Optical Superresolution Microscopy Based On Microsphere Characteristics

The invention of an optical microscope has enabled the human science and technology community to achieve a major leap forward.The scientific research before the birth of the microscope mostly stays on the natural surface of humans.The appearance of microscopes has brought people's observational fields into the micro world.Biologists have therefore seen the tiny cellular internal structures that make up animal and plant problems.Medical scientists have seen bacteria and various types of infections in patients' bodies,which has brought convenience to more diseases.In recent decades,the microscope has contributed to people and society in many fields and has become an indispensable tool.With the rapid development of science and technology,people have put forward higher requirements for the resolution of the microscope.Due to the limitation of optical diffraction limits,the lateral resolution of conventional optical microscopes is limited to one-half wavelength,approximately.this can not meet the needs of people for the exploration of the microcosm.In this paper,the super-resolution imaging is studied based on the characteristics of the microsphere lens.Mainly divided into several sections:1.Analysis of super-resolution focusing characteristics of photonic nanojets in microspheres.on the basis of the Mie theory,we calculate the electromagnetic field distributions of the inner and near-field microspheres Under plane-wave incident conditions.When the incident wavelength,the size of the microlens,and the relative refractive index of the microlens are respectively changed,the changes in the electromagnetic distribution inside and near the field are observed.Based on this,the characteristics of the photon nano-focusing effect were analyzed,and the factors affecting the photon nano-focusing effect were discussed in this paper.2.Analyzes the two major theories of geometrical optics and wave optics of microlenses.We get formulas for the magnification,resolution,and focal length of microlenses in geometric optics,combined with the first part of the Mie theory,the focal lengths of different sizes of microlenses are obtained,and compared with the corresponding focal lengths of geometrical optics,the focal length of wave optics is found to be less than the focal length of a geometrical optical microlens.We use the silica microspheres with lower refractive index and suitable size observe the Blu-ray disc with an ordinary upright optical microscope to obtain clear stripes that cannot be distinguished by ordinary microscopes.Based on the Fresnel diffraction,we get a rough calculation of the microlens resolution under wave optics.According to the experimental super-resolution fringe,the corresponding resolution is calculated,and the resolution is better than that of the geometrical optics.3.For microspheres that can achieve higher resolution imaging,extensive reading of literature and finding data,we widely read literature and find information,we think the reason for the discovery of microsphere superresolution imaging is the Fourier transform nature of the lens.In the plane wave incidence,the microlens has a phase change,and when the object plane and image plane satisfies a non-conjugation relationship or sets an appropriate object distance and image distance,the micro lens can achieve fractional Fourier transform.Different transformation orders correspond to different image plane,while plane wave spectra on the image plane compress the corresponding coefficients.From Fourier optics,we know that the spectrum compression and the object magnification.So it gives the magnification range of the lens.It will be better if the specific value of the magnification can be obtained according to the image distance.There is another way to explain that the true mechanism of super-resolution for microlens-assisted microscopy is that after the plane wave passes the lens,the photonic jets become the secondary light source to image the object through the lens.This paper analyzes and calculates the field distribution of the image plane imaging by the photonic jets of the wave optics and imaging by the plane lightof the geometric optical.We can see that the optical imaging of the secondary light source has good focusing effect.