| Summary: | 碩士 === 國立中興大學 === 精密工程研究所 === 92 === This dissertation describes a key factor to design and fabricate microlens array using hot intrusion technique. During hot intruding, polymers was compressed with temperatures exceeding the glass transition temperature (Tg) and taken off after cooling. Because the non- uniform pressure distributions and the temperature change during hot intruding and cooling, respectively, the final products will display non-uniform shrinkage. Therefore, uniform shrinkage was required for hot intruding procedures. This study thus designed a better intruding process control consisting of the following three stages. 1.Apply larger load during the embossing stage to improve replication. 2.Apply smaller load during the initial cooling stage, while the temperature still exceeds Tg, to minimize pressure variation and thus volume change variation. 3.Increase the holding load in the final cooling stage, when the temperature drops below Tg, to reduce the pressure variation and increase overall shrinkage uniformity.
A 3mm thick PC (Polycarbonate) film is used as the raw material and hot intrusion with Ni-Co mold inserts that made by a single-layer LIGA process. High-aspect-ratio circular holes of 80μm in diameter are designed to form the plastic microlens. The plastic material is intruded into the circular holes and stopped at desired distance by adjusting the embossed load, temperature and time.
The optical properties of these microlenses have been characterized by measuring their focal lengths. The radius of curvature is 196.3μm∼428μm and the heights is 1.87μm∼3.93μm.
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