Silicon wafers with micro patterns were evaluated as one of the promising molds to fabricate microlens arrays for its high hardness. This study presents an efficient yet flexible manufacturing method for microlens array silicon mold by a polishing method. Unlike conventional processes for microstructures on silicon wafers such as diamond machining and photolithography, this research demonstrates a low-cost and high efficient chemical mechanical polishing (CMP) process with steel balls and diamond slurries for precision microlenses manufacturing. During the CMP process, polishing parameters for each micro cavity need to be accurately calculated and controlled to obtain microlenses with specific apertures. Therefore, a micro wear model for micro cavity CMP process was established to calculate cavity sag height with the knowledge of down force, polishing time and relative velocity between ball and silicon wafer. Several groups of microlenses polishing were then conducted under the same conditions to validate the micro wear model. Guided by the micro wear model, a 5×5 microlens array was fabricated on silicon surfaces. The shape accuracy and surface texture of the microlens arrays were evaluated by using a white light interferometer. This research demonstrates an alternative lowcost and efficient method for microstructure fabrication on silicon wafers and possible follow up optical molding processes.
With the booming of the curved glass shell and curved panel on the smart phone, the development of 3D curved glass molding process, mold and equipment are fairly promoted. This paper introduces a self-developed full-motor-driving precision molding machine’s developing course. Seven different molding stations using electric actuators as molding axes devices are designed in molding chamber to gives good production efficiency and adaptation of complex process to the molding machine. The maximum molding force and the highest molding temperature is up to 5000N and 800oC, respectively, which satisfies different production requirements. The control unit is built based on the industrial computer in the console and consists of two parts: numerical control system and temperature control system. The control unit can control the molding speed, depth, time directly while the molding force and temperature are controlled by the mean of feedback system. A 3D curved glass molding experiment is carried out by using the machine and graphite mold and finally the 3D curved glass is produced. This result shows that the precision molding machine has achieved the designed functions to manufacture the 3D curved glass and other different complex optical components.
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