窄带光谱滤光法探测低温黑体太赫兹辐射

摘要

To detect the terahertz radiation of a low temperature blackbody accurately,the difference between infrared radiation and different terahertz radiations of the blackbody was researched.A low temperature blackbody terahertz radiometer was established with narrowband spectral filtering method.First,the emitted spectral radiances were calculated by Planck's law in various terahertz wave bands.The results show that the radiances of blackbody in the infrared band are four to ten times than that in the terahertz band from 223 K to 323 K.Then a low-pass filter and several band-pass filters were made up a filter combination with high transmission in various wavelengths.The filter combination was used to filter the infrared radiation and to transmit the terahertz radiation to implement the terahertz spectral radiance measurement.Experimental results reveal the deviations of terahertz narrowband radiations at different bands for the blackbody and indicate that spectral filtering method can realize the detection of terahertz radiation of the blackbody.%为了准确探测低温黑体的太赫兹辐射,研究了黑体的红外辐射和太赫兹各波段辐射的差异,构建了低温黑体太赫兹辐射探测装置,提出在该装置中采用窄带光谱滤光法抑制红外辐射和透过窄带太赫兹光谱.根据普朗克公式计算并对比了各波段太赫兹辐射及红外辐射的亮度值,理论数据显示223～323 K的低温黑体的红外辐射亮度是太赫兹辐射亮度的4～10倍.将在某一窄波长带宽范围内具有高透射比的太赫兹窄带光谱滤光片放置在黑体太赫兹辐射装置的探测器前,滤除红外辐射,并对黑体的太赫兹辐射量进行光谱分段探测实验.根据实验结果计算了黑体在不同太赫兹窄波段的辐射探测值的标准偏差,并对实验结果与黑体太赫兹辐射亮度理论计算值进行了比较.结果显示,窄带光谱滤光法可以实现低温黑体的太赫兹窄带辐射亮度探测.