为了满足压力测量中的高灵敏度、高分辨率、高可靠性等要求,本文提出了一种基于调频连续波激光干涉解调原理的高精度膜片式珐珀腔光纤压力传感器。首先推导了基于该原理的压力测量模型,然后搭建了一套测量装置,通过气泵向SUS631不锈钢膜片组成的密封腔连续给压,得出气压在0~600 kPa范围内变化时膜片中心(即珐珀腔腔长变化量)随气压变化的特性曲线;之后,测试25 ℃环境条件下不同压力测量值的稳定性,讨论引起腔长变化量漂移的原因;最后,在消除系统误差后得出了压力测量的分辨率。结果表明:该传感器的灵敏度为286.55 nm/kPa,分辨率为0.287 nm/Pa,压力传感器的测量随机误差呈正态分布。该调频连续波光纤压力传感器可以进行高灵敏度、高分辨率和高稳定性测量。

To meet the requirements of high sensitivity, resolution, and reliability in pressure measurements, in this paper, we proposed a high-precision optical fiber pressure sensor with a diaphragm-type Fabry-Perot (F-P) cavity based on the demodulation principle of frequency-modulated continuous wave (FMCW) laser interference. Firstly, a pressure measurement model based on this principle was deduced. Secondly, a pressure measuring device was developed and subsequently the sealed cavity formed by the SUS631 stainless steel diaphragm was continuously inflated through an air pump to collect the characteristic curve of the central deformation of the SUS631 stainless steel diaphragm (which is the amount of change in the F-P cavity length) with the air pressure when the air pressure changed in the range of 0--600 kPa. Furthermore, the cavity change of F-P cavity was measured at 25 ℃ and different pressures and the causes inducing the drift of the cavity change were discussed. Finally, the resolution of pressure measurements without the system error was acquired. The results show that the FMCW pressure sensor has a sensitivity of 286.55 nm/kPa and a resolution of 0.287 nm/Pa and its random measurement error displays a normal distribution. The above analyses verify that the proposed FMCW optical fiber pressure sensor can perform measurements with high sensitivity, resolution, and stability.