Misalignment analysis in a phase-stepping electronic speckle pattern interferometer for full-field displacement measurement

摘要

A compact and stable phase-stepping four-channels one-beam interferometer for full field displacement measurement in static and "real time" operation mode can be built through incorporation of a four-exposure reflection holographic optical element, which reconstructs four reference planes under illumination with two pairs of laser diodes positioned in the horizontal and the vertical planes. Such a multi-channel system is prone to misalignment errors and their estimation is crucial for its successful operation. The present work gives analysis of the error due to misalignment in illumination directions of the laser sources for the case of the out-of-plane (normal) displacements under double symmetrical illumination. First, analysis of the misalignment error observed in the experimental data is provided. Second, computer simulation of the system was made for estimation of the out-of-plane (normal) component of the displacement vector at each point of the tested object, and quantitative analysis of the errors caused by the misalignment was performed.