Session: Poster & Student Poster Session

Paper Number: 170866

170866 - Frequency Multiplexed Photothermal Correlation Tomography: Toward Three-Dimensional Thermal Tomography in Industrial Inspection 

Abstract: 

Infrared thermography has been widely applied in real-time industrial inspection of aerospace, energy management systems, engines and electric systems. However, two-dimensional imaging modality limits its development. Conventional thermal tomography techniques such as dynamic thermal tomography has low signal-to-noise ratio as they only rely on the time-domain signals. Advanced truncated-correlation photothermal coherence tomography techniques require a chirp-pulsed excitation and high frame-rate camera to ensure high lateral and depth resolution. Here, a technique named frequency multiplexed photothermal correlation tomography (FM-PCT) was developed to enable non-destructive and contactless cross-sectional imaging for manufactured material evaluation and characterization. By combining advantages of photothermal tomography and pulsed thermography, FM-PCT facilitates the generation of three-dimensional thermal images through temporal superposition (stacking) of two-dimensional images from sequential subsurface depths.  FM-PCT image processing involves pulsed excitation signals to which frequency delay and matched filtering techniques are applied. Major features of FM-PCT are high resolution three-dimensional tomographic imaging under low camera frame-rate conditions with self-correcting capability for diffusion (blurring) correction of subsurface images due to cross-correlation processing of individual frequencies in the Fourier decomposition spectrum of the excitation pulse. Furthermore, FM-PCT extends truncated-correlation photothermal coherence tomography from chirp and pulsed signals to more general linear heating sources. Lock-in thermography and X-ray computed tomography validation demonstrate that 3-D FM-PCT imaging accurately reveals subsurface discontinuities / defects in solids despite the diffusive nature of thermal-wave imaging.

Presenting Author: Pengfei Zhu Laval University

Presenting Author Biography: Pengfei Zhu received the B.Eng. degree in engineering mechanics from North University of China, Taiyuan, China, in 2019, and the M.Eng. degree in solid mechanics from Ningbo University, Ningbo, China, in 2022. He is currently working toward the Ph.D. degree in electrical engineering with Université Laval, Québec, Canada.
His research interests include non-destructive testing, infrared thermography, deep learning, terahertz time-domain spectroscopy, and photothermal coherence tomography.

Authors:

Pengfei Zhu Laval University
Rongbang Wang Harbin Institute of Technology
Koneswaran Sivagurunathan University of Toronto
Stefano Sfarra University of L'Aquila
Fabrizio Sarasini Sapienza University of Rome
Clemente Ibarra-Castanedo Laval University
Xavier Maldague Laval University
Hai Zhang Harbin Institute of Technology
Andreas Mandelis University of Toronto