Microscopic Scanning Imaging Of Microsphere Lens Based On Dual Fiber Optical Tweezers

Optical microscopic imaging is the basis for exploring the microscopic world and is widely used in disciplines such as biology,chemistry,medicine and ultra-precision measurement.Conventional optical microscopy has a lateral resolution of 200 nm in the visible wavelength band,which limits further in-depth exploration of the microscopic world.In recent years,researchers have proposed different methods to implement ultramicroscopic imaging techniques to break the diffraction limit.Among them,the use of microsphere lenses to achieve super-resolution microscopic imaging is mainly through the microsphere superlenses to amplify the object surface information and project it into the conventional microscope objective.This technique has significant advantages such as easy implementation,simple and direct,and marker-free,and has great development potential.Thus,an ultramicroscopic imaging processing method based on dual fiber optic tweezers technology is proposed,and an ultramicroscopic imaging system based on microsphere lenses is constructed.The system can realize two imaging modes,both parallel multicellular lens-based ultramicroscopic imaging of disc samples at rest and scanning imaging of disc samples.This study can further expand the field of view of microsphere lenses,optimize the operation steps,and also be applied to different fields to realize non-contact sample imaging with microsphere lenses.1.A theoretical study of the ultramicroscopic imaging mechanism of microsphere lenses is conducted.Firstly,we start from the analysis of electromagnetic field theory,based on Maxwell’s set of equations,and then analyze the influence of the parameters in the timeharmonic electromagnetic field and the fluctuation equations of the spherical coordinate system on the imaging of the microsphere lens,so as to derive the theoretical model of the ultramicroscopic imaging of the microsphere lens.The Mie theory is also introduced to calculate the electromagnetic field distribution in the internal and near-external regions of the microsphere lens.The nano-jet effect of the microsphere lens is investigated by geometrical optics,and the principle of microsphere lens imaging is analyzed,which lays a theoretical foundation for the microsphere lens ultramicroscopic imaging by two-fiber optical tweezers.2.A dual-fiber optical tweezers-based system is proposed to achieve two modes of manipulating microspheres,which can achieve both directional movement and stable quiescence of microspheres.The method achieves manipulation of the particles by varying the light field emitted from the fiber optic probe.During the system design process,three different structures of the fiber tip were compared in simulation experiments,and it was found that the fiber with parabolic-shaped tip has better trapping effect.The parabolic fiber tip was used to capture microspheres to obtain a microsphere lens-assembled fiber probe,which further changed the outgoing light field pattern to obtain a converging beam instead of the normal diverging beam.By simulating the outgoing optical field of the microsphere lens-assembled fiber probe and introducing another fiber with the same structure to form a two-fiber optical tweezer system,stable capture and directional movement of the microsphere is achieved.And the Brownian motion of microspheres in aqueous solution can be overcome when manipulating the microspheres at rest,which makes it more stable when capturing and manipulating the microspheres.In the experiments,the manipulation of polystyrene microspheres in both directional motion and stable stationary mode was achieved by a dual fiber optic optical tweezer system.It has important application value for microsphere lens super-resolution imaging.3.A dual fiber optic optical tweezer system based on a biological cell lens is proposed for achieving ultramicroscopic scanning imaging.This system expands the imaging field of view and avoids damage and contamination of experimental samples during the experiment.Specifically,the method is to introduce the dual fiber optic optical tweezer system to biocell microspheres-based ultramicroscopic imaging.First,microspheres with suitable refractive index and diameter are selected by simulation and experiment.Secondly,Chlorella cells were analytically selected as the bio-cell lens,and a model of the dual fiber optic optical tweezers system for manipulating Chlorella cells for ultramicroscopic imaging was constructed on the premise that Chlorella cells can be imaged and easily captured by the fiber optic tip.Finally,the assembled biolens dual fiber optical tweezers system was used to observe the object to be measured,and parallel multicellular imaging and real-time scanning imaging of disc-striped samples were realized.The system can well solve the problems of position fixation and imaging field of view during microsphere lens ultramicroscopic imaging and simplify the experimental steps.This bio-based low-damage,real-time,arbitrary-area,non-contact imaging system has promising applications.