Rapid control of machined glass fiber reinforced plastics by single shot terahertz time domain spectroscopy

We apply single shot THz Time Domain Spectroscopy to control glass fiber reinforced plastics that were machined during their production. The THz imaging reveals that the mechanical processing as hole punching introduced significant modifications to the composite structures, also beyond the directly impacted region. These changes can be precisely localized and further characterized in order to classify the types of defect. The results show that the time of flight information is particularly sensitive to changes in the complex fiber and polymer matrix network. They can be visualized and quantified with B- and C-scans. Thanks to the ultrashort duration and high repetition rate of acquisition, the single shot technology is suited for the control of composites within cycle time of industrial production.