提出了一种新型的基于反射光栅干涉仪的低背景光谱仪,当使用工作在背景限制条件下的探测器时,降低背景噪声,有利于提高光谱仪系统的探测率,进而可提高光谱仪的信噪比.由于理想反射镜发射率为零,故其干涉仪组件无黑体辐射.因此,基于低温光源、低温探测器和光栅干涉仪的光谱仪,其探测到的背景辐射大幅降低.进而得到低背景下的探测率实现灵敏探测.理论分析表明随背景辐射的降低,背景限制条件下探测器的探测率可大幅提高.理想情况下,对工作在背景限制下的碲镉汞探测器,当由300 K的背景辐射降至77 K时,其探测率和相应光谱仪的信噪比可提高三个数量级.另外,与之前报导的低温迈克尔逊光谱仪相比,它结构紧凑且无需对干涉仪降温,易于搭建.该设计对红外灵敏探测有重要意义.

The design of a novel low-background spectrometer based on lamellar grating interferometer (LGI) is presented. Reducing background noise helps to improve the spectrometer system detectivity for detectors operating under background limited performance (BLIP) regime, and then improve the signal to noise ratio (SNR) of spectrometer. The principle is that perfect mirrors do not emit blackbody radiation since their emissivity equals zero. Therefore, a lamellar grating interferometer based on a “cold” source and a “cold” detector becomes an extremely sensitive instrument because of the reduction of background radiation. Theoretical analysis shows that the system detectivity can be improved substantially with background radiation dropping. In ideal case, for a typical HgCdTe detector, the real BLIP detectivity obtained and corresponding SNR can be improved by three orders of magnitudes when background radiation is reduced from 300 K to 77 K. Besides, without cooling the interferometer, this configuration is more compact and easier-to-build compared with previously reported low-background Michelson spectrometer. This design has important significance for infrared sensitive detection.