在高精度光谱定标实验中，倾斜漫反射板光谱定标和直接照射光谱定标两种方法得到的定标结果存在微小差异。对光谱定标的能量传输过程进行分析，发现光通过倾斜的漫反射板照射到仪器的入射狭缝时，入射狭缝表面的辐射通量分布出现不对称现象，引起波长差异。以光栅双单色仪为例，将出射狭缝处不同波长偏差所对应的辐射通量曲线进行叠加，得到应用45°倾斜的漫反射板进行光谱定标时的波长差异为-0.0283 nm。最后以汞灯为光源，以296.7283 nm和365.0157 nm两个波长为定标波长，采用漫透射板垂直照射和45°倾斜的漫反射板照射两种方法对光栅双单色仪进行光谱定标，两种定标方法结果偏差分别为-0.029 nm和-0.0286 nm。证明倾斜漫反射板是引起波长差异的主要原因，并为漫反射板光谱定标提供数据。

In the experiment of high-precision spectral calibration, the results of spectral calibration, when using the tilt diffuse reflector as dodging device, are different from vertical exposure. Through analysing the process of energy transfer, we find that the radiant flux on the entrance slit is uneven when using the tilt diffuse reflector, which causes the wavelength difference. We use the double grating monochromator as the instance, and put all of the radiant flux of different wavelengths on the entrance slit. And then we can know that wavelength difference is -0.0283 nm, when using the 45°tilt diffuse reflector to wavelength calibration. Finally, making the mercury as light source, by scanning the 296.7283 nm and 365.0157 nm wavelengths with two methods of using the diffuse transmittance plate to vertical irradiation and using the 45° tilt diffuse reflector plate irradiation, the wavelength difference are -0.029 nm and -0.0286 nm. The results of the experiment can certify that the tilt reflect diffuser is the main factor to cause the wavelength difference in the spectral calibration experiment.