Airy-Based High-Frequency Acoustic Lens for Underwater High-Resolution Ultrasonic Imaging

• Published in: IEEE transactions on instrumentation and measurement Vol. 74; pp. 1 - 8
• Main Authors: He, Jingrong, Li, Zhaoxi, Wei, Xiongwei, Zhang, Juan, Li, Yi, Wang, Yecheng, Yang, Yiheng, Zhao, Jianxin, Hou, Chenxue, Fei, Chunlong, Yang, Yintang
• Format: Journal Article
• Language: English
• Published: New York IEEE 2025; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic focusing; Acoustics; Airy-based (AB) lens; Bandwidth; Depth of field; Design; Design parameters; Fabrication; Focusing; Fresnel lenses; high frequency; High resolution; Image resolution; Imaging; Ion beams; Lens design; Lenses; Metamaterials; Piezoelectric ceramics; Signal resolution; Simulation; Transducers; Ultrasonic imaging; ultrasonic transducer; ultrasound imaging; Underwater
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2025.3542108

Flat acoustic lenses, such as Fresnel lenses and metamaterial lenses, have attracted much attention in ultrasound focusing due to their compact structure and high efficiency. However, the development of flat acoustic lenses is currently limited by low frequency, thin bandwidth (BW), complex fabrication, and serrated edges during production. This article proposes an ultrasound transducer (UT) fabricated using PZT-4 piezoelectric ceramic, incorporating two flat lenses: an Airy-based (AB) lens and an AB hole (ABH) lens. Both lenses are designed based on the binary Airy distribution with a phase difference of <inline-formula> <tex-math notation="LaTeX">\pi </tex-math></inline-formula>. First, the generation of 5-MHz Airy-focused beams is simulated, and the ABH lens was designed with the aperture radius of the hole (<inline-formula> <tex-math notation="LaTeX">r_{h} =5 </tex-math></inline-formula> mm) to improve the imaging lateral resolution. The simulation shows that the focal length of the AB lens is 12.14 mm, with a depth of field of 1.43 mm. The focal length of the ABH lens is 12.22 mm, with a depth of field of 1.73 mm, <inline-formula> <tex-math notation="LaTeX">f_{\text {number}} =0.48 </tex-math></inline-formula>. In the experiments, it was observed that the ABH lens demonstrated a 7.4% improvement in lateral resolution and a 26.9% enhancement in BW compared to the AB lens. The imaging resolution achieved with the ABH lens reached the high resolution of <inline-formula> <tex-math notation="LaTeX">0.45\lambda </tex-math></inline-formula>. This work enhances the design of lenses by enabling the generation of focused acoustic beams through the adjustment of the lens design parameters, offering promising potential for underwater imaging applications.