Research on ship wake detection by optical method of small angle forward scattering

Donghua Zhu; Jionghui Rao; Xiaohui Zhang; ChunSheng Sun

doi:10.1117/12.790812

22 February 2008 Research on ship wake detection by optical method of small angle forward scattering

Donghua Zhu, Jionghui Rao, Xiaohui Zhang, ChunSheng Sun

Proceedings Volume 6622, International Symposium on Photoelectronic Detection and Imaging 2007: Laser, Ultraviolet, and Terahertz Technology; 66220X (2008) https://doi.org/10.1117/12.790812
Event: International Symposium on Photoelectronic Detection and Imaging: Technology and Applications 2007, 2007, Beijing, China

Abstract

A ship wake in the ocean contains lots of microsize air bubbles with diameter of 10μm~200μm. When a beam of light propagates through the ship wake, it leads to attenuation of the light energy and change of its spatial distribution due to absorption and scattering caused by ocean water and bubble mass together, but they don't share the same scattering mechanism, leaving absorption out of account. Scattering from micro bubbles can usually be explained by Mie scattering theory. In this paper, a method based on optical scattering theory is proposed for detecting the target of ship wake in the ocean, and an experimental system is built up according to the Lambert-Beer law. In the experiment, a semiconductor laser with wavelength about 532nm was employed as the light source, an experimental device which modeled the target of a ship wake to generate bubble mass in water, and a high-speed PIN photodiode as the detector. Besides, the optical receiving system included a set of optical lens and apertures, which were employed to limit the field of view(FOV) of the receiver detector. After measurement of the small angle forward scattering rays scattered from bubble mass with a small FOV, the target signals was got and processed. Then adjustments were made to the optical receiving system and experiments were implemented with varying the FOV to find out the influence of FOV on target signal SNR and obtain the optimum FOV. The results showed that adjusting the FOV according to different microbubble size density could improve SNR.

Citation Download Citation

Donghua Zhu, Jionghui Rao, Xiaohui Zhang, and ChunSheng Sun "Research on ship wake detection by optical method of small angle forward scattering", Proc. SPIE 6622, International Symposium on Photoelectronic Detection and Imaging 2007: Laser, Ultraviolet, and Terahertz Technology, 66220X (22 February 2008); https://doi.org/10.1117/12.790812

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