针对全日盲紫外滤光片, 建立了以窄带光发射二极管(LED)作为基本光源的超大动态范围滤光片带外截止深度测试系统, 并分析了系统的测试误差。该系统主要由LED光源, 已知衰减系数的标准反射式中性衰减片以及光电倍增管组成。基于替代法, 系统测试时将LED光源通过衰减片后的输出电流作为参考电流值替代光源的初始电流值, 通过对比运算获得滤光片的带外截止深度。针对系统中的反射式衰减片, 文中还提出一种组合衰减片方法, 以保证光电倍增管始终工作在线性响应范围内, 从而实现对滤光片的超大动态范围的截止深度测试。实验结果表明, 在350~800 nm谱段内, 该测试系统可测滤光片的带外截止深度延伸至11-OD, 不确定度小于2%, 相对重复性误差小于0.2%。该系统结构简单, 测试谱段范围宽、可测动态范围大且精度高, 可广泛用于滤光片的截止深度测试。

A measuring system for the cutoff depth of out-band of solar blind UV filters with a large dynamic range is proposed by using narrow-band Light Emitting diode(LED) lights as the standard light source. The measuring error of the system is also analyzed. The system consists of LED light sources, the standard reflective neutral attenuators known attenuation coefficients and a photomultiplier. Based on substitution method, the photomultiplier detects the current of the LED through the attenuator as reference to substitute LED initial current, thus the cutoff depth of the out-band of filters is acquired. For the reflective attenuator in the system, an attenuator combination method is presented to insure the photomultiplier working continuously within a linear response range. Experimental results show that the cutoff depth of the out-band of filters is measured to 11-OD in the large spectral range of 350—800 nm. Furthermore, the uncertainty is less than 2% and the relative repeatability error is less than 0.2%. The measuring system has a simpler structure, higher precise, a large spectral range and a wider dynamic range and has been widely used in the measurement of the filter cutoff depth of filters.