论文部分内容阅读
阐述了一种平面薄板结构的平面型光纤Bragg光栅(Fiber Bragg Grating,缩写为FBG)水听器探头的工作原理,从理论和实验上分析研究了该探头的结构灵敏度、频率响应特性以及加速度响应特性。平面圆形薄板采用不锈钢,尺寸为:直径15 mm、厚度0．15 mm,探头为圆柱型,尺寸为:直径17 mm、长20 mm。对于该尺寸结构的FBG水听器,探头静态灵敏度可达23 fm/Pa,比裸光栅增敏7300倍;谐振频率为6．5 kHz,而且幅频特性在100 Hz～5．5 kHz频率范围内较为平坦;低频段加速度响应灵敏度为:58～75(fm·s~2/m),在1 m/s~2加速度作用下其输出等效(2．52～3．26 Pa)压力作用下的输出。该结构的探头也便于多路复用组成水听器阵列。该平面结构不仅可以组成光纤FBG水听器探头,同样可以组成光纤光栅激光水听器探头。对薄板的几何尺寸进行适当的调整,可实现不同量程、不同带宽的水声压力测量。
The working principle of a flat fiber Bragg grating (FBG) hydrophone probe with a planar thin plate structure is described. The structure sensitivity, frequency response characteristics and acceleration response of the probe are analyzed theoretically and experimentally characteristic. The flat round sheet is stainless steel and measures 15 mm in diameter and 0.15 mm in thickness. The probe is cylindrical and measures 17 mm in diameter and 20 mm in length. For this size FBG hydrophone, the static sensitivity of the probe is up to 23 fm / Pa, which is 7300 times higher than that of the bare grating. The resonant frequency is 6.5 kHz and the amplitude-frequency characteristic is in the range of 100 Hz to 5.5 kHz The sensitivity of low-frequency acceleration is 58 ~ 75 (fm · s ~ 2 / m) and its output is equivalent (2.52 ~ 3.26 Pa) under 1 m / s ~ 2 acceleration Under the output. The structure of the probe is also easy to multiplex the hydrophone array. The planar structure can not only compose optical fiber FBG hydrophone probe, but also form fiber grating laser hydrophone probe. Proper adjustment of the plate geometry allows for the measurement of underwater acoustic pressure in different ranges and different bandwidths.