以多层介质膜或金属膜为基底的脉冲压缩光栅在利特罗角附近使用，具有衍射效率高、衍射光谱带宽等特点，需要对其衍射光谱进行高分辨率的准确测量，以便为其制作工艺的改进提供可靠依据。根据双光路测量原理，建立了衍射光栅高分辨率光谱测量技术和实验装置。重点阐述了双束光路设计消除光源波动和杂散光对衍射效率测试结果影响的原理，通过光路改进解决了衍射光斑过大，且不能被光探测器完全收集的技术难点以及衍射光与入射光共路导致的探测器挡光问题。该装置可以测量宽带脉冲压缩光栅各级次的反射衍射光谱和透射衍射光谱，也可以测量在固定波长处的衍射角谱分布。目前的衍射光谱测试分辨率为1 nm，角谱分辨率为0.2°。采用该装置测量了脉冲压缩光栅样品的光谱与角谱，在衍射效率超过90%的770~870 nm的衍射带内，多次测量的平均相对偏差小于1.0%，可能的测量误差小于2.2%。

Pulse compression gratings based on multilayer dielectric film or metal multilayer dielectric film usually work around the Littrow angle with high diffraction efficiency and broad diffraction band. There is a large requirement to have high resolution and accurate measurement on the grating diffraction spectrum in the purpose of optimizing the fabrication process. Based on the double light paths system, an optical characterization method and the corresponding setup with high spectral resolution for broadband high diffraction efficiency pulse compression gratings are demonstrated. The method to eliminate the influence of the background and the light source fluctuation is discussed in detail. Two practical problems are perfectly settled, including the large spot size of diffracted light which is not completely collected by optical detector and the detector blocking of the incident light near the Littrow angle. The setup can measure the reflection and transmission diffractive spectra for each diffractive order of broadband pulse compression gratings, as well as the angular spectrum with fixed wavelength. The setup can measure the grating diffractive spectrum with resolution of 1 nm and the grating angular spectrum with resolution of 0.2° at present. The optical spectrum and angular spectrum of pulse compression grating samples are measured on the established measurement setup. Diffraction efficiencies greater than 90% in the wavelength range of 770~870 nm are obtained with measurement error no more than 2.2% and average relative deviation no more than 1.0%.