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Proceedings Paper

Fast photomultiplier tube gating system for underwater laser detector
Author(s): Xuanhua Lei; Kecheng Yang; Jionghui Rao; Xiaohui Zhang; Min Xia; Yi Zheng; Wei Li
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Paper Abstract

Laser will attenuate during its propagation in water and also be backward scattered by water when it is used to detect bubbles in the ocean. Meanwhile backward scattering intensity of the bubbles is feeble, its dynamic range reaches to the order of 6, which saturates PMT and its post-treatment circuit. Timely gating system is used to solve the problem. The system contains pulsed laser and gating PMT receiver. The wavelength of the laser is 532nm, with pulse width of several nanometers. Its operational delay is matched with the time period between laser traveling forward and back after scattered by the target. By doing this, the light scattered by other object is eliminated, dynamic range of the signal reduces, and consequently SNR increases. In order to avoid Signal Induced Noise(SIN), we choose PMT R1333 having no HA coating. TTL logical level, which is used as gating signal, controls the first dynode voltage of PMT to implement gating. Gating speed is about 100ns, of which the width is tunable. By carefully designing the electronic system, SNR is eliminated to a level as low as possible, and the output signal of PMT is fast integrated in order to reduce the influences of signal induced by opening the gate.

Paper Details

Date Published: 29 January 2007
PDF: 6 pages
Proc. SPIE 6279, 27th International Congress on High-Speed Photography and Photonics, 627948 (29 January 2007); doi: 10.1117/12.725375
Show Author Affiliations
Xuanhua Lei, Huazhong Univ. of Science and Technology (China)
Naval Univ. of Engineering Wuhan (China)
Kecheng Yang, Huazhong Univ. of Science and Technology (China)
Jionghui Rao, Huazhong Univ. of Science and Technology (China)
Naval Univ. of Engineering Wuhan (China)
Xiaohui Zhang, Naval Univ. of Engineering Wuhan (China)
Min Xia, Huazhong Univ. of Science and Technology (China)
Yi Zheng, Huazhong Univ. of Science and Technology (China)
Wei Li, Huazhong Univ. of Science and Technology (China)


Published in SPIE Proceedings Vol. 6279:
27th International Congress on High-Speed Photography and Photonics

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