| Summary: | 碩士 === 國立高雄應用科技大學 === 光電與通訊工程研究所 === 105 === These are three phases in this study. In the first phase, fiber microlenses are sequentially made by wet chemical etching and laser melting. The resultant lenses are analyzed to obtain their cone angles or radius of curvature by an image processing code written in MATLAB. In the second phase, a cone-shaped or hemisphere-shaped microlens is selected to construct an optical tweezer. A 650 nm laser is used as the light source of the system. In the third phase, four optical trapping experiments are conducted individually on polystyrene particles and yeasts. The effect of different shapes of fiber microlenses on the trapping efficiency of optical tweezers is investigated by changing the incline angle for trapping, the sample diameter, and the microlens shape.
In the experiment of trapping polystyrene particles, an optical tweezer contains a cone-shaped fiber microlens. The optimal trapping efficiency is about 8.1%. However, if an optical tweezer contains a hemisphere-shaped fiber microlens, the optimal trapping efficiency is about 10.1%. The results show a linear relationship between the diameter of particle and trapping efficiency. In the experiments of trapping on beer yeasts, if an optical tweezer contains a cone-shaped fiber microlens, the optimal trapping efficiency is about 5.4%. On the other hand, if an optical tweezer contains a hemisphere-shaped fiber microlens, the optimal trapping efficiency is about 2.8%. The results show that the trapping efficiency of the optical tweezer is greatly affected by the shape of the fiber microlens.
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