ULTRASONIC IMAGING USING A FLEXIBLE ARRAY: IMPROVEMENTS TO THE MAXIMUM CONTRAST AUTOFOCUS ALGORITHM
- Department of Mechanical Engineering, University of Bristol (United Kingdom)
In previous work, we have presented the maximum contrast autofocus algorithm for estimating unknown imaging parameters, e.g., for imaging through complicated surfaces using a flexible ultrasonic array. This paper details recent improvements to the algorithm. The algorithm operates by maximizing the image contrast metric with respect to the imaging parameters. For a flexible array, the relative positions of the array elements are parameterized using a cubic spline function and the spline control points are estimated by iterative maximisation of the image contrast via simulated annealing. The resultant spline gives an estimate of the array geometry and the profile of the surface that it has conformed to, allowing the generation of a well-focused image. A pre-processing step is introduced to obtain an initial estimate of the array geometry, reducing the time taken for the algorithm to convergence. Experimental results are demonstrated using a flexible array prototype.
- OSTI ID:
- 21260294
- Journal Information:
- AIP Conference Proceedings, Vol. 1096, Issue 1; Conference: 35. annual review of progress in quantitative nondestructive evaluation, Chicago, IL (United States), 20-25 Jul 2008; Other Information: DOI: 10.1063/1.3114338; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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