An autofocus algorithm for flexible ultrasonic arrays based on maximisation of image contrast

Alan J. Hunter; Bruce W. Drinkwater; Paul D. Wilcox

doi:10.1117/12.776241

10 April 2008 An autofocus algorithm for flexible ultrasonic arrays based on maximisation of image contrast

Alan J. Hunter, Bruce W. Drinkwater, Paul D. Wilcox

Proceedings Volume 6935, Health Monitoring of Structural and Biological Systems 2008; 69350Z (2008) https://doi.org/10.1117/12.776241
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2008, San Diego, California, United States

Abstract

This paper presents an algorithm for autofocusing imagery obtained from a flexible ultrasonic array with unknown geometry. The relative positions of the array elements are parameterised using a polynomial function. The polynomial coefficients are estimated by iterative maximisation of the SAFT image contrast via simulated annealing. The estimate can be refined in the final stages of iteration using the full 3-D matrix of echo data via the total focusing method. The resultant polynomial gives an estimate of the array geometry and the profile of the surface that it has conformed to, providing a well-focused, high quality image. The algorithm is demonstrated on experimental data obtained using a flexible array prototype.

Citation Download Citation

Alan J. Hunter, Bruce W. Drinkwater, and Paul D. Wilcox "An autofocus algorithm for flexible ultrasonic arrays based on maximisation of image contrast", Proc. SPIE 6935, Health Monitoring of Structural and Biological Systems 2008, 69350Z (10 April 2008); https://doi.org/10.1117/12.776241

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