Innovative prototype design and benchmarking for vibration displacement measurement ranging from sub-micron to micron via laser self-mixing interference

Vibration displacement measurement is crucial in disciplines such as structural engineering, mechanical systems analysis, and condition monitoring. Laser vibrometers are commonly employed for assessing object vibration characteristics without physical contact. However, these devices typically require extra optical components or variable attenuators to manage optical power, resulting in increased cost and system complexity. This limitation impedes their broad application, particularly in constrained environments. In this study, a novel self-mixing prototype is introduced for measuring speaker vibration displacement via laser self-mixing interference. By utilizing a retro-reflective tape with prism reflection to enhance the self-mixing signal, the prototype achieves accurate vibration displacement measurement across various amplitudes and frequencies. The self-mixing prototype demonstrate the capability to deliver precise measurement ranging from 630 nm to 100.170 µm, with an investigation into the impact of laser wavelength on vibration displacement measurement. To assess its efficacy, a 3D scanning vibrometer serves as a benchmark, revealing an accuracy rate of up to 98.06 % in vibration displacement measurement for the self-mixing prototype. This study introduces a cost-effective and compact alternative that provides accurate vibration displacement measurement, rendering it suitable for applications such as vibration analysis, rail monitoring, and quality control. By streamlining the measurement process and reducing complexity, the self-mixing prototype emerges as a promising solution for industries requiring precise vibration measurement.