大剪切电子散斑干涉的载频调制与位移场测量

将电子散斑干涉场的载波调制引入到大剪切电子散斑干涉中,通过对参考物的微小偏转引入载波条纹;利用傅里叶变换法,解调出了变形场的相位,从而实现了物体变形场的精确测量。讨论了大剪切载频的调制机理,理论分析表明,调制条纹的空间频率与参考面偏转的角度成正比;因此,控制参考面的偏转角度可实现不同位移量系统的调制。利用中心加载周边固定圆盘进行了典型实验,实验结果证明在大剪切电子散斑干涉技术中可以通过参考面的旋转高质量地实现电子散斑干涉条纹的调制,求解位移场。该系统具有系统简单,不需要专门引入参考光,条纹质量好等优点。该技术可扩展电子散斑干涉的应用范围,有一定的实际应用价值。

Carrier Modulation for Large-Shearing Electronic Speckle Patterns Interferometry and Displacement Measurement

The digital speckle fringe pattern is modulated by spatial carrier in large-shearing electronic speckle pattern interferometry (ESPI). The carrier is introduced by rotating the reference plane a small angle. When Fourier transform is used to demodulate the modulated fringe pattern, the phase of deformation is calculated and furthermore the deformation is measured accurately. The principle of carrier modulation in large-shearing ESPI is discussed. The theoretical analysis shows that the frequency of carrier used for modulation is proportional to the rotational angles of reference plane. Therefore, the fringe patterns with different displacements can be modulated easily by rotating reference plane different angles. A typical experiment using a centrally loaded clamped circular plate is completed. The experimental results prove that the carrier introduced by rotating the reference plane in large-shearing ESPI can modulate speckle pattern very well and the displacement fields can be obtained effectively. The optical modulation system has some advantages: the system is simple and has no special reference beam for interference. And the carrier pattern has higher fringe visibility. This technique presented here would extend the application range of ESPI and have some applications in practices.