本研究探討一具有三維入口流道與主流道側邊凹槽的微光流體聚光器，它會使流經主流道的流體產生漸進式折射率梯度，使光線在垂直光線主要行進方向的截面上往中間聚焦以改進聚焦效果。本研究將氯化鈣水溶液(即初始溶液，做為核心流體)與去離子水(即水，做為包覆流體)混合成工作流體，將流體由左右對稱的四個入口注入流道內，其中左右兩個入口為去離子水入口(B入口)，包覆中間深度較淺的氯化鈣水溶液入口(A入口)，使注入流體時低折射率的流體能包覆高折射率的流體，形成中間高左右兩側低的折射率分佈，使光線通過主流道時會朝中間高折射率區域前進，達到聚光的效果，並可以藉由控制入口流率的方式，改變流道內的折射率分佈，來調整光線的聚焦位置。本研究使用數值模擬軟體ANSYS Fluent模擬流道內的速度場及濃度場，再以自行寫作的C++程式進行光線追跡，模擬光線經過流道時的軌跡。接著對流道的幾何參數與流率參數進行最佳化，其中選定的幾何參數如下：主流道長度 、主流道側邊凹槽寬度 及A入口深度h，流率參數如下：A入口流率 、A與B入口的流率比 ，先固定流率參數，以田口法尋找幾何參數的最佳參數組合，再固定幾何參數，以全因子實驗規劃尋找入口流率參數的最佳參數組合。本研究使用微影製程製作微聚光器，選用最佳的參數組合進行實驗，用數位單眼相機連接顯微轉接鏡與可變焦顯微觀察系統，由流道上方觀察及拍攝光線在聚光器中的光線軌跡，比較實驗結果與數值模擬的結果相近，得知模擬可靠。由模擬結果可知：A入口流率會影響工作流體的擴散程度，A與B入口的流率比會影響主流道內的折射率梯度，藉由控制流率參數可以用來調整光線的聚焦位置。三維流道由於其折射率分佈亦呈現三維分佈，聚焦效果比二維流道好。

In this work, we propose and investigate a micro optofluidic beam condenser with three-dimensional (3D) inlets and side groove of main channel. Calcium chloride solution (n=1.41) and deionized water (n=1.33) are applied as the core and the cladding liquid, respectively. Two deionized water inlets lie on both sides of the calcium chloride solution inlets. The latter is shallower than the former in depth, so the cladding liquid would wrap around the core liquid to form gradient refractive index (GRIN) in the main channel. The beam passing through the main channel will converge toward both the middle vertical plane and the horizontal plane by the GRIN. Furthermore, we can adjust the inlet flow rate to change the GRIN, and so change the focus length of the beam. ANSYS Fluent and self-developed codes are used to simulate the flow field and the light propagation, respectively. Taguchi method and full-factorial experiments are used to optimize different geometry and flow parameters to enhance the performance. The validity of simulations is confirmed by the experiment. We can see that the 3D structure of the beam condenser improves the performance, and by adjusting the flow rate parameters, we may adjust the focus of beam.

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