- 學位論文
採回授控制之抗振式白光干涉量測系統之研發
Development of a Vibration-Resistance White Light Interferometric System Employing Feedback Control
摘要
本論文在發展一套白光干涉回授抗振儀，結合面外位移光學偵測技術與回授補償來控制壓電位移轉換器進行振動補償。白光干涉量測技術具有量測微奈米級檢測能力與大範圍量測之特性，但相當容易受到環境振動而影響到其量測精度。本系統是藉由結合接近單一波段與可見波段光源之雙光源架構，並搭配雙相機同步取像方式，來達到振動偵測的能力，並以白光干涉垂直掃描為基礎，建構在Mirau干涉儀架構上。本系統藉由雙光源以共光路方式進入白光干涉顯微儀中，當兩道光經過分光鏡後，單一波段光源會產生高同調訊號，而可見波段之光源為低同調訊號，故高同調訊號與低同調訊號可由線型高速相機與面型高速相機分別進行擷取。此時利用線型高速相機具有高時間解析能力，發展時間相位移偵測技術，可獲得環境振動之即時位移資訊。利用所偵測到的位移變化，來控制壓電位移轉換器進行振動位移之補償，達到抑制振動之功效，完成垂直掃描後即可利用白光干涉演算法來取得待測物之精確三維形貌重建結果。本研究所發展的相移偵測技術可使偵測振動速度達到64 μm/s，符合靈敏設備振動標準VC-A規格，與校正機台SIOS雷射干涉測距儀相比，平均位移差異在30.1 nm以下，主動式補償有效抗振頻寬為 128 nm/s，平均誤差為6.5 nm，驗證本方法可達奈米級之位移量測與補償能力。
並列摘要
This thesis presents a new white-light interferometry having vibration resistance capability by developing in-situ optical detection and close-looped feedback using a piezoelectric translator. White light interferometry has become a common tool for measuring micro surface profiles having a large height range with a nano-scale resolution. However, similar to other interferometry measurement techniques, it is easily influenced by environmental vibration or noisy disturbance. Environmental disturbance affects in-situ micro surface profilometry by varying the distance between a detected object and Mirau interferometric objective. To resolve this issue, a novel optical system was developed to detect vibratory displacement for real-time fringe locking. A specially designed light source which combines white light with infra-red light is employed to achieve high-coherent and low-coherent interferometry simultaneously. The high-coherent interferometric light is captured by a high speed camera for detecting environmental vibration and the vibratory displacement is compensated by the developed DSP-based fringe-locking algorithm. From the experimental test results, the response bandwidth of the developed phase shifting detection method can be up to 64 μm/s. The detected method was compared with a calibrated SISO laser interferometer system and was confirmed that the measured averaged deviation was less than 30.1 nm maximally. The external vibration speed that can be compensated by the system can be up to 128 nm/ s with an averages measured error less than 6.5 nm.