中阶梯光栅光谱仪凭借着高分辨率、小体积、全谱瞬态直读等优异特性成为了现代光谱仪器研究的热点和重点。为了进一步缩小它的体积，提高仪器信噪比和检出限，设计了一种新型结构的中阶梯光栅光谱仪，其折叠主光路的设计可以在不改变成像质量、不降低光谱分辨率的前提下减小仪器体积，光学尺寸小于165 mm×70 mm×65 mm，光谱分辨率为0.06 nm@200 nm。同时设计了挡板、光阑等结构减小仪器的杂散光，经过光线追迹仿真实验，新型中阶梯光栅光谱仪杂散光低于2×10-5，显著地提高了仪器的信噪比。

Echelle spectrometer is becoming a hot research and focus of modern spectrograph with the outstanding features of high resolution, small size, full spectrum transient direct- reading. In order to further refine its volume, improve the signal to noise ratio and the detection limit, a new structure of echelle spectrometer is designed. By folding main optical path, the new design has smaller size and lower stray light without reducing spectral resolution and image quality. It′ s optical size is less than 165 mm × 70 mm × 65 mm, and spectral resolution is 0.06 nm@200 nm. The baffle and diaphragm is designed to further reduce stray light. Through ray tracing simulation, the stray light of the new echelle spectrometer is less than 2×10-5 , the signal to noise ratio is improved significantly.