雷射鎖頻在原子分子結構研究、精密量測、光纖通訊與原子鐘等研究上是重要的課題，利用原子分子躍遷光譜可作為雷射鎖頻的依據，得到頻率精準的雷射光。

本實驗量測氦-四氣體躍遷波段位於1083 nm附近，對應躍遷譜線D1及D2線的偏振光譜譜線。利用擬合軟體Origin以高斯函數分析頻寬及譜線形狀，並以都普勒線寬公式算出該氣體分子團的溫度。

The laser frequency stability is an important topic in varies AMO research realms, such as molecule structures, optical-fiber communication, metrology, and the atomic clock. One of the trustable reference to facilitate frequency-locking is atomic spectroscopy.

We measured the polarization spectroscopy of gaseous helium-4, around the 1083-nm D1 and D2 transition lines. By using the Origin software, we fit the data with the Gaussian distribution function, analyzing the line-shape, and calculating the temperature of the gases by the Doppler broadening equation.

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