Micro-resolution ultrasonic testing system for aerospace composite materials using HeNe and IR lasers

Micro-resolution ultrasound is a process that can characterize materials using a focused beam immersion ultrasonic probe, an infrared (IR) laser vibrometer, an immersion tank, and a sample holder. The focused beam immersion ultrasonic probe has a spot size of 0.3mm with 20MHz at a focal point of 28mm. The focal diameter of the IR laser can be as small as 10micrometers, allowing for a higher probability-of-detection (POD) for defects in materials. A sample of 2024 grade aluminum, similar to what is used in commercial and civil aviation aircraft was examined. A system interface using MATLAB was used to automate a nondestructive evaluation process that produced microscopic resolution of the control sample and the defective sample. In conclusion, this study showed that microscopic resolution can be achieved with less sample preparation using an IR laser, in place of a HeNe laser that is traditionally used.