Preparation Of Micro-lens Array And Its Experimental Research Based On Microfluid Pulse Jetting

Micro-lens and micro-lens array have important application value and broad prospects in numerous engineering applications as well as the national defense fields.However,the actual fabrication level of the micro-lens array still lags behind the theory design level,and the manufacture of the micro-lens array has become the first problem which needs to be solved for the development and application of the micro-lens array.Most of existing preparation techniques of micro-lens array require multiple process steps that are quite complex and sophisticated,making the fabrication quite expensive.Therefore,the fabrication technology of the micro-lens array which is high efficiency,low cost,and low power consumption has been a hot issue of concern.Aiming at the preparation technology of micro-lens array,in this paper,the preparation of planar micro-lens array,high numerical aperture micro-lens array,and curved micro-lens array based on the microfluid pulse jetting technology is systematically studied and the performance of the prepared micro-lens arrays is evaluated.In this paper,based on pulse driving and controlling of microfluid,the formation princinple of microfluid pulse jetting was analyzed.The formation processes of main and satellite droplets were simulated using computational fluid dynamics method based on the calculating results.The influences of the micro-jetting system parameters and the micro-jetting liquid property on the diameter of the micro-jetting droplet and the micro-jetting formation were studied.The main and satellite droplets forming processes were observed by a home-made stroboscope.These supplied a theoretical basis for the formation of microfluid pulse jetting.The influence of micro-jetting system parameters on the stability and ejection droplet volume of microfluid pulse jetting was experimentally studied.Result showed that,the stable droplet micro-jetting and the micro-jetting droplet volume could be controlled by adjusting the system parameters,and this supplied an experiment basis for the stable and controlled droplet micro-jetting.The wettability and the impact process between the micro-droplet and substrate were theoretically studied,and these supplied.a theoretical basis for deposition modeling of the droplet on different substrates.A novel method for the preparation of ultrahigh F number circular and columnar micro-lens array and multi-scale planar micro-lens array was proposed respectively based on the microfluid pulse jetting technology.The ultraviolet curable(UV-curable)glue was firstly drop-on-demand micro-jetted on the substrate which was special treated,then the micro-lens array was formed after the liquid glue was cured by the ultraviolet light.The micro-lens which the F number is 11.5 and the micro-lenses which the diameter and contact angle can be controlled within a certain range were prepared.The performance measurement results of the prepared micro-lenses and microlens arrays showed that,the prepared micro-lens had good surface profile and surface roughness;The prepared micro-lens with ultrahigh F number can achieve diffraction limit imaging theoretically;and the prepared micro-lens arrays had good imaging and focusing effect.The ultrahigh F number and multi-scale micro-lens array can be fabricated simply and quickly based on the micro fluid pulse jetting.A novel method for the preparation of hemisphere micro-lens,super hemisphere micro-lens with high numerical aperture was proposed based on the microfluid pulse jetting technology and a liquid molding process.The glycerol aqueous solution was drop-on-demand micro-jetted on the hydrophobic surface or super-hydrophobic surface,and the glycerol micro-droplet was acted as positive mold,then a replication process was followed to fabricate the micro-lens with high numerical aperture.The hemisphere micro-lens which the numerical aperture was 0.68 and the super hemisphere micro-lenses which the contact angle could be controlled from 120° to 150° were prepared.Theoretical and experimental analysis results show that,the ultrahigh adhesion force between the glycerol micro-ball droplet and the substrate is ascribed to the Wenzel state of the micro-ball droplet,while the replication process with low position error is attributed to the ultrahigh adhesion force between the glycerol micro-ball droplet and the substrate.The performance analysis and measurement results of the prepared high numerical aperture micro-lens showed that,the prepared high numerical aperture micro-lens had good surface morphology,and the experiment results of multiple imaging and focal length of the high numerical aperture micro-lens arrays were well coincident with theoretical analysis results.During the process of the preparation of the high numberical aperture micro-lens array based on microfluid pulse jetting and liquid molding,the glycerin micro-droplet with a large contact angle on the super-hydrophobic surface can form easier than the UV glue and other polymer,the glycerin was low cost,and good chemical inertness,and the whole preparation process can be completed without in yellow light room.A novel method for the preparation of curved micro-lens array was proposed based on the microfluid pulse jetting technology and a molding process.The planar micro-lens array fabricated based on the microfluid pulse jetting technology was as the positive mold,then the curved micro-lens array was fabricated by multiple molding and soft lithography processes.The deformation of the curved micro-lens during the replication process was analyzed and the result showed that the maximum deformation rate of the curved micro-lens array was within 10%,and the curved micro-lens array still kept good surface roughness during the replication process.The experiment results of multiple imaging and focusing of the curved micro-lens array showed that each micro-lens unit had good imaging and focusing effect,and the field of view angle of the curved MLA,whose radii of curvature of the spherical surface were approximately 1.8 and 5.1 mm,were 140° and 120°,respectively.The fabrication process of the planar micro-lens array which acts as the positive mold of the curved micro-lens array is simple,quick,and direct molding,and the deformation rate of the curved micro-lens during the replication process is small.