弱场偏振探测技术灵敏度及噪声的定性分析

弱场偏振探测技术是分子取向探测技术的一种。该探测技术不会破坏无外场取向分子的量子状态从而便于取向后的分子进行各种实际应用,因此这种技术在分子取向的研究中运用较为广泛。详细介绍了弱场偏振探测技术和其改进技术——平衡弱场偏振探测技术的探测原理和实验系统组成,以泰勒级数为基础采用近似方法分析、比较了两种探测技术的灵敏度,探讨了二者的噪声来源和影响。研究发现,在分子取向度较小时,后者的灵敏度比前者较强;探测激光能量涨落较大时,后者的噪声明显低于前者;探测激光能量涨落可以忽略时,二者的噪声大小比较接近。

Qualitative analysis of the sensitivity and the noise of weak field polarization detection technique

Weak field polarization detection technique is one of detection techniques of the molecular alignment. This method does not damage the quantum state of the field-free aligned molecules, thus it is convenient for the further applications of these aligned molecules. The principles and the experimental schematics of the weak field polarization technique, and its improvement-balanced weak field polarization detection technique were introduced in detail. Based on the Taylor series approximation, the sensitivity of these two techniques were analyzed and compared. The original noises of these two techniques were investigated as well. The study found that the sensitivity of the latter is higher than the former when the alignment degree of the molecules is lower. The noise of the latter is lower than the former when the fluctuation of the laser pulse energy is obvious. The noises of the two techniques are close when the fluctuation of the laser pulse energy can be ignored.