碘分子的躍遷譜綫由於大多分佈在可見光範圍以及很密集，所以碘分子的穩頻系統常用來當作雷射頻率參考源。
在這個實驗我們使用1079 nm 的外腔式半導體雷射作為光源，並使用倍頻晶體將波長倍頻至539.5 nm。然後通過頻率調製光譜鎖頻以及偏頻鎖頻的方法來測量碘分子R(81)29-0 躍遷的超精細分裂譜綫間距。實驗值與程式IodineSpec5 計算值相比，差值都在60.1 kHz 以内。此外，我們也測量了此躍遷的壓致偏移以及壓致增寬，分別爲11.18 ± 0.8 kHz/Pa 和88.2 ± 2.2 kHz/Pa。
然後，我們也將雷射頻率鎖在R(81)29-0 躍遷的a_1 譜綫上，并於另一臺穩頻雷射拍頻取得Allan deviation，頻率穩定度在積分時間為10 秒時可以達到6 × 10^(−12) 的等級。

Laser stabilizing system are frequently used as laser frequency reference since transition spectral line of iodine molecule are dense and are mostly distributed at visible range.
In this experiment we use a 1079 nm External Cavity Diode Laser (ECDL) as light source, and frequency doubling into 539.5 nm. Next we measure the spacing of R(81)29-0 hyperfine transition lines by using frequency modulation spectroscopy and offset locking system. The difference between experimental value and calculated value from program IodineSpec5 is below 60.1 kHz. We also measured the pressure shift and pressure broadening of this transition, which is 11.18 ± 0.8 kHz/Pa and 88.2 ± 2.2 kHz/Pa respectively.
Furthermore, we locked our laser frequency on a1 spectral line of R(81)29-0 transition, and obtain Allan deviation of beat frequency with another frequency stabilized laser. After 10 s time integration, the frequency stability can arrived 6 × 10^(−12).

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