(Nanowerk News) Loughborough University scientists were the first to show that terahertz wave cameras can capture 3D images of microscopic objects hidden inside small objects.
Lead researcher Dr Luana Olivieri said although the research is still in its early stages, the team’s latest study – primarily funded by the ERC Horizon 2020 Research and Innovation program – could have “huge implications for a wide range of relevant areas of cancer screening, safety and ingredients research”.
The research, in collaboration with Professor Marco Peccianti, Dr Luke Peters, Dr Juan S. Totero and a team of experts from the Emergent Photonics Research Center (EPicX), shows that terahertz waves can be used to find and recognize embedded objects and features, such as cracks and bubbles, in microscopic three-dimensional space.
The study has been published in ACS Photonics (“Terahertz Nonlinear Ghost Imaging via Plane Decomposition: Towards Close-range Micro-Volumetry”).
Terahertz waves are an unexplored part of the electromagnetic spectrum with a frequency range between microwaves and infrared light. They have several properties that make them very useful, such as their ability to penetrate opaque objects without causing damage.
However, one of the main problems in the field of terahertz imaging is the limited ability to see microscopic objects.
Dr Olivieri and the EPicX team have overcome these limitations by developing a unique approach known as ‘time-resolved nonlinear phantom imaging’, which incorporates a variety of advanced detection methods and involves manipulating light and measuring how light travels through objects over time.
Their method allows smaller objects to be seen more clearly, though until now, it had only been shown to work on 2D objects.
In their latest study, the researchers proved that this technique can capture 3D images of microscopic objects by probing a 4mm by 4mm by 600μm (micron) cube with terahertz radiation.
The researchers’ imaging techniques allowed them to separate and distinguish information from different depths and create detailed 3D images of the cube with extremely high accuracy – allowing them to observe the chemical and physical properties of the objects inside in ways that were not possible before. .
Dr Olivieri and team were able to see features hidden in cubes as small as 60 microns, roughly the width of a human hair.
While it may not seem that small, terahertz waves can usually only identify objects about 300 microns or larger, which is why terahertz was previously excluded from microscopes.
“This new approach is possible because it allows us to see things that are too small or too obscure to reach with traditional methods”, Dr Olivieri said of the importance of the study.
“Reading the story of how light travels through an object is often a complex task, but with this process, we can retrieve encrypted information, uncover multidimensional data to reveal hidden and ‘invisible’ objects at the micro scale.
“Most importantly, terahertz allows us to see through objects that are not transparent with visible light and produce 3D images.”
Dr Peters added: “In medicine, terahertz imaging can be used to detect and diagnose skin cancers that are invisible to the naked eye.
“In security, it can be used to increase the resolution of scanners used to search for weapons or explosives that people are hiding, without the need for physical inspection or intrusive searches.
“And in materials science, terahertz imaging can be used to study the properties of new materials and identify defects or impurities that can affect their performance.
“Our work allows us to extend this capability into the microscopic domain. I am enthusiastic about the potential benefits to society.”
Professor Peccianti – director of EPicX – commented: “This work was developed as part of the Center for Emerging Photonics Research at Loughborough University, whose scope is to gather a critical core of scientists around key technological-economic and social challenges and approach them through photonics and terahertz technologies.”