UV固化壓印製程應用於雙面非球面微透鏡陣列製作

Abstract

本研究以UV固化壓印之方法製作雙面非球面微透鏡陣列(5×5)。首先製造非球面微透鏡陣列鋁模具，利用鋁模具為母模，翻製透明PDMS模仁；同時設計加工有對位機制的PMMA模座，將PDMS模仁鑲嵌於有對位機制的PMMA模座。模具置於合模對位機台上，搭配即時光學對位系統，完成UV固化壓印機台。接著進行紫外光固化製程，於四吋圓上製作雙面非球面微透鏡陣列，控制合模速度在0.7 mm/s以下時，成品無殘留氣泡；凸透鏡高度複製率達98.58%，凹透鏡高度複製率達98.26%，微透鏡陣列均勻性其直徑變異係數0.31%，高度變異係數0.41%，結果顯示本製程能完整製作四吋圓雙面非球面微透鏡陣列。 本研究進一步量測雙面非球面微透鏡陣列之光學性質，分別量測觀察雙面非球面微透鏡陣列之有效焦距、光斑直徑與光學成像。平均有效焦長為1.433 mm，變異係數0.0065%，表示成品之成型性非常均勻。將原光源為1.2 mm直徑大小縮至僅剩45 m之光斑直徑大小，表示此雙面非球面微透鏡陣列擁有聚焦性質，而英文字母圖案G經由聚焦後其成像完整清晰，本研究證明以UV固化製作雙面非球面微透鏡陣列的可行性。

In this research, UV curing imprint process is developed to fabricate a 4-inch double sided aspheric microlens array (5×5). Aluminum mold for aspheric microlens was first manufactured. Transparent PDMS mold core was replicated using the aluminum mold as the master. The PDMS mold cores were embedded in the PMMA mold base which was designed with alignment mark. A compressing machine customized for UV curing process with real-time optical alignment system was implemented for UV curing imprintng. After the UV-curable resin was coated on the cavity, the molds were slowly clamped and the cavity was filled. After the resin was cured with UV light, aspheric microlens array with convex profile on one side and concave profile on the other side was fabricated, the cycle time is 110 s. For the convex profile, the degree of replication was 98.58%, and 98.26% on the concave profile. As far as uniformity is concerned the coefficient of variation of diameter is 0.31%, while the coefficient of variation of height is 0.41%. The optical properties of the double-sided aspherical microlens were measured. The original light source of 1.2 mm diameter is reduced to 45 m as the spot diameter. The average effective focal length 1.433 mm and its coefficient of variation is 0.0065%, indicating the formability and uniformity. The G patterns is present a complete and clear optical image. This study demonstrates the potential of UV curing imprinting for forming double-sided aspheric microlens arrays for optical application.