Multi-wave electromagnetic-acoustic sensing and imaging : physics and system

Abstract

Single-wave electromagnetic (EM) sensing and imaging has attracted tremendous research interest for many real-life applications, ranging from high-frequency optical imaging (e.g. confocal microscopy, coherence optical tomography), microwave imaging (e.g. Radar, THz imaging), to low-frequency magnetic imaging (e.g. MRI). On the other hand, single-wave acoustic sensing and imaging have also found many applications in Sonar system, medical ultrasound imaging, non-destructive testing (NDT), etc.. Unfortunately, these single-wave sensing and imaging techniques suffers from either low imaging contrast or spatial resolution due to the nature of single-wave diffusion and/or diffraction. In recent decades, multi-wave EM-Acoustic sensing and imaging have shown significant potential in biomedical applications by "listening to the sound of EM wave" based on photoacoustic/thermoacoustic effect, i.e. acoustic generation due to transient EM energy absorption and thermoelastic expansion. Bridging the beauty of the two worlds, multi-wave EM-Acoustic imaging could break through the diffusion and diffraction limit of EM wave by detecting the induced acoustic wave with 1000 times less scattering, enhancing the spatial resolution with deep penetration and simultaneously maintaining the high contrast/specificity of EM sensing and imaging. To further advance the multi-wave EM-Acoustic sensing and imaging techniques, this PhD thesis comprehensively investigates several novel aspects of this area, covering fundamental methods, biomedical applications and system implementations.