Integrated design of three-dimensional continuous displacement measurement with temporal speckle interferometry

The three-dimensional electronic speckle pattern interferometry (3D ESPI) is widely used in many fields due to its ascendancy of non-contact, high precision, high sensitivity and full-field measurement. In order to realize the non-contact dynamic full-field 3D measurement, a compact and complete 3D measurement system was designed and set up. Three independent lasers were replaced by a single multi-wavelength fibre coupling laser to produce the speckle pattern interferograms of out-of-plane and in-plane, which could be captured and processed by only one charge coupled device (CCD) camera. The entire measurement system adopted cage construction with high flexibility and stability. The phase unwrapping algorithm based on the wavelet transform was programmed to realize the complete extraction of 3D displacement information on the measured object. The experimental results show that this measurement system can obtain the 3D displacement of the measured object. The 3D displacement values in the experiments are 17.68 μm, 36.23 μm and 13.85 μm, compared with the actual displacement values of 18.1 μm, 36.4 μm and 14.0 μm, the absolute errors are 0.42 μm, 0.17 μm and 0.15 μm, respectively,and the relative errors are 2.3%, 0.5% and 1.1%.