像散式讀取頭角度量測性能之精密檢測系統之研發

Abstract

像散式原子力顯微鏡運用DVD讀取頭的高解析線性量測性能以及緊緻和精準的光路結構大幅提昇顯微鏡的調校和量測性能，同時也使原子力顯微鏡的經濟性有級數的提昇。根據光路的分析探討和實驗驗證，DVD讀取頭不只具有線性量測功能更具有角度量測功能，可以偵測被測面角度的變化。線性量測和角度量測性能的搭配可以增加DVD讀取頭在輪廓量測上的功能和性能，並有助於新型原子力顯微鏡技術之開發。本論文研究目標為研發一套精密檢測系統來探討DVD讀取頭之角度量測性能。 精密檢測系統主要由一個精密角度產生機構組成，必須具備高解析和精確度，尖端軸承和刃狀軸承是符合角度產生性能之首選，角度量測訊號之校正也要回溯到長度標準。為了要重複檢測角度量測器之性能，檢測系統也具備自助化檢測的功能，由精密步進馬達和壓電致動器提供重複角度變化，並擷取角度量測器所產生之量測訊號，檢測控制參數和程序之設定以及角度量測訊號之展現都是在個人電腦所建構的量測平台上完成。 常用DVD讀取頭除具有線性位移量測功能也具備角度量測功能，但兩個量測功能具有耦合相互干擾的效果。為了消除這種耦合現象，特別請工研院光電所(ITRI)設計開發了一個新型DVD讀取頭，簡稱ITRI讀取頭，透過改善光斑和光路的方式達成。在角度量測性能檢測上，將分別針對常用DVD讀取頭和ITRI讀取頭，進行光路光斑之分析和實驗檢測。

Through the high resolution measurement function and the compact precision structure of the DVD pick-up head, the astigmatic atomic force microscopy (Astigmatic AFM) has substantially simplified its adjustment operation and significantly improved its measurement performance. Besides, the generally available DVD pick-up head makes the whole AFM system more economical. According to our optical analytical and experimental results, the DVD pick-up head possesses not only the translational measurement function but also the angular measurement function, which can be used to detect the angular displacement of a measured surface. The combination of the translational and angular measurement functions can increase profile measurement capability of DVD pick-up head and also enhance development of new AFM technology. The research aim of this thesis is to develop a precision testing system for validating the angular measurement performance of the astigmatic pick-up heads. The precision testing system is mainly comprised of a precision tilting mechanism, which can precisely drive a high-reflective Si-wafer made mirror to produce accurate and high resolution angular displacement. And the high-reflective mirror is supported by two spike bearings or two knife bearings to realize frictionless rolling bearing contacts. Furthermore its created tilting angle must be calibrated by precision length standard. In order to repeatedly verify the angular measurement performance, the precision testing system is equipped with precision step motor and piezoelectric actuator to create coarse and fine tilting movements. Simultaneously the signal acquisition of the DVD pick-up head is implemented, and a processing platform built in the computer carries out thus testing process, signal processing, and data presentation functions. Besides the common DVD pick-up head, an ITIR pick-up head is especially developed by improving the optical path in order to achieve symmetrical laser spot. The ITIR pick-up head is realized to solve the coupling problem between the focus error signal and the angular signal measured by the DVD pickup head. For validating the angular measurement performances of the DVD and ITIR pick-up heads, optical analysis, error analysis and diverse experimental testings are accomplished.