Research On The Law Of Super-resolution Imaging Of High Refractive Index Microspheres And The Reduction Of Imaging Distortion Rate

In the optical lens-based super-resolution imaging technique,the microsphere-assisted optical microscopy method is a new optical super-resolution imaging technique proposed in recent years.This technique has the advantage of using less energy white light as a light source and the sample does not require fluorescent labeling.In addition,microspheres with higher-index have many advantages in immersion method and imaging characteristic.In this context,the super—resolution imaging properties of high-index BaTiO3 glass(BTG)microspheres have been studied in the following aspects:1.The geometrical optics theory and physical optics theory of microsphere imaging were studied.The imaging properties of high refractive index microspheres were analyzed by formula derivation and software simulation.2.The imaging properties of BTG microspheres in the diameter range of 5—50 pm which are fully immersed in a polydimethylsiloxane layer are experimentally studied.Our experimental results show that for both Blu-ray disc samples and the single-layer hexagonally close-packed microsphere array samples,with the increase of the diameter of BTG microspheres,the range of focal image positions(RFIP)increases linearly.When the diameter of BTG microspheres increases from 5 to 50 μm,the RFIP changes from 4 to 25 μm.For the microsphere array samples,Talbot effect is observed,and both the position of Talbot images and the Talbot distance depend on the diameter of BTG microspheres.Numerical simulations indicate that the length of the photonic nanojet changes from 2.9 to 7.1 μm when the BTG microsphere size increases from 5 to 50 μm,and the calculated RFIP is between 6 and 24 μm.The calculated RFIPs match well with the experimental ones.Our researches reveal that the RFIP depends on the length of the photonic nanojet of the BTG microsphere.3.We experimentally demonstrate that the pincushion distortion is obvious when using a BaTi03 glass(BTG)microsphere fully immersed in ethanol or SU-8 2002 resist to image a Blu-ray disk with sub-diffraction features.The distortion is related to the layer thickness of the immersing medium.For a BTG microsphere partially immersed in the SU—8 resist where the SU—8 thickness is around 4/5 the diameter of the microsphere,its distortion will decrease dramatically,but it can still clearly resolve the Blu-ray disk.For such a partially immersed microsphere,the calculated position of the photonic nanojet is outside the microsphere and close to the object,indicating the microsphere has the super－resolution imaging property,and the distortion simulated by ZEMAX is decreased.