对基于多级微反射镜的傅里叶变换红外光谱仪进行了光学分析，研究了光源尺寸、光强分布的不均匀性和光学系统像差等因素对光谱复原的影响。发现光源尺寸影响光谱分辨率，光强分布的不均匀性和光学系统像差会产生基线噪声。数值计算的结果表明，当光阑的尺寸小于2.5 mm，不均匀的标准偏差小于0.5，准直系统的波像差均方根值小于0.05，以及缩束成像系统的光斑直径小于30 μm时，光谱复原的噪声可以忽略。给出了光学系统的设计结果。

The optical properties of the Fourier transform spectrometer such as the size of source, the ununiformity of the intensity and the aberration of the optical system are analysed. It is shown that the large size of source caused the double peaks and lower spectral resolution, the ununiformity and the aberration cause the noises on the base line. The numerical results show that the noises can be ignored as the size of source at the stop is smaller than 2.5 mm, the standard deviation of intensity is smaller than 0.5, the root-mean square (RMS) of wavefront aberration for the collimating lens is smaller than 0.05 waves, and the RMS of spot diameter for constricted lens is smaller than 30 μm. The design of optical systems is proposed.