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三、光纤传感技术(续) 3.速度、流量传感器 (1)激光多普勒测速传感器 光纤型激光多普勒测速传感器与传统激光测速方法的最大不同是激光束以及运动微粒散射信号光的传输与耦合皆通过光纤实现。这样就较好地解决了光路准直问题,同时也提高了抗光路干扰的能力,使这种技术的应用范围大大扩展。 光纤激光多普勒测速传感器系统如图1所示,它是把光纤探头以角度θ插入管道中,由光纤梢端发出的激光被运动流体微粒散射,产生多普勒位移的散射光信号,再由同一光纤耦合回传,并与原信号光重迭产生差拍。
3. Fiber Optic Sensing Technology (Cont.) 3. Velocity and Flow Sensor (1) Laser Doppler Velocimetry Sensor The biggest difference between the fiber laser Doppler velocimetry sensor and the traditional laser velocimetry method is that the laser beam and the moving particles scatter the signal light Transmission and coupling are achieved through optical fiber. In this way, the problem of collimation of the optical path is solved well, and the ability of intercepting the optical path is also improved, so that the application scope of the technique is greatly expanded. Fiber laser Doppler velocimetry sensor system shown in Figure 1, which is the optical fiber probe inserted into the pipe at an angle θ, the laser emitted by the fiber tip is scattered by the moving fluid particles to produce Doppler-shifted scattered light signal, and then Coupled back by the same fiber, and overlap with the original signal beat.