Practically applied techniques for ultrasonic biomedical imaging employ delay-and-sum (DAS) beamforming which can resolve two objects down to 2.1λ within the acoustic Fresnel zone. Here, we demonstrate a phononic metamaterial lens (ML) for detection of laterally subwavelength object features in tissue-like phantoms beyond the phononic crystal evanescent zone and Fresnel zone of the emitter. The ML produces metamaterial collimation that spreads 8x less than the emitting transducer. Utilizing collimation, 3.6x greater lateral resolution beyond the Fresnel zone limit was achieved. Both hard objects and tissue approximating masses were examined in gelatin tissue phantoms near the Fresnel zone limit. Lateral dimensions and separation were resolved down to 0.50λ for hard objects, with tissue approximating masses slightly higher at 0.73λ. The work represents the application of a metamaterial for spatial characterization, and subwavelength resolution in a biosystem beyond the Fresnel zone limit.

超声生物医学成像的实际应用技术采用了“延迟和”（DAS）波束成形技术，该技术可以分辨两个菲涅耳声区内的2.1λ以下的物体。在这里，我们演示了一种声子超材料透镜（ML），用于检测发射体的声子晶体消失区和菲涅耳区以外的组织状体模中的横向亚波长物体特征。ML产生超材料准直，其散布比发射换能器小8倍。利用准直仪，横向分辨率比菲涅耳区极限高3.6倍。在菲涅耳区极限附近的明胶组织模型中检查了硬物和组织近似质量。横向尺寸和分离得以解决下降到0.50 λ对于坚硬的物体，组织的近似质量略高，为0.73λ。这项工作代表了超材料在空间特征和亚波长分辨率在菲涅耳区范围以外的生物系统中的应用。