Terahertz nondestructive evaluation

[8][9] The use of THz waves for non-destructive evaluation enables inspection of multi-layered structures and can identify abnormalities from foreign material inclusions, disbond and delamination, mechanical impact damage, heat damage, and water or hydraulic fluid ingression.

This non-contact, single-sided terahertz electromagnetic measurement and imaging method characterizes micro-structure and thickness variation in dielectric (insulating) materials.

The resulting THz absorption produces a unique and reproducible spectral pattern that identifies the material.

This method can be used in a fence line or aircraft mounted system that works day or night in any weather.

Evidently passive systems are inherently safe, whereas an argument can be made that any form of "irradiation" of a person is undesirable.

Because THz radiation is biologically safe (non ionisant), it can be used in high resolution imaging to detect skin cancer.

After the Shuttle Columbia accident in 2003, Columbia Accident Investigation Board recommendation R3.2.1 stated “Initiate an aggressive program to eliminate all External Tank Thermal Protection System debris-shedding at the source….” To support this recommendation, inspection methods for flaws in foam are being evaluated, developed, and refined at NASA.

The innovation described below answered the call to develop a nondestructive, totally non-contact, non-liquid-coupled method that could simultaneously and precisely characterize thickness variation (from crushed foam due to worker handling and hail damage) and density variation in foam materials.

There are millions of dollars of ultrasonic equipment in the field and on the market that are used as thickness gauges and density meters.

When terahertz nondestructive evaluation is fully commercialized into a more portable form, and becomes less expensive it will be able to replace the ultrasonic instruments for structural plastic, ceramic, and foam materials.