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Spinning ‘metasurfaces’ provide compact thermal imaging for navigation and medical imaging

The system uses a stack of spinning metasurfaces to break down thermal light into its spectral and polarimetric components (Credit: Xueji Wang, Purdue University)
The system uses a stack of spinning metasurfaces to break down thermal light into its spectral and polarimetric components (Credit: Xueji Wang, Purdue University)

Spinning ‘metasurfaces’ – ultra-thin structures that manipulate light in complex ways – have enabled a compact new approach to thermal imaging.

With potential applications in autonomous navigation, security and medical imaging, the technology was developed by researchers at Purdue University in Indiana.

“Our method overcomes the challenges of traditional spectral thermal imagers, which are often bulky and delicate due to their reliance on large filter wheels or interferometers,” said research leader Zubin Jacob. “We combined meta-optical devices and cutting-edge computational imaging algorithms to create a system that is both compact and robust while also having a large field of view.”

The system uses a stack of spinning metasurfaces to break down thermal light into its spectral (wavelength) and polarimetric components. This allows the imaging system to capture the spectral and polarisation details of thermal radiation, as well as the intensity information that is acquired with conventional thermal imaging.

The researchers showed that the new system can be used with a commercial thermal camera to successfully classify various materials, a task that is typically challenging for conventional thermal cameras. They said that the method’s ability to distinguish temperature variations and identify materials based on spectro-polarimetric signatures could help boost safety and efficiency for a variety of applications, including autonomous navigation.

“Traditional autonomous navigation approaches rely heavily on RGB cameras, which struggle in challenging conditions like low light or bad weather,” said Xueji Wang, first author of a paper on the work.

“When integrated with heat-assisted detection and ranging technology, our spectro-polarimetric thermal camera can provide vital information in these difficult scenarios, offering clearer images than RGB or conventional thermal cameras. Once we achieve real-time video capture, the technology could significantly enhance scene perception and overall safety.”

The new method could be especially useful for applications that require detailed thermal imaging, the team said. “In security, for example, it could revolutionise airport systems by detecting concealed items or substances on people,” said Wang. “Its compact and robust design enhances its suitability for diverse environmental conditions, making it particularly beneficial for applications such as autonomous navigation.”

The team aims to extend the method to room temperature imaging, as the use of metasurface stacks has so far restricted the method to high-temperature objects. They plan to do this using improved materials, metasurface designs, and techniques like anti-reflection coatings.

The work was published in Optica.


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