双光栅测微弱振动实验中光拍成像质量的改进

IMPROVEMENT OF OPTICAL BEAT SIGNALIN THE EXPERIMENT OF MEASURING WEAK VIBRATION WITH TWO GRATINGS

文章针对大学物理实验'双光栅测微弱振动'中光拍信号容易出现'毛刺'和'包络'的问题开展了实验研究。针对'毛刺'信号,分析发现是由于众平行光束叠加后,产生的拍频含有丰富的高次谐波,表现在波形上是'毛刺'。利用Matlab的GUI程序仿真模拟进行验证,然后根据分析的结果,得出将光栅间距控制在一定范围内可以解决'毛刺'。针对'包络'问题,通过理论分析找到其产生的原因是单振动光栅的衍射光边缘的强度变化,进一步分析发现是光栅振动同时伴随的转动造成的。在振动光栅后加光阑抑制衍射光的边缘部分,从而消除'包络'。

In this paper,the experimental research on the problem of'burr'and'envelope'in the optical slap signal of'double grating measurement weak vibration'in university physics experiment is carried out.For the'burr'signal,it is found that the beat frequency generated by the superposition of multiple parallel beams contains abundant high-order harmonics,which is reflected in the'burr'waveform.Simulations are performed with the GUI program of MATLAB.According to the analysis results,it is concluded that the'burr'can be solved by controlling the grating spacing within a certain range.For the'envelope'problem,the reason is found theoretically as the change the intensity change of the diffraction edge of single vibration grating.Further analysis revealed that the grating vibration is accompanied by the accompanying rotation.The'envelope'is eliminated by adding an aperture after the vibration grating to suppress the edge of the diffracted light.