200～400nm短波紫外光谱辐射照度国家基准装置的研究与建立

针对我国短波紫外光谱辐射照度测量能力缺失的问题，基于高温黑体辐射源，2017年中国计量科学研究院NIM自主研制了200~400 nm光谱辐射照度国家基准装置。组建氘灯副基准灯组，实现基准量值的独立复现、保存和传递。在国内形成了以氘灯为传递标准的光谱辐射照度计量基标准和量传体系，为各应用领域提供最高溯源标准。针对基准系统中温度测量、带宽、信噪比、荧光等主要误差源，逐一突破关键测量技术，提升基准的测量准确度：将高温黑体的温度测量直接溯源至铂-碳Pt-C和铼-碳Re-C固定点黑体，采用钨碳-碳WC-C高温共晶点测温技术进行验证，在3 021 K固定点与俄罗斯计量院VNIIOFI的偏差仅0.07 K，将200 nm的测量不确定度减小0.2%；针对黑体和氘灯光谱形状显著差异导致的光谱带宽误差，提出基于微分求积的七点带宽修正法，在200 nm，误差减小0.86%；提出绝对和相对互补型测量原理，将200 nm的测量重复性误差减小约20倍；采用选择性滤波技术，成功消除系统内荧光对测量结果的影响。3 021 K时黑体温度的测量不确定0.64 K，腔底不均匀性小于0.17 K，测量期间黑体温度漂移小于0.2 K，双光栅单色仪的波长误差不超过±0.01 nm。氘灯副基准的标准测量不确定度为：200~250 nm，U_rel=4.0%~1.3%；250~330 nm，U_rel=1.3%~1.2%；330~400 nm，U_rel=1.2%~1.9%，整体技术指标达到国际先进水平。研究成果填补了200~400 nm基于氘灯的光谱辐射照度国家基准的空白，使我国具备能力参加国际计量局组织的CCPR-K1.b国际关键比对，与传统以卤钨灯为传递标准的光谱辐射照度国家基准实现了有效衔接。在250~400 nm重合波段，两种传递标准量值的平均相对偏差为0.39%，在声称的不确定度范围内一致。

Realization of National Primary Standard Apparatus of Spectral Irradiance from 200 to 400 nm

Aiming at the problem of lacking national measurement ability of short UV spectral irradiance, based on high temperature blackbody source, national primary standard apparatus of spectral irradiance in the spectral wavelength from 200 to 400 nm was developed independently at NIM in 2017. A group of stable deuterium lamps were used to maintain and disseminate the scale of spectral irradiance in short UV wavelength. New traceability system based on deuterium lamps was setup to provide the highest standard for the application fields. As to temperature measurement, spectral bandwidth, signal to noise ratio, fluorescence in the system, series new methods and key measurement technology were adopted to cut down the main error sources. The temperature measurement of blackbody was traced to Pt-C and Re-C fixed point blackbody, and checked against the WC-C fixed point blackbody. The deviation between NIM and VNIIOFI (All Russian Research Institute for Optical and Physical Measurements) at 3 021 K was 0.07 K, and measurement uncertainty at 200 nm was cut down by 0.2%. Owing to the great difference of spectrum between blackbody and deuterium lamp, the bandwidth effect of the monochromator should be considered. A seven point bandwidth novel correction method based on differential quadrature formula was put forward to correct bandwidth error 0.86% at 200 nm. Absolute and relative measurement principle was adopted to reduce the repeatability uncertainty about 20 times at 200 nm. A selective filter method was used to remove fluorescence in the primary standard apparatus. The standard measurement uncertainty of temperature was 0.64 K when BB3500 M blackbody was operating at 3 021 K, and the non-uniformity was less than 0.17 K over the effective diameter. The maximum shift of the temperature of the blackbody was less than 0.2 K during measurement period. Wavelength error of the double grating monochromator was less than ±0.01 nm. The standard measurement uncertainty of the secondary primary standard of spectral irradiance were 4.0% at 200 nm, 1.3% at 250 nm, 1.2% at 330 nm, 1.9% at 400 nm respectively. The establishment of new primary standard apparatus is based on deuterium lamps from 200 to 400 nm, which is possible for NIM to participate the international key comparison CCPR-K1. b sponsored by the International Bureau of Weights and Measures (BIPM). Wavelength range of the new primary standard is linked up with the original primary standard of spectral irradiance based on tungsten halogen lamps. In the overlap wavelength from 250 to 400 nm, the average deviation between two kinds transfer standard lamps, deuterium lamp and tungsten halogen lamp, was verified to be less than 0.39%, which was consistent with the associated measurement uncertainty.