SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Picometrix, LLC
2925 Boardwalk Drive
Ann Arbor, MI 48104 - 6765
(734) 864-5600

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Shirley Evans
evanss@lunainc.com
2925 Boardwalk Drive
Ann Arbor, MI 48104 - 6765
(540) 961-6724

CORPORATE/BUSINESS OFFICIAL (Name, E-mail, Mail Address, City/State/Zip, Phone)
Shirley Evans
evanss@lunainc.com
2925 Boardwalk Drive
Ann Arbor, MI 48104 - 6765
(540) 961-6724

Estimated Technology Readiness Level (TRL) at beginning and end of contract:
Begin: 3
End: 4

Technology Available (TAV) Subtopics
NDE Sensors is a Technology Available (TAV) subtopic that includes NASA Intellectual Property (IP). Do you plan to use the NASA IP under the award?
No

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
In Phase II, Picometrix proposes to design, construct, test, characterize, and deliver a prototype differential time domain terahertz shearographic imaging system. The differential imaging methods developed in Phase I will be improved and the methods implemented in turn-key software and hardware. In Phase I the feasibility of using differential time domain THz imaging methods to enhance the contrast and detectability of features such as disbonds was demonstrated. Kissing disbonds and cracks may only weakly reflect the THz pulses in conventional THz imaging. The Phase I project developed the methods of shearographic loading of the samples, and used penetrating THz pulses to detect the subsurface deformation of the defects with better contrast than traditional THz imaging. In a disbond there is a region where the two sides of the material are not adhered, and the space between the two sides are essentially so close that THz interface reflection pulses from the non-adhered region may be partially cancelled out.. The defect signature may be only weakly detectable compared to when the spacing is greater than the minimum THz wavelength. The differential images null background clutter and highlight the subsurface distortion of the defects under loading.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
THz reflection imaging is a proven NDE technology for imaging sub-surface features, flaws, and defects within space flight structures such as thermal protection systems (ablative resin honeycomb, TUFI, SOFI), inflatable space habitats, composite overwrap pressure vessels, and radomes. THz NDE can detect voids, disbonds, and damage such as tearing and micro-meteorite impact. Material include Kevlar, Zylon, and other non-conductive composites. Differential THz imaging should improve the detectability of defects in each of these applications.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
THz gages are used in industry to measure the thickness of multi-layer sheet materials: plastic film, insulation, foam sheets, roofing, paper, and other products that are extruded in presses. THz gauges are used to measure the thickness of aerospace coatings. The differential imaging method will improve the detectability of interfaces and delaminations in the manufacturing of these materials.