使用激光在晶体表面激发的声表面波, 尝试根据叉指换能器的逆压电效应来探测激光, 从而实现声场的变化反演激光照射情况.在讨论激光照射对铌酸锂晶体中声表面波传播特性造成的影响时, 建立了点状激光照射的热弹理论模型.首先排除环境温度整体变化的影响, 证明了光对声场的影响和照射晶体内部温度梯度的变化有关;然后设计13 MHz为中心频率的叉指换能器, 从模拟与实验效果对比来看, 由激光激发的声表面波影响了原叉指激发波的频率, 13 MHz及周围频率时的声压变化明显, 中心频率迁移到15 MHz, 声压值波动衰减, 从而反演激光的存在;通过理论和实验分析证明了声场检测激光的可行性, 可以开拓性地将叉指换能器作为特殊传感器, 可用于激光窃听等特殊场合.%In order to detect the laser according to the inverse piezoelectric effect of the interdigital transducer, using the surface acoustic wave excited by the laser on the crystal surface, so as to realize the variation of the sound field to reflect the laser irradiation. A thermoelastic theoretical model for point-like laser irradiation was built, which proved that the influence of the light on the sound field was related to the change of the internal temperature gradient of the irradiated crystal after ruling out the impact of the overall change in ambient temperature. Then an interdigital transducer centered at 13 MHz was designed. According to the simulation and experimental results, the surface acoustic wave caused by laser excitation affects the frequency of the excitation wave of the original transducers.The sound pressure change at 13 MHz and surrounding frequency is obvious. And the center frequency moves to15 MHz after laser irradiation. So the presence of the laser can be mapped. The theoretical and experimental analysis proves the feasibility of detecting laser by the sound field. The interdigital transducer is creatively regarded as a special sensor and can be used for special occasions such as laser eavesdropping.
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