我們呈現了一種能產生具準直性的鋰原子束的設計與構造，大約250根的微小管子被聚集在一起，大量的增強原子蒸汽和管壁間的碰撞，使得原子束的準直性被優化。
我們將雷射頻率共振於鋰原子的D_2躍遷頻率上，並利用原子束和雷射垂直作用所產生的螢光決定原子束的特性。文中我們將討論原子束的特性，如：原子束流量、發散角、原子速度與烤爐溫度間的關係。使用這樣的設計，我們可以改善鋰原子2S-2P與2S-3P躍遷的螢光訊號的雜訊比，以及減低其訊號線寬，由此得到精密的雷射光譜。

We present the design and construction for an effusive oven that generates a collimated lithium atomic beam. Approximately 250 stainless-steel microcapillary tubes are assembled together so that the collisions between the atomic vapor and the tubes are largely enhanced to improve the collimation of the atomic beam.
The atomic beam is then characterized by shinning a laser beam perpendicular to the atomic beam and the laser frequency is resonant with lithium D2 transition. The characteristics of the atomic beam, including the atomic beam flux, divergent angle, and the atom velocity versus oven temperature is discussed. Using our design, we can improve the signal-to-noise ratio and reduce the linewidth of the laser-induced fluorescence signal of lithium 2S-2P and 2S-3P transitions so that precision laser spectroscopy can be performed.

Chapter1 Introduction 1
1.1 Atomic and molecular beam 1
1.2 Motivation 2
Chapter2 Theory 3
2.1 Fine structure 3
2.1.1 First-order relativistic correction 3
2.1.2 Spin-obit coupling 4
2.2 Hyperfine structure 5
2.2.1 Magnetic dipole interaction 5
2.2.2 Electric quadrupole interaction 6
2.3 Doppler broadening effect 7
2.4 Saturation spectroscopy 9
2.5 Cross beam method 11
2.6 Knudsen diffusion 13
Chapter3 Experiment 15
3.1 Laser system 15
3.2 Lithium atomic beam 17
3.2.1 Oven design 17
3.2.2 Nozzles design 20
3.2.3 Vacuum system 22
3.3 Fluorescence detection 24
3.4 Optical layout 26
3.4.1 Saturation spectroscopy 26
3.4.2 Stable laser system with stable Fabry-Perot cavity 27
3.4.3 Stable laser system applying Frequency modulation 29
3.4.4 Atomic beam measurement 30
Chapter4 Result and Discussion 32
4.1 Frequency stabilization 32
4.1.1 Saturation spectroscopy 32
4.1.2 Stable laser system with stable Fabry-Perot cavity 34
4.1.3 Stable laser system applying Frequency modulation 37
4.2 Characteristics of atomic beam 39
4.2.1 Spectroscopy of lithium D2 line 39
4.2.2 Divergence angle 40
4.2.3 Atomic beam flux 42
4.3 Result discussion 45
Chapter5 Conclusion 47
Chapter6 Bibliography 49
 

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