Ultrasonic TOF-CT system for wooden pillars

We propose an ultrasonic time-of-flight (TOF) computed-tomography (CT) system for visualizing the internal structure of historic relics such as the wooden pillars of shrines. Using ultrasonic, we realized a safe and portable measuring system. However, there occur some problems in the application of ultrasonic to CT. The ultrasonic wavelength is considerably longer than X-ray wavelength, and, the propagation speed varies over a wide range. Hence, the ultrasonic wave properties significantly affect the CT images. In this paper we present an ultrasonic TOF CT system developed by us, and, the ultrasonic wave properties on CT is evaluated