Since the early 1980s, the use of lasers to generate and detect ultrasonic waves in samples has generated great interest from both academia and industry. The ability to perform ultrasonic measurements on hot or moving samples without contacting the samples has been and still is, for some applications, the ideal solution. There are also a number of situations where laser ultrasound provides a unique solution, where one can benefit from the measurement system not affecting the sample being measured or the benefits of high measurement resolution that one can now obtain using laser ultrasound methods. The past decade has seen a number of interesting developments in this area, with the development of new equipment and techniques, and the commercialisation of some of the technology by groups with a strong track record in research. It seems timely that we now have a Special Issue on laser ultrasound to capture some of the latest developments and to reflect on some of the more recent scientific progress in this field.
The aim of this Special Issue was to try and take a ‘snapshot’ of the state of the art from a wide selection of some of the key researchers involved in this area. Each of these authors has an established track record in laser ultrasound and are recognised as world leaders in the field. Each contributor has been specially invited to contribute to this issue and they have also taken part in the review process, resulting in a collection of papers that have been written and reviewed by the world's leading experts in this area. Authors have also been encouraged to submit standard format research papers of previously unpublished work or papers that act as a review of the authors' own work up to the current boundaries of their research. We have tried to demonstrate the breadth of applications for which one can use laser ultrasound, together with very recent research developments, some clear demonstrations of the method at work in applications and some of the necessary background theory that underpins the basic measurement techniques.
I am sure that readers will find this a useful and informative Special Issue and also that they will find this a valuable reference resource. Finally, I would like to thank the contributors and referees for the papers in this issue, without whose support it would have been impossible to collate such a focused and valuable scientific resource.