高精度弓型光纤光栅微位移传感器

High-precision bow-shaped fiber Bragg grating micro-displacement sensors

为了测量控机床结构件、微加工工作台的微小变形量,设计了一种高精度弓型光纤布拉格光栅(FBG)微位移传感器。将光纤布拉格光栅的栅区部分粘贴在弓型上下壁处,当弓形件发生变形时,可测出上下壁的应变值,从而测得位移值并进行温度解耦。实验结果表明,在量程为1mm时,传感器的灵敏度为2.02pm/μm,线性相关系数为0.998 3,实验的迟滞误差为4.08%,重复性误差为4.08%。在温度补偿实验中可以看出,当温度上升1℃,波长漂移量不到1pm。类似于弓型结构衍生出一种半弓型结构的位移传感器。两类传感器相比,弓型传感器的温度灵敏度比半弓型传感器小0.001 5pm/μm,温度补偿效果更好;但半弓型传感器的线性度为0.4%,线性度比弓型传感器好。两种传感器均满足测量值稳定可靠、精度高、抗电磁干扰能力强,温度不敏感等要求。

In order to realize small deformation measurements of Numerical Control(NC)machine tool structures and micro-processing platforms,a high-precision optical fiber Bragg grating(FBG)micro-displacement-sensor based on a bow shape was designed.The grating region of the FBG was attached to the upper and lower walls of the bow.Hence,the strain value of the upper and lower walls could be measured while the bow was deformed,allowing displacement measurement and achieving temperature decoupling.Experimental results show that in the displacement range of 1 mm,the sensitivity by fitting a straight line is 2.02 pm/μm,the linearity is 2.92%,the linear correlation coefficient is 0.998 3,the hysteresis error of three groups is 4.08%,and the repeatability error of three groups is 4.08%.A temperature compensation test is presented in addition,showing a wavelength drift of less than 1 pm with a temperature increase of 1°C.Furthermore,a similar half bow structure was derived and compared with the previous bow type in terms of their performance.The comparison shows that the temperature compensation of the bow type is 0.001 5 pm/μm,which is smaller than that of the half bow type,while the latter has a better static calibration linearity of 0.4%.It satisfies the sensor requirements of stability,higher precision,as well as strong electromagnetic interference resistance and temperature insensitivity.