Pulsed Terahertz Imaging for Nondestructive Evaluation

Pulsed terahertz imaging, or time-domain terahertz (TD-THz) has been used for Nondestructive Evaluation (NDE) of the sprayed on foam insulation of the space shuttle external fuel tank. TD-THz is a non-contact method to produce images of internal structure without ionizing radiation. Wider acceptance of TD-THz in NDE applications has been slowed by the size and cost of the systems, and the fragile coupling of the laser source to the sensor heads. Recent advances has allowed these systems to be reduced in size and weight by close to a factor of 20 while increasing performance and reducing cost. using optical fiber allows remote inspection and robust alignment. Combine those advances is Picometrix' patented fiber-coupled sensors and robust field-deployable TD-THz systems are now possible. This talk will present the wide range of NDE applications that are currently being conducted using these systems. TD-THz has been used to: detect corrosion under insulation on pipes; detect delaminations and water intrusion in radomes; identify voids and disbonds in fiber reinforced resin pipeline repairs; produce cross sectional images of objects using CT-like reconstruction; conduct non-contact thickness measurement of paint layers; and more.