黑体的温度越高,太赫兹波段辐射量越大,测试信噪比越高，但红外辐射量增大的幅度远大于太赫兹辐射量，难以滤除，滤除效果不好则会降低黑体太赫兹辐射测试的准确度。为了准确测试黑体的太赫兹辐射量,选择了合适温度范围的黑体，设计了其太赫兹辐射量测试方法。首先，根据普朗克公式计算温度范围在3～600 K的黑体在太赫兹宽波段和红外波段的辐射出射度以及在不同太赫兹窄带波段的辐射出射度，分析了相对变化趋势；其次，提出了黑体太赫兹辐射锁相探测方法,选择的太赫兹黑体温度范围为223～273 K。实验结果显示，在此温度范围内，黑体在100～3000 μm波段的太赫兹相对辐射量与实测相对值的误差范围为0.1%～2.0%，且曲线变化趋势一致,说明该方法能够实现黑体太赫兹宽波段辐射量测试。

The higher the temperature of a blackbody, and the greater the amount of radiation of the terahertz band, the higher the test signal-to-noise ratio, but at the same time the increase of the amount of infrared radiation is far greater than that of terahertz radiation. The infrared radiation is difficult to filter and the blackbody terahertz radiation test accuracy is reduced. To improve the test accuracy, a suitable temperature range is chosen for the blackbody and the test method is designed for its terahertz radiation. Firstly, the distribution of spectral radiant emittance in the terahertz and infrared wave bands is calculated by Planck′s law for the blackbody at temperatures between 3~600 K. The radiation difference of blackbodies in this two wave bands is analyzed. Then the relative changes of radiation at different terahertz narrow band wavelengths for blackbody at the same temperature are analyzed. The phase-locking test method for blackbody in terahertz band is put forward, with the suitable blackbody temperature range of 223~273 K. The experimental results show that the terahertz test relative deviation is 0.1%～2.0%. The terahertz test curve is consistent with the related theoretical curve for blackbody in 100~3000 μm at this temperature range.