觀察兩光束在奈米懸浮液中的交互影響

Abstract

從陳致融先前的實驗[07]中，我們知道在特定的條件下能夠觀察到入射的光束在奈米懸浮液中的自聚焦現象，由於這種現象目前並沒有確切的理論能夠解釋，為了要釐清這種自聚焦現象的成因，因此設計一系列實驗來量測。 本論文的各實驗主要是以兩道光的交互作用為主軸，考慮其先後順序與不同的相對位置等不同的組合，來進行研究： 繼承 :在不同或相同的位置先後入射兩道光束，觀察其經過樣品後的光束分布。 導引 :在相同的位置同時入射兩道光束，觀察其經過樣品後的光束分布。 交互作用 :在不同的位置同時入射兩道光束，觀察其經過樣品後的光束分布。 相同位置 不同位置 同時入射 導引 交互作用 先後入射 繼承 繼承 在實驗中兩道光束的大小和功率也是能夠改變的變因之一，因此在多種的組合下，我們選取幾組較具有物理意義的情形來進行比較。 由以上的實驗中，我們統整出形成自聚焦現象，必須要同時滿足幾個必要的條件。分別是在樣品中必須存在著穩定與適當的流場，和光束在樣品的前後方有足夠的散射力差異，當這兩個條件同時滿足後，奈米粒子才能夠在樣品中產生堆積，進而產生自聚焦現象。

Based on past experiment done by Dr. Chen [ 07], one can observe the nanoparticle-concentrating self-focusing phenomenon under certain conditions in a nano-suspension. This phenomenon does not have a clear theory yet. To investigate more about this nonlinear phenomenon, we perform a series of experiments. In this thesis, by designing various types of interactions between two light beams, we deepen the understanding of the nanoparticle-concentrating self-focusing phenomenon. Among these, by considering the relative positions and the sequence of the light, are: Inheriting: The light beams are launched at different moments without time overlaping, while the later one inherits the flow generated by the first one. Guiding: The two light beams are launched at the same position. Interaction: The two light beams are launched at the different locations at the same time. same location different location same time Guiding Interaction different time Inheriting Inheriting In the experiment, we can also vary the power and the beam size of the light beams. We only select the results that possess significant physical meanings to present in this thesis. From these experiment results, we conclude the condition for the formation of nanoparticle-concentrating self-focusing phenomenon. It must simultaneously satisfy at least two conditions, a stable flow field in the sample and the enough longitudinal difference of scattering force along the light beam.