本論文的研究工作主要是利用Mach-Zehnder干涉儀,並結合相位移干涉術,達成對磁光阱中所捕獲之銣原子的非破壞性、無透鏡式成像。此一成像方式的優點為不需加入透鏡。因此,可以避免因透鏡所造成的任何相差。此外,因該成像屬於雙光束方式,因此可以藉由光強較強的參考光束增強整體干涉訊號,以便使用極弱的探測光便可以對冷原子樣本達成高訊噪比成像。 無透鏡式成像方法,主要利用遠離原子共振頻率之雷射光通過冷原子與自由空間之兩束光的遠場干涉訊號,藉由CCD相機擷取後,重建冷原子的近場相位影像。並由此還原出冷原子之空間密度分佈。利用相位移干涉術,並經由干涉儀來確定探測光的相位,擷取探測光通過冷原子產生額外的相位變化與沒有通過原子的參考光干涉後成像於CCD相機。此法主要將參考光及探測光的干涉訊號分別調在0度、90度、180度、270度,取出四張遠場干涉影像,藉此回推出冷原子團的空間密度分佈。 本實驗中,除建立相位移干涉術之系統量測銣原子團樣本,我們並從已知的實驗參數與理論模擬做匹配來驗證成像方法。該理論模擬部分已由本實驗室陳竑學學長完成。本實驗則證實該理論之預測,而實驗結果亦證實該非破壞性、無透鏡式的冷原子成像法。
We experimentally demonstrate the lens-free nondestructive phase shifting imaging on 87Rb magneto-optical trap (MOT) by using a Gaussian beam and accompanying with phase shifting interferometry . This scheme requires no imaging lens. Hence, aberration associated with it is completely eliminated and mechanical focusing can be avoided. Compared to the common single-beam nondestructive means , our proposed scheme allows energy per probe pulse delivered to the cold samples lowered by almost three orders of magnitude due to signal enhancement inherently provided in the two- beam configuration .Our experimental realization of this novel nondestructive detection means for in-situ imaging on the rubidium-87 atoms trapped in a MOT. Besides, we will demonstrate the focusing capability provided in this scheme as well, though no imaging lens is used.