Menlo’s customers have successfully implemented THz-TDS spectrometers for non-destructive testing of a variety of materials. According to Krok, one of the most in-demand applications is the measurement of layer thickness. She says that terahertz spectroscopy can determine this with the micron-level accuracy, in multi-layered systems and with either very thick or very thin layers.
Also in Germany, a Fraunhofer HHI research group is currently working on several industry-relevant themes, recently demonstrating what it describes as 'attractive applications' in fields from security and medicine to biology and non-destructive materials testing. Elsewhere, San Jose outfit TeraSense has developed terahertz technology for the automotive, ceramic and security industries - amongst others.
As Taday explains, the instrument can also be used to image seed kernels, semiconductors, composites, plastics, paints, skin and even tooth enamel. Terahertz light is generated by firing ultrashort pulses of laser light at a photoconductive antenna, generating electron-hole pairs in the GaAs substrate.
Elsewhere in Germany, BATOP Optoelectronics is also using PCAs as terahertz transmitters and receivers to build its time-domain terahertz spectrometers. Its PCA consists of a thin-film metal structure acting as a dipole antenna on an GaAs or indium gallium arsenide (InGaAs) semiconductor wafer that absorbs femtosecond laser pulses.