利用可调谐激光器作为光源，以溯源于低温绝对辐射计的标准辐照度探测器作为传递标准，将可调谐激光导入积分球，通过功率稳定、退相干等措施，形成均匀、稳定、无偏的辐照度场。利用替代定标技术，对太阳辐射计CE318的870 nm直射通道的三个偏振通道（P1、P2和P3）和无偏通道（UP）的绝对光谱辐照度响应度进行了光谱扫描定标，获得这四个通道的光谱辐照度响应度，并预测了大气层顶太阳辐照度的信号值。最后，对定标过程的不确定度进行评价，三个偏振通道和无偏通道的定标不确定度分别达到了1.83%、1.98%、1.73%和1.2%，与Langley定标法定标精度相当。

A new calibration method of absolute spectral irradiance responsivity of sun radiometer named CE318 is described. In this method, a tunable laser and a standard irradiance detector which can be traced from the cryogenic absolute radiometer are used as source and transferring standard, respectively. In the experiment, to acquire the uniform, stable and unpolarized irradiance field, the laser which is stabilized by a laser power controller, wavelength by wavelength, is steered into an integrating sphere with which a speckle-removal device is equipped. By the vicarious calibration technique, the spectral irradiance responsivities of the 870 nm sun channels of CE318 consisting of three polarized channels (P1, P2 and P3) and an unpolarized channel (UP) are obtained and used to predict the top-of-the-atmosphere signals, respectively. In the last, the uncertainties of calibration are evaluated and reach to 1.83%, 1.98%, 1.73% and 1.2%, which are comparable to the counterparts of Langley method, the main method of calibration in this field.