Researchers at SHENZHEN Advanced Institute of Technology generate “wide and thin” optical plates for optical microscopy

2022-06-10 0 By

On March 26,Shenzhen advanced technology, Chinese Academy of Sciences institute of electro-optical engineering technology center keyboard those senior engineer team in a well-known optical journal called Letters on published titled “Quasi – non – diffracting static light sheets generated byAn optimised pupil mask design method for generating thin and wide quasi-diffractive laser masks is reported by holistically optimizing pupil masks.Postdoctoral researcher Cheng Tang is the first author of the paper, and Jianping Li is the corresponding author.Light sheet microscopy is a revolution in biological imaging in vivo.By limiting the excitation laser to the thin layer near the depth of field of the microscopic objective, the defocus blur and photobleaching and phototoxicity of the microscopic imaging can be reduced, which greatly improves the image clarity and prolongation of the observation time of biological samples.Three-dimensional images can be formed by scanning samples or light slices layer by layer.Millions of pixels of planar array digital camera are used for parallel sampling of target faults in focal plane, which has very high sampling speed.High flux flow microscopy imaging can also be realized with flow sampling method.Fluorescence microscopy is an ideal method to characterize living cells, tissues, embryos and organs due to its high definition, nondestructive, three-dimensional and rapid development.However, the imaging performance of film microscopy is limited by the optical properties of the film, its imaging resolution is limited by the thickness of the film, and the imaging field is limited by the width of the film.The thickness and width of the wafer balance each other due to the inherent diffraction properties of the light wave.Thin film supports high resolution, but the diffraction divergence is fast and the effective width is narrow, which limits the imaging field of view.Thick film diffuser diffuser slowly, support the large field of view imaging, but limit the resolution.The diffraction property of light results in a natural contradiction between imaging resolution and field of view, which limits the size and characterization flux of individual organisms in optical microscopic imaging.High resolution large field of view microscopy requires a thin and wide light plate with non-diffraction properties.Non-diffracted light is accompanied by sidelobe, which constitutes defocus background noise for imaging.Therefore, the effect of sidelobe must be controlled for microfluorescence imaging based on non-diffracted light plates.To address this problem, Dr Tang and Dr Jianping Li proposed a numerical optimization method that can be used to design diffractive optical devices called pupil masks to produce thin and wide plates of light.By modulating the amplitude or phase, the diffraction optical device can adjust the thickness, width and side lobe of the light plate, thus breaking through the restriction of gaussian beam propagation law, and realizing thin and wide light plate only by using cheap column lens and mask.In this method, a global quality evaluation factor is cleverly proposed to characterize the balance among the thickness, diffraction free range and sidelobe.Theoretical and experimental results show that the optimized mask can enlarge the non-diffraction range of the static light by 50% while reducing its sidelobe by less than 20%.Thus, the new static film can achieve larger field imaging without sacrificing axial resolution.This work was supported by the China Postdoctoral Science Foundation, the Instrument Project of the Chinese Academy of Sciences and the key project of Shenzhen Science and Technology Innovation Commission.Figure 1: Pupil mask used to generate quasi diffractomless light sheet and its usage Diagram 2: the width and thickness of light sheet measured in the experiment of the phase pupil mask designed and prepared