像散式光學偵測系統：奈米量測新利器

Astigmatic Detection System: New Tool for Precision Measurements

像散式偵測已被廣泛應用在光碟機產業，用來判斷光碟片與光學讀取頭的離焦情況。中央研究院物理研究所與台灣大學機械系的團隊發現，DVD光學讀取頭可以達到次原子級的位移解析度及奈米弧度級的表面傾角變化的精密量測。除此，光學讀取頭的偵測光點小於1微米，偵測頻率達60 MHz以上，可偵測很小元件的高頻運動，加上光學讀取頭取得容易、且價格低廉，所以能夠發展出很多不同的應用，包括科學教育的教具及訓練工具，甚至研究級的精密儀器設備。本文將介紹光學偵測系統的原理、技術的發展、在奈米級量測的應用、以及本團隊所開發的各種獨步全球的技術，也期望能結合更多學界與業界有志之士，一同推廣像散式光學偵測的量測技術，讓台灣在奈米精密量測能在國際上扮演重要角色，甚至讓台灣的精密量測產業更往前邁進一大步。 Astigmatic detection was originally developed in the optical disk recording technologies to detect the defocused condition of the disk away from the optical pickup head. Our team, comprising a group in the institute of Physics, Academia Sinica and a group in the Department of Mechanical Engineering of National Taiwan University, has discovered that the commercial DVD optical pickup head has a sensitivity to detect linear displacements of sub-angstrom scale and angular changes in nrad. In addition, the detection spot size is smaller than 1 m m and the detection bandwidth is higher than 60 MHz, thus the DVD optical pickup head can detect high-frequency movements of small objects. Furthermore, it can be purchased easily with a low cost. This opens up various applications from low-cost education and training tools to sophisticated research instruments or equipments. In this article, we will describe the principle of astigmatic detection system(ADS) , development and applications of the technology in precision instrumentation, and world-leading ADS technologies developed in our team. We hope to cooperate with other scientists and experts in industry to broaden the application of ADS technologies, and to even bring forth new technologies and industries.