In this article, we survey various non-contact, non-destructive testing methods by way of terahertz (THz) spectroscopy and imaging designed for use in various industrial sectors. A brief overview of the working principles of THz spectroscopy and imaging is provided, followed by a survey of selected applications from three industries-the building and construction industry, the energy and power industry, and the manufacturing industry. Material characterization, thickness measurement, and defect/corrosion assessment are demonstrated through the examples presented. The article concludes with a discussion of novel spectroscopy and imaging devices and techniques that are expected to accelerate industry adoption of THz systems.
Keywords: THz CW; THz cameras; THz pulsed imaging (TPI); THz-TDS; beam steering; building and construction; concrete; electrical cables; electronically controlled optical sampling; gas; industrial applications; manufacturing; multimode laser diodes; natural gas pipelines; non-contact; non-destructive testing (NDT); oil & polymer composites; steel fabrication; terahertz (THz); thermal barrier coatings.