單晶鑽石銑削雙面陣列鏡頭之研究

近年來隨著智慧型手機的普及、通訊軟體的蓬勃發展，人們習慣於透過手機拍照來分享並紀錄至社群網路，手機的拍照功能儼然成為大眾生活中不可或缺的一部份，鏡頭鏡片的製程技術便成為一道相當重要的課題。隨著科技技術的精進，手機拍攝的照片品質要求則越來越高，然而，現今市面上的手機鏡頭多為縱向疊加多片鏡片組合而成的單顆鏡頭，雖然拍攝出來的照片擁有高解析度，但是卻會產生景深問題而導致對焦區域以外的成像模糊，因此如何克服景深問題成為一重要課題。陣列鏡頭是藉由不同非球面排列而成，可同時記錄著多點影像景深資訊，並擷取多焦距成像之影像，經過後處理程序轉換成清晰且無景深之照片。不同於傳統式變焦透鏡，以多層鏡片疊加的硬體機構，陣列鏡頭的設計帶來了更簡單、更輕薄等特性；由於陣列鏡頭不具備調焦的功能，因此每顆鏡頭需有較好的尺寸及形狀精度，且其透鏡需有較理想的折射性和聚焦性。本實驗目的為探討3x3陣列鏡頭的加工製程，藉由NanoCAM 3D軟體建立非球面曲面，並對曲面進行分析以及路徑規劃，進而找出適當之刀具規格。此外本實驗為直接在鏡片的兩面加工陣列非球面透鏡，設計對位機制，減少雙面加工時的定位誤差，提升鏡頭的成像品質。最後使用超精密加工機搭配軟體分析之單晶鑽石球銑刀規格銑削3x3之陣列鏡頭，並使各個非球面之形狀精度達到0.8 µm PV以下，以符合鏡頭光學設計時之要求。

關鍵字

非球面透鏡；陣列鏡頭；超精密加工；單晶鑽石銑削；形狀精度

並列摘要

In recently years, smart phones and social media have become more and more popular. People are now used to take photos with mobile phones and share them via social network. Mobile phone camera is now an inseparable part of people's daily life. Since the reliance of such device has increased, lens machining for mobile phones has become one of the most important issues in manufacturing technology. As smart phone technology advances day after day, photo quality requirement increases accordingly. However, most of the available phone cameras use single lens structure, which consists of multiple optical lens stacking parallelly. The design gives photo with high resolution, but limited depth of field (DOF) causes unfocused area in the image. With different aspheric lens in array, the camera can record specific DOF information from different points, and capture images of multiple focuses. Post-process then turns the captured images into a single clear photo without DOF. Unlike conventional mechanical zoom lens, lens array features simplicity and lightweight. Incapability of changing focal length indicates each lens in lens array needs better refractive and focus ability, which leads to higher form accuracy requirement. The purpose of this work is to study the manufacturing process of 3x3 lens array. Asphere building surfaces using NanoCAM 3D, surfaces analysis and tool path planning are featured in this work. Proper tool specification will also be tested to optimize the process. Additionally, the experiments are performed by directly machine aspheric surface on both sides of the lens. In order to reduce location error in two-side machining and improve image quality, alignment mechanism is designed in this work. The lens array of 3x3 is machined by ultra-precision milling machine, using analyzed single-crystal diamond tool. Measurement results shows that the form error of each aspheric lens is less than 0.8 µm PV, meeting optical design requirement.

並列關鍵字

aspheric lens ； lens array ； ultra-precision machining ； single-crystal diamond milling ； form accuracy

參考文獻

[1]N. Taniguchi, "Current status in, and future trends of, ultraprecision machining and ultrafine materials processing," Annals of the CIRP, vol. 32, pp. 573-582, 1983.