全像式水溶液原子力顯微鏡之設計與開發

以全像式光學元件搭配準直鏡及物鏡所組成的光路系統作為原子力顯微鏡的量測單元，目前在空氣中量測已有奈米級解析度的掃描結果，本論文依此架構為基礎，改良光路系統的配置以應用於水溶液原子力顯微鏡上。相較於空氣介質對雷射光的聚焦特性，水溶液介質使聚焦雷射光較為發散，導致反射訊號變弱，量測敏感度下降，進而無法感測出微懸臂在水溶液中的動態特性。為了提升對水溶液中微懸臂的量測敏感度，透過光學軟體模擬以及最佳化光路系統聚焦水溶液中的反射訊號，並藉由實驗分析全像式光學元件的聚焦誤差訊號S 曲線，來驗證模擬的趨勢及結果。微懸臂在水溶液中受到流體阻尼的作用力影響，使其動態特性產生改變，共振頻率、振幅及品質因數Q 值皆下降，透過理論公式的分析及有限元素的模擬來推測其下降的幅度及趨勢，並利用實驗驗證。全像式光路系統整合於水溶液原子力顯微鏡也進行實驗驗證，使用石墨樣品來測試整體系統性能，在水溶液中掃描到約2 nm 的石墨台階位移變化。

關鍵字

全像光學元件；原子力顯微鏡；水溶液；微懸臂；聚焦誤差訊號； S曲線

並列摘要

The aim of this thesis is to design and develop an atomic force microscope (AFM) for measurement in liquid, and its optical measurement system is built up with a holographic optical element (HOE), a collimate lens and an object lens. For the measurement in air, the HOE-AFM can achieve nano-scale resolution. However for the measurement in liquid, the liquid makes the laser beam divergent and ablates the beam reflection, thus the measurement sensitivity can be strongly reduced so that the finest cantilever motion cannot be detected. In order to increase its measurement sensitivity in liquid, the optical simulation software is applied to analyze and optimize the optical system. The performance such as the S-curve of focus error signal (FES) of the developed HOE-AFM is also experimentally tested and verified with the simulated results. The micro cantilever is significantly influenced by the fluid damping effect, which decreases its dynamic properties such as resonant frequency, amplitude and quality factor. Besides the experimental testing, both the theoretical and the finite element analyses are carried out for comprehending the dynamic characteristics of the cantilever in liquid. The developed HOE-AFM system is experimentally verified that it can achieve a measurement resolution of 2 nm for detecting graphite layer in liquid.

並列關鍵字

Holographic optical element ； Atomic force microscope ； Liquid ； Cantilever ； Focus error signal ； S-curve

參考文獻

[1]Binning, G., Rohrer, H., Gerber, Ch., and Weibel, E., “Surface Studies by Scanning Tunneling Microscopy”, Rev. Sci. Inst., Vol. 49, No 1, 1982, pp.57

[2] Benning, G., Quate, CF., and Geber, Ch., ”Ato ic Force Microscope”, Phys. Rev. Letters, Vol. 56, No 9, 1986, pp.30

[3] Huang, Kuang-Yuh, Hwu, En-Te, Chow, Hsin-Yi, and Hung, Shao-Kan, “Develop ent of an Optical Pickup Syste for Measuring the Displace ent of the Micro Cantilever in Scanning Probe Microscope”, Proceeding of the 2005 IEEE: International Conference on Mechatronics, 2005, pp.695-698

[4] Hwu, En-Te, Huang, Kuang-Yuh, Hung, Shao-Kang,and Hwang, Ing-Shouh, “Measure ent of Cantilever Displace ent Using a Co pact Disk/Digital Versatile Disk Pickup Head”, Japanese Journal of Applied Physics, Vol. 45, No. 3B, 2006, pp.2368-2371

[8] Yen, Shih-Hsun, Wu, Jim-Wei, and Fu, Li-Chen, “Apply Tapping Mode Ato ic Force Microscope with CD/DVD Pickup Head in Fluid”, 2010 A erican Control Conference, 2010 , pp.6549-6554

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全像式水溶液原子力顯微鏡之設計與開發

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