磁旋转腔增强光谱技术

为了提高吸收光谱的探测灵敏度,在弱吸收或短光程吸收的情况下实现高灵敏探测,将腔增强光谱技术与磁旋转光谱技术有效地结合起来,发展了高灵敏的磁旋转腔增强吸收光谱技术,并通过测量O2 的三重禁戒跃迁谱线验证了该技术的探测灵敏度。实验采用环型增强腔,以避免光束的返回对激光器的干扰。给出了腔的耦合匹配条件,以及镜面反射率、腔损耗对增强因子的影响;同时也给出了在实验中对光谱信号的处理方法。测量结果表明,在谐振腔精细度为F=48,腔内总损耗为13%,以及腔镜的耦合效率为 95%的情况下,对 O2 分子最小相对吸收度约为4.5×10-8(1 s积分时间)。

Magnetic Rotation Cavity Enhanced Spectroscopy

To improve the detection sensitivity in the conditions of weak absorption and/or short absorption path, a highly sensitive spectroscopy, namely magnetic rotation cavity enhanced absorption spectroscopy, was developed by combining cavity enhancement with magnetic rotation techniques together, where a ring shape external cavity was adopted as the signal enhancement to avoid the perturbation of the return beam to the laser source. The qualifications of mode matching together with the dependence of the enhanced factor on the mirrors' reflectivity and the cavity loss were presented; moreover, the process of the spectroscopic signal in the experiments was also discussed. As an example, this spectroscopy was employed to observe the spectrum of the triply forbidden transition of O2, and the minimum detectable absorption was measured to be about 4.5×10-8 (1 s integrated time) with 95% coupling efficiency, 48 finess and 13% total loss of the cavity.