Lyu Chengang, Liu Ying, Wu Chuang
Appl Opt. 2016 Jul 1;55(19):5057-62. doi: 10.1364/AO.55.005057.
A dual-frequency ultrasound measurement system based on a distributed Bragg reflector (DBR) fiber laser sensor in a liquid medium was presented. To compare the dual-frequency measurement performance of a DBR fiber laser acoustic sensor with that of a piezoelectric (PZT) ultrasound sensor, two experiments were performed. First, we fixed the driving frequencies of two ultrasound signals at 3 and 5 MHz, and decreased the driving voltage from 15 to 3 V. The outputs of the DBR acoustic sensor show flat-balanced response to dual-frequencies, compared with the PZT acoustic sensor whose response to one of the dual-frequency signals (5 MHz in this paper) has been covered by noise at low acoustic pressure. Then we increased the acoustic pressure by fixing the driving voltage at 20 V, and changed the frequency spacing between the two ultrasound signals. By analyzing the frequency response, sensitivity, signal-to-noise ratio, and noise equivalent pressure of two acoustic sensors under different frequencies, we found that the response of the DBR sensor to wideband dual-frequency is stable, while the response of the PZT sensor deteriorates sharply with increasing frequency spacing. The results demonstrate that the DBR fiber laser sensor performs better for wide bandwidth dual-frequency ultrasound measurements.
提出了一种基于分布式布拉格反射器（DBR）光纤激光传感器的双频超声测量系统，该系统用于液体介质中。为了比较DBR光纤激光声学传感器与压电（PZT）超声传感器的双频测量性能，进行了两个实验。首先，将两个超声信号的驱动频率固定在3 MHz和5 MHz，并将驱动电压从15 V降低到3 V。与PZT声学传感器相比，DBR声学传感器的输出对双频呈现出平坦平衡的响应，而PZT声学传感器对双频信号之一（本文中为5 MHz）的响应在低声压下已被噪声覆盖。然后，将驱动电压固定在20 V以增加声压，并改变两个超声信号之间的频率间隔。通过分析两个声学传感器在不同频率下的频率响应、灵敏度、信噪比和噪声等效压力，我们发现DBR传感器对宽带双频的响应是稳定的，而PZT传感器的响应随着频率间隔的增加而急剧恶化。结果表明，DBR光纤激光传感器在宽带双频超声测量方面表现更好。
