Lock-in vibration retrieval based on high-speed full-field coherent imaging

Area of Science:

• Optics and Mechanics
• High-Speed Imaging
• Coherent Imaging

Background:

• High-speed cameras enable visualization of physical phenomena at fine temporal and spatial scales.
• Coherent imaging combined with high-speed imaging allows for optical path difference retrieval, applicable across various scientific fields.
• Achieving high performance and accuracy simultaneously at high frame rates remains a challenge, particularly for full-field vibrometry in mechanics.

Purpose of the Study:

• To demonstrate a coherent imaging approach for high-performance full-field structural vibration measurements.
• To address the limitations of applying high-speed imaging to full-field vibrometry in mechanics.
• To achieve high spatial and temporal density measurements in holographic measurements.

Main Methods:

• Development of a high-speed on-line digital holography method.
• Recording a short time sequence of holographic data.
• Validation through comparison with a scanning laser Doppler vibrometer and realistic simulations.

Main Results:

• The proposed coherent imaging approach yields state-of-the-art performance for full-field structural vibration measurements.
• Demonstrated capability for high spatial and temporal density holographic measurements.
• Error criteria confirm the measurement capability for amplitude and phase of structural deformations.

Conclusions:

• The developed method successfully enables high-speed, full-field structural vibration measurements.
• This approach overcomes previous limitations in applying high-speed imaging to mechanics.
• The technique provides accurate amplitude and phase information of structural deformations.