| 摘要: | 光學及光電產品對於光學元件設計的需求不在僅是一般的球面，對於非球面及自由曲面(非軸對稱)形狀的需求與日遽增，除了形狀的複雜度增加之外，對於其形狀精度的需求也不斷提高，而微透鏡陣列即是一般常見需求量大且不易生產的光學元件之一。微透鏡陣列被廣泛的應用於各式光學元件中，如晶圓級光學、照明光學系統、光纖耦合器、液晶顯示器的增效模組、微型投影機及掃描器CIS模組中的透鏡等。
目前已經成功地被開發出來的微透鏡陣列製程，如熱熔法、各式能量束加工法、超精密加工、材料疏水性應用、LIGA/類LIGA及熱壓成型等製程。在各式各樣的製程中，超精密加工法能達到較高的形狀精度及較好的表面粗糙度，且能於材料的種類及形狀的設計中提供最大的選擇彈性。
目前超精密加工以快刀伺服、慢刀伺服及微鑽石銑削三種方法最常被用來製作微透鏡陣列。儘管慢刀伺服輔助加工具有不需額外的裝置及加工設定容易的有點，但其複雜的三維刀具補償及刀具路徑規劃往往會導致形狀精度不佳、刀具壽命不佳及粗糙的表面粗糙度，本研究的主要目的為建立慢刀伺服輔助鑽石車削的三維的刀具形狀補償模型來加工晶圓級光學所需對稱排列的微透鏡陣列。
本研究成功地加工出形狀精度(P-V)及表面粗糙度(Ra)分別小於0.2μm及5nm具有非球面的百分之一百填充率的微透鏡陣列，其每顆微透鏡形狀精度的均勻度小於0.05μm。除了車削的探討外，一維及二維的慢刀伺服輔助鉋削加工也同樣地被探討於本研究中，於掃描器所使用的微透鏡陣列其形狀精度小於0.2μm、表面粗糙度低於5nm、每顆微透鏡的均勻度小於0.05μm及矢高誤差小於2μm，藉由刀具路徑產生的演算機制及二維的慢刀伺服輔助鑽石鉋削所加工出來。
Owing to the demand from fast growing optical and opto-electronic industry, optical design has advanced from merely planar/spherical to aspheric and to free-form (non-axial symmetrical) in shapes. On top of the increasing complexity in shape, the requirement for form accuracy is getting higher. Micro-lens array (MLA) is one of the typical examples of these difficult-to-produce optical components which are in great demand. MLA has now been widely used in wafer level optics, lighting system, optical fiber coupling devices, brightness enhancement system of LCD, pico-projector, lens of CIS module scanner and etc. Several processes, namely, thermal reflow process, energy beam processing, ultra-precision machining, LIGA/LIGA-like, have been successfully developed to fabricate MLAs. Amongst those processes, ultra-precision machining is considered to be able to achieve higher form accuracy, better surface roughness, and to offer greater flexibility in material/shape selection.
Three ultra-precision machining processes namely fast tool servo, slow tool servo and diamond milling, are frequently used to produce MLA. Though slow tool servo has the advantages of no extra attachment and fast setting-up, the complicated three dimensional tool shape compensation and tool-path generation are major reasons for resulting in poor form accuracy, pre-matured tool failure and terrible surface finish. This research aimed to develop a model of three dimensional tool shape compensation for generating 3D tool path in slow tool servo diamond turning of symmetrically arranged MLAs such as those in wafer level optics.
An aspheric MLA of 100% filling factor with form accuracy (p-v) and surface roughness (Ra) better than 0.2 μm and 5nm respectively was successfully produced in the present study. The uniformity of each micro lens was less than 0.05μm. Apart from turning tests, 1D/2D slow tool servo diamond shaping tests were also investigated in this research. The MLA of scanner with form accuracy of 0.2 μm, Ra of 5nm, uniformity of each micro lens ≤ 0.05 μm and sagittal error ≤ 2 μm was generated by the developed tool generation algorithm and 2D slow tool servo diamond shaping process. |
