TWI has been developing laser-ultrasonic testing techniques for many years and is now able to provide services harnessing this relatively nascent technology to members.
Laser ultrasonics is a cutting edge non-destructive testing (NDT) method in which lasers are used to generate, and then measure, ultrasonic waves in a material.
Laser-ultrasonic testing is able to remotely generate ultrasound in materials without contact, leaves a very small footprint so that it can be applied to irregular geometries, and allows access to restricted areas via fibre optics.
Our resources
- IOS research kit including laser generator, laser receiver, ADC card, scanner and software
- Generation laser with 9ns pulse duration
- Generation laser with 5-6ns pulse duration
The benefits of laser-ultrasonic testing
- Non-contact and remote, allowing inspection of samples at high temperature, e.g. during welding with restricted access
- Small and adjustable footprint
- Enables inspection of small and complex geometries
- High frequency capable of detecting very small flaws
- Laser beam scanning method for full coverage of inspection samples
Applications for laser-ultrasonic testing
- Industrial in-process measurements on hot, hazardous, remote samples which may be moving at high speeds
- High-resolution measurement of small parts
- Inspection of complex structures
- TWI is pursuing various laser-ultrasonics projects involving the inspection of friction stir welds, laser material depositing and composite materials
Our work with the technology
Intensive research on the mechanisms of generation and properties of the ultrasound produced has been carried out since the 1980s. A technology readiness level of between six and eight has been reached by certain laser-ultrasonic applications, such as thickness measurement for steel tubes coming out from the mill and damage detection of composite aircraft components.
TWI has carried out a number of research projects in developing laser-ultrasonic testing as an online inspection tool for different welding processes and continues to investigate the technology’s potential.
Broadly speaking, the mechanisms of generating ultrasound using this method are laser thermal shock and laser ablation. They both deposit a rapid laser pulse on the material surface, inducing a sudden stress in the sample. The stress then propagates in the material as ultrasound. Broadband, multi-mode waves are generated simultaneously.
For more information about laser-ultrasonic testing and TWI's other NDT services, please email contactus@twi.co.uk.