| Laser-induced acoustic wave technology is a composite technology which has the advantages of both laser and sonic wave. Since this technology is non-contacting, high-accuracy and more reliable, it has been widely applied in a variety of fields, such as NDT, antithrombotic therapy, gas detection, etc.Besides, laser-induced acoustic wave technology also has a promising future in the field of underwater communication. Because electromagnetic wave attenuates greatly in the water, the traditional electromagnetic tele-communication on land cannot work. Furthermore, the blue-green laser system for underwater communications in the recent years has its own inherent limits, since it only can be applied in the clear water area, as a result, only few hundred meters of communication distance has been realized. In contrast, the opto-acoustic communication technology can provide a long communication distance as the infrared laser can transmit nearly lossless on the atmospheric window, and likewise, low-frequency sonic wave can realize a long communication distance in the underwater too.For the opto-acoustic communication system, firstly, we analyze the regime of laser-generated acoustic wave for both solid and liquid. Secondly, we study the characteristics of laser-generated acoustic wave form and frequency spectrum. Lastly, we investigate the relationship between BER (Bit Error Rate) and peak to average ratio (P/A ratio) at different bit-rates and the BER curves are presented, while a simple pre-coding method is used.Moreover, we also analyze laser ultrasound technology for the thickness measurements of steel plates. The PZT (Piezoe-lectric Transducer) detecting method is put forward and the measurement results are also present. |
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