主动遥感探测海底可燃冰的正演研究

Forward measurement of submarine gas hydrates by active remote sensing technology

本文提出利用光学成像干涉技术主动遥感探测可燃冰的温度、压强、浓度物理量。通过光纤将海面上波长为1.65μm的激光传输到海底,激发海底可燃冰,将CH4发射的1.65μm附近相距很近的10条谱线用光纤收集传回到海面上,经过成像干涉系统,在CCD相机上得到5条成像干涉条纹,选择两条相邻干涉条纹的灰度值,利用"转动谱线测温法"和洛伦兹线型即可获得海底可燃冰CH4的温度、压强、浓度等参量。实验得出CH4的正演成像干涉图,并得到CCD上的电子计数1.68×105远远大于拟用CCD噪声400e,系统的最大信噪比为291,窄带干涉滤光片可在16°视场内区分CH4的10条目标谱线,CH4的温度和浓度探测精度分别为1K和3%。研究表明,该成像干涉系统可用于遥感探测海底可燃冰。

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 1.65μm,was transmitted across the sea surface through a fiber to excite gas hydrates on the sea bed.Ten spectral lines close to the 1.65μm waves emitted by CH 4 were collected and transmitted to the sea surface through another fiber.Five image interference fringes for CH 4 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 CH 4 gas hydrates on the sea bed could be obtained.The forward results of the imaging interferogram for CH 4 show that the electron count on the CCD is 1.68×10^5,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 CH 4 within the 16°field of view.The measuring precision of the CH 4 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.