Far-field acoustic subwavelength imaging and edge detection

The resolution of far-field acoustic imaging is limited due to the loss of the evanescent field that carries subwavelength information. In this work, we report on the design and experimental realization of an acoustic far-field subwavelength imaging system based on a transmitting/receiving pair for wave vector filtering and conversion. In the near-field, the transmitter is composed of a resonator array for pre-filtering the evanescent wave, and an acoustic phase grating for converting the filtered evanescent wave into propagating wave. In the far-field, a receiver that is spatially symmetrical to the transmitter is used to convert the propagating wave back to evanescent wave and perform post-filtering. By tuning the resonance frequency of the resonator array and period of the phase grating, different spatial frequency bands can be separated and projected to the far-field. Far-field imaging and edge detection of subwavelength objects are experimentally demonstrated. The proposed system brings new possibilities for far-field subwavelength wave manipulation, which can be further applied to medical imaging, nondestructive testing, and acoustic communication.The resolution of far-field acoustic imaging is limited due to the loss of the evanescent field that carries subwavelength information. In this work, we report on the design and experimental realization of an acoustic far-field subwavelength imaging system based on a transmitting/receiving pair for wave vector filtering and conversion. In the near-field, the transmitter is composed of a resonator array for pre-filtering the evanescent wave, and an acoustic phase grating for converting the filtered evanescent wave into propagating wave. In the far-field, a receiver that is spatially symmetrical to the transmitter is used to convert the propagating wave back to evanescent wave and perform post-filtering. By tuning the resonance frequency of the resonator array and period of the phase grating, different spatial frequency bands can be separated and projected to the far-field. Far-field imaging and edge detection of subwavelength objects are experimentally demonstrated. The proposed system brings new possibili...