Meta atoms for sound wave transmission and imaging
Prof. Oliver B. Wright
Hokkaido University, Sapporo, JAPAN
Abstract: We present a scanning near-field acoustic imaging technique based on a zero-mass meta-atom that exploits extraordinary acoustic transmission. The probe converts evanescent acoustic fields into propagating waves inside an airfilled waveguide, with object proximity sensed via changes in the acoustic reflection coefficient arising from the sonic Drexhage effect. By operating at the zero-effective-mass condition, the system achieves laterally isotropic, non-contact imaging with extreme subwavelength resolution. Experiments supported by theory and numerical simulations demonstrate lateral resolutions of approximately λ/20 and depth resolutions approaching λ/650 at kilohertz frequencies. This approach provides a simple, lensless platform for high-resolution acoustic near-field imaging and topography.