Journal of Pure and Applied Ultrasonics

Kiran Kumar Amireddy ¹, Prabhu Rajagopal ², Krishnan Balasubramaniam ²

Affiliations
1 Chaitanya Bharathi Institute of Technology, Hyderabad-500 075, Telangana, India., IN
2 Centre for Non-destructive Evaluation and Department of Mechanical Engineering, Indian Institute of Technology- Madras, Chennai-600 036, Tamil Nadu, India., IN

Abstract

Phononic crystals, which are structures with periodicities on the scale of the incident sonic wavelength, are of much interest due to the potential for new properties, such as band gaps and high-efficiency transmission. The phononic properties of holey structures have been particularly studied because of their ease of fabrication and scalability. Recently our group has demonstrated super resolution imaging using structured holey lenses. However, the resolution capacity of phonic crystals having a periodic arrangement of regular holes is limited by the Wood anomaly, at which some of the wave field components vanish from the transmission spectrum. This paper discusses an alternative approach to overcome the Wood anomaly, using aperiodic lenses. We show deep subwavelength imaging (λ/32) of a surface notch in a mild steel sample using the proposed unstructured phononic holey lens.

Keywords

Periodicity, Phononic Crystal, Super Resolution, Unstructured Phononic Lens, Wood Anomaly.

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