- Water provides a strong contrast in terahertz imaging
- Terahertz measurements can help to optimize irrigation strategies
- Cw-Terahertz systems permit a flexible choice of the operating frequency
- Recommended systems: TeraFlash pro, Imaging Extension, TeraFlash smart, TeraSpeed
Terahertz radiation for measurements of water content
Water strongly attenuates terahertz radiation, with liquid having an even greater effect than water vapor. Water-contrast terahertz imaging thus enables humidity measurements in industrial quality control, or the analysis of water absorption and distribution mechanisms. Of particular interest are in-situ measurements of the water content of plant leaves. This helps to avoid drought stress and to optimize irrigation strategies, a topic of relevance for agricultural crops grown in arid regions, where both desertification and water shortages present serious threats. Terahertz imaging visualizes not only the leaf veins, but can identify regions of insufficient water content as well. Studies of water transport mechanisms in plants, or “plant physiology” in general, could thus be prospective applications for terahertz-based imaging and monitoring systems.
Terahertz wave systems - compact and inexpensive
Whilst both frequency-domain and time-domain systems have proven suitable for terahertz imaging, continuous-wave systems in particular have become intriguingly compact and inexpensive. In addition, they enable users to choose the operating frequency in dependence of the required spatial resolution, and the transmission properties of the sample under scrutiny.
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- Related Literature
- Review paper: Naftaly, M., et al., Industrial applications of terahertz sensing: State of play, Sensors (2019)
- Publication: M. Yahyapour et al., Fastest thickness measurements with a terahertz time-domain system based on electronically controlled optical sampling; Appl. Sciences (2019)
- Conference Abstract: M. Yahyapour et al., Non-Contact Thickness Measurements with Terahertz Pulses, WCNDT 2016
- Publication: F. Rettich et al., Field intensity detection of individual terahertz pulses at 80 MHz repetition rate; J Infrared Milli. Terahz. Waves 36:7 (2015)
- Publication: N. Vieweg et al., Terahertz-time domain spectrometer with 90 dB peak dynamic range; J Infrared Milli. Terahz. Waves 35:10 (2014)
- Related Applications