采用Ｍ型棱镜分光束法研制了一台全自动扫描绝对反射率光谱仪，测量光谱范围为３５０ｎｍ～８２０ｎｍ（１．５～３．５ｅＶ），样品入射角为５°，测量和数据采集处理全过程由计算机控制．测量绝对值精度优于±１％，测量重复性优于０．１％．采用本谱仪对热蒸发金膜和（１１１）锗本征体单晶进行测量，获得了与椭偏测量以及文献报道相一致的结果． A fully automatic scanning absolute reflectance spectrometer was developed by using the M-type prism sub-beam method. The measuring range was from 350nm to 820nm (1.5 ~ 3.5eV) and the sample incident angle was 5 °. The whole process of measurement and data acquisition Controlled by computer The accuracy of the absolute value of the measurement is better than ± 1% and the repeatability of the measurement is better than 0.1%. The spectrometer was used to measure the thermal evaporation gold film and (111) germanium intrinsic crystal single crystal, and the results consistent with the ellipsometry and reported in the literature were obtained.