傅里叶变换红外光谱仪动镜倾斜误差分析

Error analysis of moving mirror in Fourier transform interferometer

通过建立傅里叶变换光谱仪中动镜、定镜和干涉面的坐标对应关系,对动镜存在多个方向倾斜时的干涉光路进行了详细的分析。建立了非准直状态下干涉面光强分布的二维数学模型,确立了干涉图函数的数学表达式,从调制度、相位误差和频率噪声的角度,对动镜倾斜造成的影响进行了系统分析。在动镜的运动中,左右方向的倾斜和俯仰方向的倾斜对系统的影响彼此具有独立性,又具有叠加性;干涉图中初相位因子随光程差改变缓慢变化或快速变化,对相位误差的影响也不全相同。在倾斜误差分析的基础上,对动镜的最大倾斜角度和减少误差的方法进行讨论,并提出了两种动态准直校正的思路。

Based on the coordinate correspondence of the moving mirror, fixed mirror and interference surface in Fourier transform interferometer,the interference mode was analyzed under moving mirror tilted in several directions. In tilting status, a two dimension mathematical model of the interference plane was brought out, and the function of the interferogram was established. By analyzing the modulation depth, phase error and frequency noise,the error of the moving mirror were studied theoretically. It is found out that the different titling directions of moving mirror affect the system error independently, at the same time they can be added. The original phase of the interferogram is changedslowly or rapidly with the optical path difference changed, and the phase error is different too. Based on the error analysis, the max titling angle can be computed, two methods to keep adaptive alignment are also discussed.