Three-dimensional displacement measurement via fusion of holographic speckle interferometry and event-based vision

Traditional three-dimensional digital speckle interferometry generally relies on synchronized multi-beam, multi-wavelength, or multi-camera configurations to obtain three-dimensional displacement vectors, which often leads to complex optical setups, dimensional coupling, and difficulties in synchronizing dynamic processes. To overcome these limitations, this paper proposes a three-dimensional dynamic displacement-field measurement method that integrates digital holographic speckle interferometry with event vision. First, holographic interference patterns are recorded by an industrial camera combined with a spatial phase-shifting technique, enabling high-precision phase reconstruction of out-of-plane micro-deformation on the object surface. Then, an event camera is introduced to asynchronously capture speckle-intensity variations on the surface for in-plane displacement measurement. The event stream is temporally accumulated, and a block-matching algorithm is used for displacement estimation. Finally, the highly sensitive out-of-plane phase information is fused with the in-plane displacement data to reconstruct the complete three-dimensional displacement field. Experimental results show that the proposed digital holographic speckle interferometry–event vision fusion system can stably measure the three-dimensional displacement field of circular thin plates. The minimum RMSE values reach 0.47 μm for out-of-plane displacement, 0.18 μm for in-plane displacement, and 0.13 μm for the fused three-dimensional displacement field. The proposed method generally satisfies the requirements of high precision, good stability, and strong anti-interference capability in three-dimensional micro-deformation measurement.