Abstract

Computed tomography (CT) has been used for decades in industrial nondestructive evaluation (NDE) fields as well as medical applications. Its characteristics of high resolution and accuracy in image reconstructions have made CT the first choice in medical imaging applications. Although Gamma Ray CT has strong penetration ability and can be used in relatively large-scale NDE applications, most CT methods can only be used in small-scale applications. Traditional CT methods employ open beams, and this makes CT incapable of plane or curvy interface discontinuity detection.

Time Domain Reflectometry (TDR) is another NDE method in field applications. TDR is widely used in the cable testing industry and some other fields where its simplicity and intuitiveness attract field application engineers. When it is applied in high-resolution applications such as corrosion detection and void detection in civil engineering, the attenuation of reflected signal bumps confines TDR to small-scale applications.

Time Domain Reflectometry/Time Domain Transmission Computed Tomography (TDR/TDT CT) is a novel technology that combines CT with TDR/TDT. It uses tail movement in TDR data curves as the indication of time integral, a variation of line integral in CT technology. It employs man-made material guiding paths as the simulation of radiation rays in CT applications. TDR/TDT CT is the first type of CT application that uses guiding paths to guide EM waves through the media. This feature has a number of benefits such as capability of detection on plane and curvy interface, and in three-dimensional applications. TDR/TDT CT uses tail movement rather than reflected signal bump, as in TDR applications, and this change basically eliminates the attenuation of the reflected signals and makes TDR/TDT CT suitable for large scale application while keeping the inherent high resolution features inherited from CT algorithms.

This dissertation presents the theoretic basis of TDR/TDT CT and suggests many field application methods and procedures. It also introduces the experiment used to prove the concept of TDR/TDT CT, and presents the results. Finally it introduces conclusions and future work.