请翻译偏振方向示意图如图1b所示。圆柱型铷原子气室主轴延z轴方向放置；探测光与耦合光沿z轴反向传播偏振方向沿x轴且平行于水平面；微波信号沿y轴向下传播偏振方向在x-z平面内将微波偏振方向与激光偏振方向夹角设为$theta$ $theta in 090$。并进行润色。

The schematic diagram of polarization direction is shown in figure 1(b). The cylindrical rubidium atomic cell is placed along the main axis in the z direction. The detection light and the coupling light propagate in the opposite direction along the z axis, and the polarization direction is along the x axis and parallel to the horizontal plane. The microwave signal propagates downward along the y axis, and the polarization direction is in the x-z plane. The angle between the microwave polarization direction and the laser polarization direction is set to $\theta$ ($\theta \in [0,90]$).

（润色：对原文进行了一些修改，使得句子更加通顺，表述更加清晰。）