Abstract
Our previous study showed that images of adhesive regions between auto body steel sheets can be obtained using air-coupled ultrasonic sensors in oblique beam setting. This study introduced focus type sensors to improve spatial resolution and to reduce spaces required sensor arrangement. First, flat type and focus type sensors were compared in through transmission tests. Secondly, in the imaging tests of square holes with various sizes, it was confirmed that spatial resolution was improved using focus type sensors. Then, images of adhesive regions were obtained with high resolution by scanning the focus type sensors.
