Design,Fabrication And Application Of Microlens Group Arrays

Microlens array is an array of tiny lens elements with basic functions of focusing and imaging.It boasts a wide range of applications in fields like three-dimensional(3D)imaging,moire imaging,conpound eyes imaging system,fingerprint recognition,and optical communication.Up until now,methods of making microlens mainly include photoresist thermal reflow,two-photon polymerization 3D direct writing,polymer microreplication,electric field driving,ultra-precision turning,reactive ion etching,etc.With the development of microlens technology,the microlens group arrays that can achieve more functions are increasingly favored by researchers.Based on the micro-nano processing-technology,two kinds of microlens group arrays,flat microlens array and biconvex microlens array,were fabricated by using two UV adhesive with different refractive index in this study.And the microlens group arrays were applied to moire imaging successfully.Details are listed as following:(1)The flat microlens array was fabricated by using the well-known technique of modeling-nanoimprinting-leveling-up with the help of photoresist thermal reflow.Its"small numerical aperture" and invisibility helped to solve the existing problems of moire imaging in millmeter-level low pixel,replicability,and lowered imaging after abrasion.The anti-counterfeiting device with new visual characteristics was also made by using the flat microlens moire device to cover the static pattern.(ii)A biconvex microlens array with two refractive surfaces was made with the method of high precision alignment UV imprinting.Its focal length is much larger than the numerical aperture of the eonventional microlens with Then the moird imaging was realized by using this array,and the influence of UV imprinting alignment error on moir6 imaging was also explored.A microlens array with two focal planes was prepared and a moire image of two effects was realized on the same moire device.The preparation methods of the microlens group arrays applied in this study are mainly based on lithography and UV imprint technology,which is easy to operate,low in cost,and applicable to large-scale commercial applications.