隨著雷射冷卻技術的發展，透過光結合法或費許巴赫共振法可來產生極冷分子，為了探側極冷分子是否存在，目前的方法大部分為破壞性的偵測法。我們試圖探索一種非破壞性方法的可能性：直接偵測分子螢光並利用外差干涉技術來獲得是否有分子形成的資訊。而我們第一步便是用此方法來偵測銣原子磁光陷阱的螢光來了解實行的可能性。
　　同時，我們使用新的雷射光源並重新架設了磁光陷阱的系統，偵測影像系統也更趨於完整。最後利用外差干涉的技術成功地觀察到銣原子磁光陷阱螢光的拍頻訊號，說明未來此方法偵測極冷分子之可行性。

In this thesis, we explored the possibility of a non-destructive method, "a heterodyne interference technology", which probes the existence of ultra-cold molecules. First step, we test this method by observing the beat signal from the fluorescence of atomic Rb in Magneto-optical trap. The success of this experiment implies that we can start the next step of probing ultra-cold molecules with this heterodyne technology.

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