Space Science and Technology Department, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX, UK.
Opt Lett. 2011 Jun 1;36(11):1951-3. doi: 10.1364/OL.36.001951.
We demonstrate a widely tunable laser heterodyne radiometer operating in the thermal IR during an atmospheric observation campaign in the solar occultation viewing mode. An external cavity quantum cascade laser tunable within a range of 1120 to 1238 cm(-1) is used as the local oscillator (LO) of the instrument. Ultra-high-resolution (60 MHz or 0.002 cm(-1) transmission spectroscopy of several atmospheric species (water vapor, ozone, nitrous oxide, methane, and dichlorodifluoromethane) has been demonstrated within four precisely selected molecule-specific narrow spectral windows (∼1 cm(-1). Atmospheric transmission lines within each selected window were fully resolved through mode-hop-free continuous tuning of the LO frequency. Comparison measurements were made simultaneously with a high-resolution Fourier transform spectrometer to demonstrate the advantages of the laser heterodyne system for atmospheric sounding at high spectral and spatial resolutions.
我们展示了一种在热红外波段工作的宽调谐激光外差辐射计，该辐射计在太阳掩星观测模式下进行大气观测。该仪器使用可在 1120 至 1238cm(-1)范围内调谐的外腔量子级联激光器作为本振（LO）。已经在四个精确选择的分子特定窄光谱窗口（约 1cm(-1)内演示了几种大气物质（水蒸气、臭氧、氧化亚氮、甲烷和二氯二氟甲烷）的超高分辨率（60MHz 或 0.002cm(-1)）透射光谱。通过 LO 频率的无跳模连续调谐，完全分辨出每个所选窗口内的大气传输线。同时进行了比较测量，使用高分辨率傅里叶变换光谱仪演示了激光外差系统在高光谱和空间分辨率下进行大气探测的优势。
