Development of Cryogenic Far-Infrared Fourier Transform Spectrometer with High Spectral Resolution

远红外傅里叶变换光谱仪应在低温下工作，以避免其自身的热辐射。远红外天文学最好的方法是在没有大气吸收和发射的空间进行观测。本研究的目标是开发在这些异常条件下具有高光谱分辨率的傅立叶变换光谱仪。由于傅里叶变换光谱仪是基于双光束干涉仪，因此需要精确的位移传感器来参考光程差。远红外傅立叶变换光谱仪的位移传感器需要在低温下工作。例如，位移传感器的要求规格是总位移40毫米，精度为几微米。为了达到这一要求，我们采用了带干涉扫描头的光学标度。这种规模的商品级，当然不能在低温下工作。我们对传感器头模块的部分进行了修改，并将传感器芯片替换为低温部件。最后，我们开发了40毫米位移的低温位移传感器，精度为1微米。我们可以用我们的傅立叶变换光谱仪和这个位移传感器在低温下拍摄干涉图。本研究为构建低温远红外傅立叶变换光谱仪奠定了基础技术。

Far-Infrared Fourier transform spectrometer should be operated at cryogenic temperature to avoid the thermal emission from itself. And the best way for far-infrared astronomy is the observation in space where is free from the atmospheric absorptions and emissions. The goal of this research is to develop the Fourier transform spectrometer with high spectral resolution under these unusual conditions.Since Fourier transform spectrometer is based on two beams interferometer, the precise displacement sensor is required to refer optical path difference. The displacement sensor for far-infrared Fourier transform spectrometer should be worked at cryogenic temperature. For example, required specification of a displacement sensor is 40 mm total displacement with a few micrometers accuracy. To achieve this requirement we adopt the optical scale with interferential scanning head. The commercial grade of this type of scale, of course, does not work under cryogenic temperature. We modify the part of the sensor head module and replace the sensor chips with cryogenic parts. Finally, we have developed the cryogenic displacement sensor for 40 mm displacement with 1 micrometer accuracy.We can take interferograms using our Fourier transform spectrometer with this displacement sensor at cryogenic temperature. The fundamental techniques to construct the cryogenic far-infrared Fourier transform spectrometer are established through this research.