针对空间外差光谱技术测量光谱范围较窄（10 nm左右），制约其应用范围的问题，提出了一种光栅-平面镜结构的可调式空间外差光谱仪系统。该系统将传统的双平面光栅式空间外差光谱仪中的一块光栅换成平面镜，让另一块光栅可旋转来组成可调式结构; 通过旋转光栅切换测量波段，展宽其测量范围；对平面镜施加微小俯仰角以确保谱图还原的单值性；从而拓展了仪器的应用范围。搭建了原理样机并对其性能进行了实验验证。结果表明，设计的仪器的光谱范围达到了100 nm左右，分辨率优于0.29 nm。该仪器结构简单，光栅制作难度低，易于实现谱图还原。另外，通过增加光栅旋转切换次数和引入抑制杂光措施等手段，还可进一步展宽波段范围，提高系统光谱分辨率。

As Spatial Heterodyne Spectroscopy (SHS) technology has a narrower spectral bandpass (about 10 nm) and its applications are restricted generally, this paper proposes a tunable SHS with a grating-mirror structure to widen the application ranges of the spectrometer. The tunable structure in the spectrometer is implemented by taking a plane mirror to replace a grating in the traditional double grating SHS system, meanwhile allowing another grating to rotate. It switches measuring band to broaden measurement range and applies a small pitching angle on the plane mirror to ensure the monodromy of the recover spectra, by which the application ranges of the spectroscopy are expanded. A prototype is established to verify the feasibility of the proposed SHS. The experiment result shows that the designed SHS has the bandpass range up to about 100 nm and its spectral resolution is better than 0.29 nm. The spectrometer has a simple structure and its grating production and spectral reduction are easy to be implemented. Moreover, by increasing the rotated times of the grating and introducing methods to eliminate stray light etc, it will expand the its bandpass farther and improve the spectral resolution.