Terahertz near-field microscopy based on an air-plasma dynamic aperture

As a novel far-infrared inspection method, the development of terahertz (THz) imaging technology has attracted considerable attention in recent years. With the unique properties of THz radiation, such as non-ionizing photon energies and broad spectral information, this imaging technique has shown powerful application potential in many fundamental research and industrial fields. However, the resolution of THz imaging is always limited due to its long wavelength. The introduction of optical near-field techniques can greatly enhance the resolution, but it is always essential to require that a THz source or detector approach the sample from as far as possible. For soft or liquid materials in biomedical sensing and chemical inspection, these samples may be easily damaged and the THz source or detector may be contaminated in traditional THz near-field techniques. Hence, it still remains a challenge to achieve THz near-field microscopy in wider application fields.