Abstract
Surface rapid heating process is an efficient and green method for large-volume production of polymer optics by adopting 3D graphene network coated silicon molds with high thermal conductivity. Nevertheless, the heat transfer mechanism including the interface thermal resistance evolution between 3D graphene network coating and polymer has not been thoroughly revealed. In this study, the interface thermal resistance model was established by simplifying the contact situation between the coating and polymethylmethacrylate (PMMA), and then embedding into the finite element method (FEM) model to study the temperature variations of PMMA in surface rapid heating process. Heating experiments for graphene network were then carried out under different currents to provide the initial heat for heat transfer model. In addition, residual stress of the PMMA lens undergoing the non-uniform thermal history during molding was presented by the simulation model together. Finally, the optimal molding parameters including heating time and pressure will be determined according to calculation results of the interface thermal resistance model and microlens array molding experiment was conducted to illustrate that the interface thermal resistance model can predict the temperature of the polymer to achieve a better filling of microlens array with smooth surface and satisfactory optical performance.
Highlights
With the rapid development of high-resolution cameras and lighting systems, polymer optical elements with micro-scale three-dimensional structures have gained growing attention for their novel applications
PMMA, we focused more on its surface adjacent to graphene, so we refined the grids for the wewe focused more on itson surface adjacent to graphene, so we refined the refined grids the grids thePMMA, PMMA, focused more its surface adjacent to graphene, so we that part
The interface thermal resistance evolution between 3D graphene network and polymer has been thoroughly investigated based on Hertz contact theory that the relationship between interface thermal resistance and molding pressure and temperature was achieved
Summary
With the rapid development of high-resolution cameras and lighting systems, polymer optical elements with micro-scale three-dimensional structures have gained growing attention for their novel applications. Due to its control of light reflection, refraction and diffraction, can realize complex imaging, rapid positioning, range and speed measurement, navigation, beam guidance and optical communication in civil and military applications. Given their merits of small volume and mass and high sensitivity, many researchers over the past several decades have contributed huge effort in the fabrication of various microlens array systems. Several approaches have been applied to produce microlens array optical components, such as replication technology (including compression molding, hot embossing [1], injection molding [2,3,4], etc.), liquid lens, thermal reflow, DMD maskless lithography, two-photon polymerization 3D printing, etc. Huang et al [8] combined dose-modulated DMD-based lithography and surface thermal reflow process to achieve high-quality aspheric microlens array fabrication
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