Development Of A Miniaturized Wavefront Microscopy Imaging System

Different from the classical common bright-field and fluorescence microscopy imaging,Quantitative Phase Imaging(QPI)technology can not only obtain high-contrast images of label-free samples but also accurately reconstruct the optical thickness of the object,which provides an important imaging tool for the life science field,thus gaining widespread attention.A series of quantitative phase imaging devices have been developed based on quantitative phase imaging technology,including digital holographic microscopy system and spatial light interference microscopy system,as well as Shack-Hartmann wavefront sensors,quadriwave lateral shearing interferometry and transport of intensity phase imaging devices which can be directly integrated with the microscopy imaging system.These systems and devices have been successfully applied in various fields such as cell observation,tissue imaging,and micro-nano structure measurement,and have obtained high-quality measurement and imaging results.However,these systems and devices still rely on the large size and high-cost microscopy imaging system,so there is still lacking a wavefront imaging microscopy with good imaging effect,compact size,controllable cost,and other advantages.In order to solve the above problem,this paper presents a dual-view real-time wavefront imaging method based on the transport of intensity phase imaging technology,which overcomes the difficulty of real-time dynamic imaging with the transport of intensity phase imaging.On this basis,we designed a miniaturized wavefront microscopy imaging system,which is called Phase station.The key idea of the Phase station is real-time capture and correct multi-focal-plane images of the field of view to be measured,the quantitative intensity and phase distribution of the field are reconstructed by solving the Poisson equation,thus realizing the quantitative wavefront microscopy imaging.Combining partially coherent light source module,concentrator module,objective lens,sample stage,and multi-focal-plane real-time imaging module,the prototype of miniaturized wavefront microscopy imaging system is built in this work.When using a 10× objective lens and a CMOS imaging sensor with the pixel size of 4.8 μm and pixel number of 1024 × 1280,the spatial resolution of Phase station can reach 2.19 μm.In addition,the standard sample is used to prove that the system has better phase reconstruction accuracy.Therefore,this prototype not only has high quality imaging effect but also has the compact system and controllable cost.However,due to the limitation of the space-bandwidth product of the microscope objectives,the prototype of the miniaturized wavefront microscopy imaging system in this paper still has the defect of limited measurement field of view,which makes it difficult to realize the measurement of large-scale and large flux samples.In order to put the Phase Station into use,this paper also combined mechanical scanning based on a sample translation platform and microfluidic sample scanning based on a microflow channel to carry out the application research of whole slide digital wavefront imaging and flow cytometry phase imaging.In order to realize digital wavefront imaging of large-size and label-free samples,based on the miniaturized wavefront microscopy imaging system,a 3D precision translation platform is added to scan the samples to extend the field-of-view.The core idea is that the miniaturized wavefront microscopy imaging system can record the images of under-focus and over-focus intensity in real-time when the samples are scanned by a 3D precision translation platform.Combined with field-of-view stitching and correction,extended field-of-view under-focus and over-focus images can be obtained.Finally,the wavefront(intensity and phase)distribution of the full-field of view of the sample was reconstructed by solving the Poisson equation,that is,the whole slide digital wavefront image was finally obtained.Use of label-free blood smear and cross-cut pumpkin stems as samples,the phase station acquires a whole slide digital wavefront image of a 3 mm × 3 mm region in 2 minutes.As a prototype of whole slide digital wavefront imaging equipment,the miniaturized wavefront microscopy imaging system designed and constructed in this paper can provide a new tool for digital pathology.In order to realize fast scanning,imaging,and detection of samples,a microfluidic system is introduced in this work on the basis of the miniaturized wavefront microscopy imaging system which has been constructed to realize fast scanning of tested cells.The core idea is to import the sample into the microfluidic chip and realize the rapid flow of the measured cell sample in the microflow channel through the injection pump.Combined with the real-time wavefront measurement capability of the miniaturized wavefront microscopic imaging system,the phase of the cell sample can be rapidly measured,the characteristics of the cell sample can be reconstructed,and the cell count,analysis,and measurement can be realized.Using Sodium-calcium glass standard microspheres and red blood cells as samples,the miniaturized wavefront microscopy imaging system for flow cytometry phase imaging can achieve high-quality cell imaging and high precision measurement at flow rates of 10 μL/min,providing new techniques and methods for rapid cell detection.In summary,the development of miniaturized wavefront microscopy imaging system based on the transport of intensity phase imaging technology and its exploration in whole slide digital wavefront imaging and flow cytometry phase imaging have expanded the application range of quantitative phase imaging technology and provided a new idea for the development of miniaturized portable quantitative phase imaging system.