Panel Step/Gap Mismatch Measurement

We propose to demonstrate the feasibility of a fiber optic coupled time-domain terahertz (TD-THz) instrument to measure the substrate step/gap mismatch dimensions of aircraft panel and doors after exterior coatings have been applied. Our concept instrument will be a hand-held, panel step/gap measurement sensor, to be developed in this project, which is coupled through a light weight umbilical to our commercial off-the shelf Picometrix TD-THz instrumentation control unit. The proposed instrument will be able to measure substrate step/gap dimensions through a variety of coating and paints. The TD-THz measurement process is suitable for both composite (conductive and non-conductive) and metallic substrates. The TD-THz instrumentation system can acquire measurements at up to 100 Hz, which allow the operator to rapidly scan panels and doors. TD-THz reflection non destructive evaluation imaging is like an electromagnetic analog to a laminographic ultrasound B-scan, but with several advantages: The TD-THz measurement is non-contact, requires no special preparation of the surface, can be used to determine the dimensions of small structures, and has micron (sub mil) resolution or better.