• Optics and Precision Engineering
  • Vol. 26, Issue 12, 2909 (2018)
TANG Yuan-he1,*, WANG Hao-xuan1, LIU Qing-song2, LI Cun-xia1, and YU Tao2
Author Affiliations
  • 1[in Chinese]
  • 2[in Chinese]
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    DOI: 10.3788/ope.20182612.2909 Cite this Article
    TANG Yuan-he, WANG Hao-xuan, LIU Qing-song, LI Cun-xia, YU Tao. Forward measurement of submarine gas hydrates by active remote sensing technology[J]. Optics and Precision Engineering, 2018, 26(12): 2909 Copy Citation Text show less

    Abstract

    In this paper, an optical imaging interferometry system was proposed for the accurate detection of the temperature, pressure, and concentration of gas hydrates. As part of this system, laser light with a wavelength of 1.65 μm, was transmitted across the sea surface through a fiber to excite gas hydrates on the sea bed. Ten spectral lines close to the 1.65 μm waves emitted by CH4 were collected and transmitted to the sea surface through another fiber. Five image interference fringes for CH4 were obtained on a Charge-Coupled Device (CCD) camera. Using the "rotation line temperature measurement method" and the Lorentzian line profile, and by selecting the gray values of two adjacent interference fringes, the temperature, pressure, and concentration of the CH4 gas hydrates on the sea bed could be obtained. The forward results of the imaging interferogram for CH4 show that the electron count on the CCD is 1.68×105, much larger than which results in the noise value of 400e. The maximum signal-to-noise ratio of the system is 291. The narrowband interference filter could distinguish 10 spectral lines in the waves emitted by CH4 within the 16° field of view. The measuring precision of the CH4 temperature and concentration values are 1 K and 3%, respectively. This study shows that an imaging interference system can be used in the remote sensing of seabed gas hydrates.
    TANG Yuan-he, WANG Hao-xuan, LIU Qing-song, LI Cun-xia, YU Tao. Forward measurement of submarine gas hydrates by active remote sensing technology[J]. Optics and Precision Engineering, 2018, 26(12): 2909
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