The time-resolved nonlinear ghost imaging camera uses a nonlinear crystal to convert standard laser light to terahertz patterns, allowing the reconstruction of complex samples using a single terahertz pixel. Image Credit: University of Sussex
This year, a team of physicists based at the University of Sussex, in the UK, published a paper in the journal Optica in which they describe the groundbreaking technology they established which sees terahertz (THz) radiation being utilized to create the world’s first nonlinear camera.
The technology created by the team allows for the production of high-resolution images of the molecular structure of solid objects without harming the sample. Researchers believe that the innovation will be highly influential in future developments in airport security protocols, intelligent car sensors, quality control in manufacturing, and the establishment of sensors that can detect disease, such as scanners for the detection of skin cancer.
Ground-Breaking Technology That Can Detect Molecular Structures
Like x-ray waves terahertz (THz) waves easily penetrate solid substances. Unlike x-rays though, THz is not harmful and is safe for use even on the most delicate biological samples. This means that imaging based on THz waves can produce images of the molecular composition of a wide range of samples, without destroying or causing harm. It can be used to determine the composition of the sample, providing an identification of the substance.
At the University of Sussex, a team led by Professor Marco Peccianti, Luana Olivieri, and Dr. Juan S. Totero Gongora aimed to develop a new breed of THz camera, able to detect THz waves with levels of accuracy that had not yet been accomplished by previous devices.
The establishment of a device capable of producing images using THz radiation, known as ‘hyperspectral' images due to the generation of each pixel from the electromagnetic signal produced by that specific point of the object, had been considered outside of the realms of possibility.
However, the team was able to do what was considered impossible. Using a single-pixel camera to gather data on patterns of THz light produced from sample objects the team was able to construct a prototype capable of detecting how THz light is altered by objects. The team combined this information with the data collected on the original pattern, allowing the camera to produce an image of the object along with its chemical composition.
As sources of THz radiation are generally quite faint, making them difficult to detect, the team incorporated the use of a standard laser which was shone onto a non-linear material that could convert visible light into THz. The camera they created generates THz electromagnetic waves in close proximity to the sample being tested, allowing the THz waves to pass directly through the object and produce an image of its shape and chemical composition.
Scanners to detect disease?
The work of the British team is significant because it addresses the major problem of using THz cameras to produce images. The chemical compositions of the objects visualized with this technique can be easily corrupted, however, the current prototype overcomes this challenge as it retains the chemical fingerprint of the object so that it can be thoroughly investigated in unprecedented detail.
Previously, the work around this technology has been purely theoretical, therefore, what has been achieved here represents a major step toward realizing the full potential of THz cameras. Next, researchers will focus on advancing the technology so that the imaging reconstruction process can be sped up, which will hopefully lead to the use of these cameras in numerous applications, such as in airport security, next-generation sensors, and even in medical scanners that may be developed to detect the presence of disease.
One application that is of particular interest it the development of a scanner to diagnose skin cancer, which will help with early diagnosis and therefore treatment outcomes.
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