整合單光束光鉗與平面彎曲式光柵在微粒操縱之研究

Integrated Single-Beam Optical Tweezer and Planar Curved Grating for Microbeads Manipulation

陳冠宇(Kuan-Yu Chen)

指導教授 ： 郭如男

國立虎尾科技大學/工程學院/機械與機電工程研究所/碩士(2009年)

摘要

本論文將介紹光鉗系統的工作原理、光鉗的架設方法、系統光路校正與光鉗系統鉗住微粒子的實驗程序，對於光鉗系統的鉗住力、黏滯力、散射力和雷射的折射角度計算做探討，以了解光學鉗住現象。並利用面型微加工製程設計與微機電系統代工製程(MUMPs)，製作出不同曲度的平面彎曲式光柵，觀察雷射光入射光柵所產生的繞射圖形，計算出垂直繞射角與水平繞射角，並推導出繞射角與曲度的關係式。最後將光鉗入射結合光柵所產生的繞射圖形，讓光鉗可同時鉗住多顆微粒，發展出多重光鉗系統，以提升鉗住效率。
本實驗架設一單光束光鉗系統，雷射功率為2.4 mW時便可捕捉操縱直徑3微米大小的聚苯乙稀粒子，並計算出光鉗黏滯力FD = 0.46 pN；另外，藉由平面彎曲式光柵繞射繞射角與曲度的關係，可推導出相對應公式：一階公式：Φ=2475.11κ+3.86與二階公式：Φ=3537.57κ+7.81，其中Φ為垂直繞射角度，κ為彎曲式光柵之曲度，推算之公式能計算出不同曲度所對應之繞射角度，而且與最小平方法所算出之公式相符合。

關鍵字

光鉗 ； 微機電系統 ； 平面彎曲式光柵 ； 繞射

並列摘要

This paper presents a single-beam optical tweezer integrated with surface micromachined grating for microbeads manipulation. A laser power of 2.4 mW was sufficient to trap a 3-μm-diameter polystyrene sphere. The laser power of 10 mW has a dragging force of 0.46 pN. The planar curved grating was fabricated using Multi-User MEMS Processes (MUMPs) provided by MEMSCAP Inc. When the collimated beam passes through the planar curve grating will produce diffraction patterns. Experimental indicates that the diffraction patterns and the curvature of planar curved grating reveal a close relationship. As the curvature of planar curved grating increases, the vertical diffraction angle linear increases. Therefore, a formulation for the relationship between the vertical diffraction angle (Φ) and the curvature of planar curved grating (κ) is thus proposed to be Φ=2475.11κ+3.86 for first order diffraction and Φ=3537.57κ+7.81 for second order diffraction. Finally, we demonstrate the multi-trapping of beads in water with a microfabricated planar curved grating.

並列關鍵字

Diffraction ； MEMS ； Optical tweezer ； Planar curved grating

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