| The additional value of optical industry is developing from macro optics to micro one.The industrialization urgently needs a rapid and accurate forming technology for the optic products.However,it is difficult to synergize the efficiency and accuracy of traditional hot embossing technology,and it faces the bottleneck of precision manufacturing technology of micro-structural forming core.Therefore,a non-isothermal hot-embossing micro-forming method was proposed by hot-melting a micro-scale polymer surface,and its theoretical model was established to study the rapid and precise hot embossing process.Finally,through the micro-optical design and experimental analysis,the micro-optical characteristics and industrial value of non-isothermal hot embossing microprism and composite microlens arrays are explored.Grinding core micro-structure easily produce edge burrs,so the laser-assisted micro-grinding method was studied,and the transient temperature model of micro-chips synergized by laser energy density and processing parameters was constructed.The effects of laser focusing position,grinding wheel binder,workpiece material and laser energy density on laser-assisted micro-grinding surface roughness and deburring were investigated.The theoretical and experimental results show that the hard alloy core surface roughness R_a can reach 35 nm with the laser fluence of 0.3~0.6 J/cm~2 focusing on the cutting chip.It can not only remove the burr on the edge of micro-structure,but also sharpen the diamond wheel micro-tip.The micro-grinding of smooth structure can be realized without cutting fluid by controlling the instantaneous temperature to fuse chip but not to ablate workpiece.Based on the rheological and stress-strain characteristics of polymer during non-isothermal process,the non-isothermal hot-embossing theory model was constructed by a hybrid of mechanical compression and hot-melt flowing.The effect mechanism of the core micro-structure parameters and hot embossing process parameters on the micro-forming accuracy and efficiency was explored.It is found that the precision of micro-forming can be improved by reducing the angle of core micro-structure and increasing the hot-pressure,and the precise hot embossing of micro-prism arrays can be realized in 1-3 seconds.Moreover, when the surface roughness of the core is less than 90 nm,the microprisms with surface roughness of 20-30 nm can be formed near the glass transition temperature.When applied to LED lighting,it can effectively reduce the total reflection of the light exit surface,and increase the illumination by 26%and the uniformity by 40%compared with the market micro-circular array light guide plate.Based on the non-isothermal hot embossing micro-forming technology,the hot embossing method of composite micro-lens array was proposed,the small micro-lens array was extruded on the surface of the micro-prism with the assist of the elastic micro-porous mesh layer.According to the tension and deformation of microporous mesh,the effect mechanism of line diameter of elastic microporous mesh and hot embossing process parameters on the forming height of microprism,top and platform microlenses of composite microlenses was discussed.The results show that the rapid forming of composite microlens arrays can be realized by controlling the angle of core microstructures,the line diameter of elastic microporous mesh and its tension.The microprism height can reach 80μm,and the the aspect ratio of surface small microlens can reach 0.7.The experimental results show that the composite microlens light guide plate can improve the diffuse reflection and eliminate the mirror reflection of visible light,which is beneficial to reduce the harm of blue light and dazzling light to human eyes.Compared with the microprism array and the market micro-circular array light guide plate,the illumination of the composite microlens light guide plate can be increased by 45%and 83%,respectively. |
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