Abstract: One kind of dichroic filters for protecting the detectors of FIR laser interferometer on HL-2A tokamak is introduced. The geometry of dichroic filters was optimized. The dichroic filters were used on HL-2A FIR laser interferometer system for the first time. The experimental results show that the dichroic filters can effectively isolate the interference from ECRH and make the HCN laser signals keep high transmittance.

Key words: Dichroic filters, Detectors, FIR laser interferometer

摘要： 介绍了用于保护HL-2A装置远红外激光干涉仪探测器的双色滤波器。根据双色滤波器理论优化设计了双色滤波器的外型和结构，并首次用于HL-2A远红外激光干涉仪密度测量系统。实验结果表明，当双色滤波器长度l=0.2mm，直径d=0.23mm，孔之间的间隔s=0.33mm时，双色滤波器能够很好地隔离68GHz的ECRH波带来的干扰，并对890GHz的HCN激光波有较好的透过率。

关键词: 郑 灵, 周 艳, 邓中朝, 易 江, 李永高, 李连才