Study On Optical Design And Precision Grinding Of Energy-Saving Arc Micro-prism Array

With the crisis of energy and environment,LED lighting achieving environmentprotection and energy-saving has been widely used.Using multiple rows of LEDs,LED lighting could achieve spot-to-surface illumination through uniform micro-dot array and linear microprism array.However,it would lead to high energy consumption.Hence,a new arc micro-prism array is proposed with a single or two LEDs in order to achieve more energy-saving lighting effect.Besides,the micro-optical principle and performance of arc micro-prism array were studied,and the spatial geometric structural parameters of arc micro-prism array were designed.However,there is no surface processing method for arc micro-prism array with integrated shape accuracy and smooth surface.For this reason,the method of overcut micro-grinding with three-axis numerical control and one-axis differential motion was proposed on controlling spatial surface parameters by using high precision micro-tip of diamond wheel.Besides,the overcut micro-grinding using only one process of arc micro-prism array was studied on forming mechanism and precision control.Furthermore,high precision micro-forming metal core was manufactured by the overcut micro-grinding process.In order to achieve rapid and mass production of optical polymer(PMMA),the micro hot-embossing process of LGP was studied.First,the method of overcut micro-grinding with three-axis numerical control and one-axis differential motion was proposed.The parametric model of arc micro-prism structural surface was constructed using the overcut micro-grinding theory.In addition,the arc micro-prism array LGP was manufactured by precision grinding machine.The experimental results showed that the overcut micro-grinding was able to fabricate smooth arc micro-prism array LGP with high aspect ratio.The size error was less than 0.5%.The aspect ratio and roughness reached 0.24 and 94 nm,respectively.Applying to optical polymer lighting,the arc micro-prism array reduced the micro-prism number by 73.8%,enhanced the efficiency by 45.5% and uniformity by 15.3% against the linear micro-prism array,respectively.Then,the molded metal core with high hardness was manufactured by the overcut microgrinding process.In order to ensure the accuracy,the mechanism of grinding parameters and tool wear rate was studied.In the condition of manufacturing S136 H die steel with 55 HRC,the size and shape error of arc micro-prism with an angle of 125.2° and a depth of 387.5 μm were less than 0.2% and 1.9%,respectively.The aspect ratio and roughness of arc micro-prism array reached 0.23 and 152 nm,respectively.Finally,the micro-forming die core was applied in micro hot-embossing process to realize rapid and mass production of LGP.The effects of filling rate and roughness on product performance were discussed through experiments.In the condition of hot-embossing temperature 120 °C,forming pressure 12 MPa and holding time 7 s,the efficiency could reach 82.2%.Besides,the arc micro-prism array produced strong ability of heat dissipation due to reducing source temperature by 1.7 °C and the whole LGP temperature by 1.2 °C,respectively.