In the lower pictures, improved X-ray imaging technologies of KAIST researchers show substantially improved resolution of an X-ray microscope. Photo courtesy of KAIST

Researchers use unique techs called speckle-correlation imaging

A team of researchers at the Korea Advanced Institute of Science and Technology (KAIST) have found a way to substantially improve the resolution of X-ray imaging, according to the university on April 12.

The team headed by Prof. Park Yong-keun and scientist Lee Kyeo-reh used a unique technology dubbed coherent speckle-correlation imaging (CSI) to reach the breakthrough.

An X-ray microscope is designed to use electromagnetic radiation in the X-ray band to produce magnified images of any object. Since its discovery, its penetrating power has made it a versatile tool.

However, the resolution of X-ray imaging has largely been limited by the technical difficulties of X-ray lens making, the tall tasks that the KAIST team tried to tackle.

Traditionally, various lens-less imaging methods have been proposed to deal with the difficulties, but they ended up facing additional constraints on measurements or samples.

Against this backdrop, the KAIST researchers presented coherent CSI based on a designed X-ray diffuser.

CSI has no prerequisites for samples or measurements. A single-shot measurement is sufficient to retrieve the complex sample field thanks to a diffuser, they said.

They eventually achieved a special resolution of 13.9 nanometers, which is approximately one-seventh of the size of the novel coronavirus.

The exploits were published recently by the renowned peer-reviewed journal, Light: Science and Application.

“This time around, we managed to reach the resolution of around 14nm. But we will be able to reach the 1nm range using different devices of which resolution is similar to that of an electronic microscope,” said Lee Kyeo-reh, one of the corresponding co-authors of the paper.

“Unlike an electronic microscope, an X-ray-enabled microscope does not have to damage objects for observations thanks to its penetrating power. Hence, the new technology would be employed for such purposes as semiconductor investigations.”

The scientific feats were based on the KAIST team’s previous work on directly measuring the wavefront of light through a reference-free holographic image sensor based on a speckle-correlation scattering matrix approach.

The study was featured in the Nature Communications in 2016.