Seeing Clearly With THz Imaging
Terahertz radiation lies between the microwave and the infrared regions of the electromagnetic spectrum. Its frequency typically ranges from 0.1 THz to 10 THz, which corresponds to wavelengths from 3 mm to 0.03 mm. Falling within the gap between photonic and electronic devices, historically THz radiation is relatively under-developed and efficient sources and detectors are lacking. However, THz radiation has many interesting characteristics for potential applications:
- With higher frequencies, THz radiation can carry more information than microwaves, making it appealing for future wireless communication.
- The longer wavelength of THz radiation makes scattering by dust, fog, and smoke significantly less than infrared light.
- Fabric, paper, cardboard, plastic, leather, timber, and ceramic are transparent to THz radiation, which means it can penetrate through these opaque materials.
- Metals are perfect reflectors for THz radiation.
- Many molecules have their vibrational resonances in the THz range, allowing identification with their spectral signatures.
- Unlike x-ray radiation, THz radiation is non-ionizing, thus is harmless to living beings and delicate electronic components.
Low impact, extremely high value
We use a technique called terahertz time-domain spectroscopy (THz-TDS) combined with fast raster scanning to image samples of interest. It is a non-invasive (non-contact) and non-destructive (non-ionizing) imaging technology. In THz-TDS, ultrafast THz pulses emitted from a transmitter interact with the sample under test and create reflections that are then collected by a receiver. These reflected THz pulses are analyzed in both the time and frequency domains to create THz images of the scanned area. After signal processing, the whole 3D image of the sample can be reconstructed.
Riding the continuous wave
In addition to THz-TDS, we are also invested in continuous-wave (CW) THz imaging technology. We design and develop real-time THz CW cameras that are compact and lightweight, ultimately leading to portable THz systems that can be easily deployed in the field for rapid THz imaging.