Very high speed THz imaging of foam density and other defects

• Published in: 2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz) pp. 1 - 2
• Main Authors: White, Jeffrey S., Zimdars, David, Duling, Irl
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.09.2016
• Subjects: Density measurement; Image resolution; Imaging; Reflection; Substrates; Thickness measurement; Weight measurement
• ISSN: 2162-2035
• DOI: 10.1109/IRMMW-THz.2016.7758567

Very high speed TD-THz imaging (37 seconds per square foot) and measurement of a wide range of materials are presented and discussed. There are numerous applications requiring the ability to quickly image very large areas with mm resolution (e.g., heat shield on Orion spacecraft). At scan rates of 1 square foot in 37 seconds, a square meter with 2.5 mm resolution can be scanned in approximately 6.5 minutes, 0.5 mm resolution in 10 minutes. Single THz waveform dynamic range values over 55dB are maintained. A particularly interesting set of manufactured materials are high performance foams, which require very precise measurement of sheet thickness and basis weight. That is, a very high speed measurement of density is required. THz can easily make such measurements. Of further interest to the manufacturers is to not only measure overall sheet density but simultaneously measure also quickly probe (i.e., imaging) small defects within the sheet. This results reported will concentrate on the overall and small defect measurements thickness, basis weight and therefore density of foam materials and the detection of small density defects in the sheet are presented.