Multi-target CW interferometric acoustic measurements on a single optical beam

Area of Science:

• Optics and Photonics
• Acoustics and Vibration Analysis
• Metrology

Background:

• Dynamic phase measurement of acoustic signals is crucial for various scientific and industrial applications.
• Existing interferometric systems often face challenges in simultaneously measuring multiple targets and mitigating cross-talk.

Purpose of the Study:

• To develop a free-space, continuous-wave laser interferometric system for multi-target dynamic phase measurement.
• To achieve high displacement sensitivity and resolution for acoustic signals across the audio band.

Main Methods:

• Utilized Digitally-enhanced Heterodyne Interferometry (DEHI).
• Implemented range gating to isolate acoustic signals from multiple in-line reflections.
• Developed techniques to suppress coherent cross-talk between measurement points.

Main Results:

• Demonstrated sub-nanometer displacement sensitivity for individual reflection surfaces across the audio band.
• Achieved 1.2 m resolution between successive surfaces.
• Suppressed signals outside the 1.2 m range-gate by over 30 dB, ensuring high-fidelity independent acoustic measurements.

Conclusions:

• The developed laser interferometric system enables simultaneous, high-fidelity dynamic phase measurements of multiple acoustic targets.
• The system offers excellent displacement sensitivity and range resolution, overcoming limitations of previous methods.