单光场时栅位移传感器散射角误差分析及优化

Analysis and Optimization of Scattering Angle Error of Single Light Field Time Grating Displacement Sensor

光场式时栅传感器采用光强调制的方式解决光栅对制造工艺的依赖,但提高了对光源出光特性的要求。通过对测量原理的分析,建立了单光源散射二维误差模型,分析了光源散射对电行波信号幅值和相位的影响,并通过仿真分析得出光源散射对测量的影响主要为一次和二次谐波误差成分,与未优化光源测量的主要谐波误差成分相吻合。提出一种光线空间约束的优化方法,采用切面迭代法设计准直透镜减小光源发散角,仿真结果表明所设计的光源发光半角从±60°降低到±10°。搭建实验平台进行验证,结果表明:在栅距0.2 mm的单周期测量范围内,与未优化光源对比,添加准直透镜的测量误差从±5.6μm减少到±1μm,其中一次、二次谐波误差成分得到明显抑制,100 mm范围内的长周期测量误差为±8μm。实验结果验证了散射角误差模型的正确性和准直透镜抑制效果的可行性。

Light-field time-grating sensors adopt light intensity modulation method to solve the dependence of the grating on the manufacturing process, but it improves the requirements for the light emission characteristics of the light source.Through the analysis of the measure principle, a two-dimensional error model of single light source scattering was established, and the influence of light source scattering on the amplitude and phase of the electric traveling wave signal was analyzed.The simulation analysis shows that the main influence on the measurement is the first and second harmonic error components, which is consistent with the main harmonic error components of the light source measurement not optimized.The optimization method for light space constraints was proposed, and the tangent surface iteration method was used to design the collimating lens to reduce the divergence angle of the light source, and simulation results show that the half-angle of the light source is reduced from ±60° to ±10°.The experimental platform was built to verify, which shows that in the single-period measurement range of 0.2 mm grating period, compared with not optimized light source, the measurement error with the collimating lens is reduced from ±5.6 μm to ±1 μm.Among them, the first and second error components are obviously suppressed, and the long period measurement error within the range of 100 mm is ±8 μm. Experimental results verify the correctness of the scattering angle error model and the feasibility of the collimating lens suppression effect.