High-Resolution Atmospheric-Transmission Measurement with a Laser Heterodyne Radiometer
WU Qing-chuan1, 2, HUANG Yin-bo1, TAN Tu1, CAO Zhen-song1*, LIU Qiang1, GAO Xiao-ming1, RAO Rui-zhong1
1. Key Laboratory of Atmospheric Composition and Radiation, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
2. Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China
Abstract：Laser heterodyne technology is a highly sensitive laser spectroscopy technique which can be integrated. It has the potential to develop a compact ground or satellite based radiometer for Earth observation and astronomy. Based on the laser heterodyne technology, a set of high resolution laser heterodyne detection system was established together with a solar tracker. The spectral resolution of the system is about 0.006 cm-1. Sunlight is superimposed with infrared laser light in a nonlinear detector. The signals pass through an electronics filter and a square-law detector, then the high-resolution heterodyne signal is extracted. In terms of the field measurement, Langley-Plot Calibration method was used to calibrate the system first, then total atmosphere transmittance of mid-infrared was measured. The calibration constant and corresponding to the atmospheric total optical thickness were presented. According to the comparison between the results of heterodyne measurement system and that of software MORTRAN5.0 calculation, good agreement was obtained. It is shown that the system has high spectral resolution which can be applied to atmospheric transmittance measurement. Besides, the system also shows potential applications in atmospheric sciences, astronomy, laser propagation through the atmosphere and other areas.
Key words：Spectroscopy; Laser heterodyne; Total atmospheric transmittance; Langley-plot
