Multipoint Energy-Balanced Laser-Ultrasonic Transducer Based on a Thin-Cladding Fiber

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Acoustics

Background:

• Laser-ultrasonic (LU) techniques are crucial for non-destructive testing (NDT).
• Conventional LU transducers face limitations in signal amplitude and efficiency.
• Novel fiber structures are needed to enhance LU system performance.

Purpose of the Study:

• To propose and demonstrate a novel multipoint transducer system using single-mode-multimode-thin-cladding (SMTC) fiber.
• To investigate the factors influencing coupling efficiency in the SMTC structure.
• To evaluate the performance of the proposed system with different photoacoustic materials.

Main Methods:

• Fabrication of a novel SMTC fiber-based transducer.
• Simulation analysis of MMF length and TCF diameter effects on coupling efficiency.
• Experimental comparison of graphite-epoxy resin and CSNP-PDMS composite materials.
• Development of a three-point energy-balanced LU transducer system.

Main Results:

• The SMTC transducer achieved 2-3 fold higher signal amplitudes than conventional LU transducers.
• Coupling efficiency was precisely controlled by adjusting MMF length.
• Optimal CSNP thickness was determined experimentally.
• CSNP-PDMS composite showed higher photoacoustic conversion efficiency than graphite-epoxy resin.

Conclusions:

• The SMTC fiber structure offers a safe and efficient method for generating high-amplitude ultrasonic signals.
• The proposed multipoint LU transducer system demonstrates improved energy conversion efficiency.
• The system holds significant potential for advanced NDT applications, particularly with CSNP-based materials.