以光學讀取頭系統實現之輕敲式原子力顯微鏡

本論文研究之目的是設計並實現一輕敲式原子力顯微鏡 (tapping-mode atomic force microscope)，其中使用光學讀取頭作為探針在垂直方向上的位移量測系統。此光學讀取頭系統取代傳統光槓桿原理所需的複雜光路系統。此外，使用一個由壓電致動器 (piezo-actuator) 所構成的慣性馬達 (inertial motor) 作為待測樣品的載送趨近系統，同時作為垂直方向的掃描致動器。如此整體系統的硬體架構得以最小化，以避免因熱漲冷縮所引起的量測誤差。為了實現進階控制器設計，本論文提出一整合探針-樣品作用關係與壓電致動器之輕敲式原子力顯微鏡數學模型。由於探針的振幅是唯一可得的資訊，我們使用迴路傳輸回復 (loop transfer recovery, LTR) 狀態觀察器來估測狀態資訊，並設計以此觀察器為基礎的可變結構控制器 (variable structure controller) 以增進系統的掃描性能與強健性。實驗結果顯示，本論文所設計之輕敲式原子力顯微鏡可以達到垂直方向正負5奈米之掃描精確度，以及每秒4條線之掃描速度。

關鍵字

輕敲式原子力顯微鏡；光學讀取頭系統；可變結構控制器

並列摘要

A compact tapping-mode atomic force microscope (AFM) utilizing an optical pickup system for measuring the deflection of the probe is presented. An optical pickup head of commercial digital versatile disc read only memory (DVD-ROM) drive is applied in the measuring system. This DVD pickup replaces the quadrant photodiode and complex light path system of traditional optical-lever technique. In addition, an inertial motor composed by a piezo-actuator is used as the sample approaching mechanism and the scanner in the vertical direction. Thus, the volume of hardware structure is decreased, and the sensing variance due to temperature change will be minimized. In order to perform advanced controller design, we propose an integrated system model including the tip-sample interaction and dynamics of the piezo-actuator for the tapping-mode AFM. Because the amplitude of the oscillating probe is the only available information, we use a loop transfer recovery (LTR) observer to estimate system states. Then, the observed-based variable structure controller is designed for enhancing system robustness and performance. From the provided experiment results, satisfactory performances of the proposed AFM system have been successfully demonstrated. The vertical scanning resolution is ±5nm and scanning speed is 4 lines per second.

並列關鍵字

Tapping-mode atomic force microscopy ； Optical pickup head ； Variable structure controller

參考文獻

[1] G. Binning, H. Rohrer, C. Gerber, and E. Weibel, "Surface Studies by Scanning Tunneling Microscopy," Physical Review Letters, vol. 49, pp. 57-61, 1982.

[3] E. Meyer, H. J. Hug, and R. Bennewitz, Scanning Probe Microscopy: Springer, 2003.

[4] J.-A. Ruan and B. Bhushan, "Atomic-scale and microscale friction studies of graphite and diamond using friction force microscopy," Journal of Applied Physics, vol. 76, pp. 5022-5035, 1994.

[5] Q. Zhong, D. Inniss, K. Kjoller, and V. B. Elings, "Fractured polymer/silica fiber surface studied by tapping mode atomic force microscopy," Surface Science, vol. 290, pp. L688-L692, 1993.

[6] J. Tamayo and R. Garcia, "Deformation, Contact Time, and Phase Contrast in Tapping Mode Scanning Force Microscopy," Langmuir, vol. 12, pp. 4430-4435, 1996.

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以光學讀取頭系統實現之輕敲式原子力顯微鏡

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