High-throughput terahertz imaging: progress and challenges

Abstract

Many exciting terahertz imaging applications, such as non-destructive evaluation, biomedical diagnosis, and security screening, have been historically limited in practical usage due to the raster-scanning requirement of imaging systems, which impose very low imaging speeds. However, recent advancements in terahertz imaging systems have greatly increased the imaging throughput and brought the promising potential of terahertz radiation from research laboratories closer to real-world applications. Here, we review the development of terahertz imaging technologies from both hardware and computational imaging perspectives. We introduce and compare different types of hardware enabling frequency-domain and time-domain imaging using various thermal, photon, and field image sensor arrays. We discuss how different imaging hardware and computational imaging algorithms provide opportunities for capturing time-of-flight, spectroscopic, phase, and intensity image data at high throughputs. Furthermore, the new prospects and challenges for the development of future high-throughput terahertz imaging systems are briefly introduced.

Unveiling terahertz wave stress effects and mechanisms in Pinellia ternata: Challenges, insights, and future directions

“…Compared to other electromagnetic waves, terahertz waves are noted for their unique penetrating and non‐thermal effects and have become an emerging source of stress, especially in the field of plant physiological regulation. The special effect of terahertz waves stems from their frequency range, which allows them to penetrate many common substances, including biological tissues (Li et al, 2023). At the same time, the non‐thermal effect of terahertz waves allows them to affect living organisms without causing significant temperature increases.…”

Terahertz Detection by Asymmetric Dual Grating Gate Bilayer Graphene FETs with Integrated Bowtie Antenna

“…Terahertz sensing can be applied in many different fields: astronomy [ 3 ], spectroscopy (the maxima of the spectral response of many molecules and solids lies in the THz range; as the THz response of many substances has been found to be stronger and more distinctive than the one found in the microwave, IR and visible spectral ranges, THz spectroscopy can be advantageously used to define fingerprints of these substances) [ 4 ], communications (that can benefit of a bandwidth considerably higher than the current communication systems based on microwaves) [ 5 , 6 , 7 , 8 ], security (both spectroscopy and imaging to detect concealed objects can be used) [ 9 , 10 , 11 ], metrology [ 12 ], etc. The resolution of THz radiation is limited by light diffraction and its value is similar to the one of the human eye; therefore, THz rays (T-rays) can be used to generate precise images that, additionally, benefit from the unique properties of THz radiation: materials commonly used in packaging for shipping (plastics, cardboard, …) are transparent to T-rays, while opaque in the visible spectrum, allowing the inspection of concealed objects [ 13 ]. Additionally, as T-rays can penetrate few millimeters deep the human skin, they can be used to examine subcutaneous tissue for in vivo diagnosis of skin cancer [ 14 ].…”

A Low-Loss Hollow-Core Waveguide Bundle for Terahertz Imaging under a Cryogenic Environment

“…Terahertz (THz) waves (0.1–10 THz) have stronger penetration compared to visible and infrared radiation, which have attracted widespread attention in various imaging applications ranging from industrial inspections to medical diagnosis. − According to the operating mode of the THz source, THz imaging can be divided into continuous-wave imaging and pulsed imaging. The THz pulsed imaging (TPI) system is able to distinguish normal and diseased tissues, as well as the content and state of tissue water by analyzing the difference of absorption spectra and specific principal component information on frequency-domain signals .…”