of hollow microsphere lens is studied,the results show that hollow microspheres can establish a high effective numerical aperture through the light focusing characteristics of solid microspheres,which makes the focusing spot changed longer and thinner,simultaneously,the focusing spot is compressed to λ/5.The super-resolution imaging of the hollow sphere is been verified by experiment.Second,the matching relationship between the refractive index of microsphere and immersion liquid is studied,the model is established and simulated,and the result is consistent with the theory.Finally,the super-resolution imaging ability of non-spherical microlens is verified by experiment,which broadens the application of the method because the non-spherical microlens does not need to buy commercial microsphere.(2)The traditional devices of generating vortex beam have the problems of large volume and difficult integration,a method of adjusting the light field of vortex illumination for superresolution microscopic imaging driven by metasurface is proposed.Firstly,the theory of super-resolution imaging with vortex illumination beam is studied,and the model is constructed.The main parameter of system resolution that the ratio of internal and external aperture of vortex ring beam is analyzed,the results show that the resolution produced by narrow band is higher than that of wide band.Second,the annular vortex beam metalens with high transmission efficiency is designed,and a super-atom with polarization conversion efficiency of 98%is obtained to form metalens,then the metalens is carried out by the numerical analysis.Finally,the annular vortex beam and plane wave are focused by the microsphere lens respectively,and the results show that the imaging resolution can be improved dramatically by illuminating with annular vortex beam.(3)The traditional devices of generating Bessel beam have the problems of large volume,difficult integration,spherical aberration affecting the imaging quality and so on.A method of the adjusting light field of imaging plane by plane-axicon for super-resolution microscopic imaging is proposed.Firstly,the super-resolution imaging theory by plane-axicon is studied,and the diffraction limit spot can be reduced by 1/3.Second,a polarization-insensitive planeaxicon is designed based on metasurface.Through the numerical analysis of the plane-axicon,the results show that its FWHM is consistent with the theoretical minimum resolution,and the FWHM shows independent-wavelength property,which is suitable for wide-band optical microscope;in addition,the aberration of the plane-axicon is analyzed.Compared with the traditional axicon,the plane-axicon is a free spherical aberration device,which can improve the imaging quality.Finally,an un-normal plane-axicon is designed by the refraction of the front surface of the substrate,this method can increase the numerical aperture of the planeaxicon and further improve the imaging resolution.(4)The traditional objective lens of the microscopy suffers from the problems that its volume is large and difficult to miniaturize,the designed two kinds of the achromatic metalenses can break through the chromatic aberration problem in the continuous range with large bandwidth,and they would regulate the chromatic aberration of the light field of the objective lens.Firstly,the chromatic aberration theory of the metalens is studied.Second,a wide band achromatic metalenses with one-dimensional and two-dimensional structures are designed through the phase compensation.Finally,through numerical analysis,the FWHM of two-dimensional achromatic metalens is close to the diffraction limit,which is comparable to the existing achromatic lens groups.Notably,the structures of two achromatic metalenses are composed of single-layer nanostructures on the substrate without spatial recombination or cascade,which is significant for replacing the lens group correcting the chromatic aberration in the traditional objective to form a miniaturized objective lens. |
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