High-resolution, full-field visualization of mechanical vibrations by simultaneous phase-shifting interferometry

Mechanical vibration analysis is critical for diagnosing structural integrity, optimizing performance, and non-destructive testing in various fields, such as aerospace, automotive, and micro-electromechanical systems. Conventional nondestructive techniques, such as laser Doppler vibrometry or scanning-based methods, often suffer from limited spatial resolution, time-consuming data acquisition, or an inability to capture full-field dynamic behavior. Here we present high-resolution, full-field visualization of mechanical vibrations by using an advanced simultaneous phase-shifting interferometry (SPSI) and temporal Fourier analysis to overcome these limitations. The developed SPSI enables wavefront reconstruction of high-speed vibrations based on single-shot phase-shifting interferometry, allowing high-resolution mapping of dynamic mechanical deformation across the field of view. Then the vibration frequency map can be obtained by applying Fourier-transform analysis to the temporal phase values for further vibration analysis. The feasibility and advantages of the proposed method are demonstrated experimentally by identifying the vibration frequencies of a metal plate, which match the setting frequencies of the excitations from a piezo actuator attached to the metal plate. The current design provides high spatial resolution of 18.5 μm with the detection area of 9 mm×6 mm. This work establishes SPSI as a powerful metrology tool for high-resolution vibration measurement, providing engineers and researchers with unprecedented insight into dynamic mechanical behavior.