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High-speed THz system for industrial quality control

17 March 2020 | Product
by Ian Michael

Measurement speed becomes particularly relevant if the task involves rapidly moving samples, e.g. thickness gauging in extrusion lines or items on fast conveyor belts that may need to be screened with single-millimeter resolution. In contrast to conventional terahertz time-domain spectrometers, the TeraFlash smart does not use any mechanical delay unit, but includes two synchronised femtosecond lasers with an electronic delay (“electrically controlled optical sampling”, ECOPS). This concept results in very high measurement speeds: the TeraFlash smart acquires 1600 complete terahertz waveforms per second.

Within a measurement time of only 625 µs, the TeraFlash smart achieves a spectral bandwidth of 3 THz. The dynamic range of the pulse trace is greater than 50 dB. Within one second of averaging, this value increases to >80 dB and the bandwidth exceeds 4 THz. Users can flexibly adjust the terahertz path length from 10 cm to 180 cm. The fibre-coupled transmitter and receiver antennas can be flexibly positioned and enable measurements in transmission or reflection.

Reflection measurements are particularly suitable to determine layer thicknesses, for example to investigate the wall thickness of plastic pipes or the structure of polymer coatings or single- and multi-layered paint. The 10 m long fibre cables allow a spatial separation of the control unit from the measurement head, which can even be mounted on a robot arm.