实验室试验和多年实践经验都表明，设计良好的灯具配用一种吸收性过滤器——活性炭，使其因内部污染造成的光衰降至平均每年为１％。相反，目前使用的设计良好而不用过滤器的灯具，反光镜表面积累的污染物使光输出降低的速率平均为每年４％～５％。在室外，由折射器外部污... Laboratory tests and many years of practical experience have shown that well-designed lamps and lanterns with an absorption filter - activated carbon, so that the light pollution due to internal pollution down to an average of 1% per year. In contrast, currently well-designed, filter-free luminaires use about 4% to 5% annual reduction in light output due to accumulated pollutants on the mirror surface. Outside, by the refractor external dirt ...