And so the mirror can only tilt but cannot go down.

着镜子只能倾斜，而不能下降。

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The Michelson interferometer system which has two-beam interference is applied in Fourier Transform interferometer, the moving mirror could tilt in three directions in motion.

采用了双光束干涉的迈克尔逊干涉仪系统的傅里叶变换红外光谱仪，在动镜运动过程中，动镜可能在三个方向发生倾斜。

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If the reference mirror has tilt and piston errors caused by phase-shifting, the phase shifts of the pixels along the same interferogram are not a constant, but they are still kept on the same plane.

当相移器存在的相移误差包括位移误差与倾斜误差时，同一幅干涉图诸像素点的相移并不同步，但其相移量在同一平面上。

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