Aston University improves views through scattering tissues

29 Oct 2024

Approach based on orbital angular momentum could assist surgeries and biopsies.

A project at Aston University has developed a technique for improving light's propagation through scattering tissue, potentially a valuable improvement for bioimaging.

Reported in Light Science & Applications, the approach could eventually help to reduce the need for surgery or biopsies, according to the team.

The method exploits the property called orbital angular momentum (OAM), a parameter relating to the spiral phase of a light beam.

OAM beams with their tailored spatial structure have previously been applied to a number of different applications, including astronomy, microscopy, imaging, metrology, sensing and optical communications.

"Despite the technical challenges, shaped OAM light has emerged as one of the most exciting front lines of contemporary research," commented the Aston project in its published paper. "OAM-based twisted light holds great potential for various biomedical applications."

The appeal of OAM light for bioimaging is down to its altered behavior when interacting with scattering media and the potential for significant increases in transmission through living tissues, a complex topic which the Aston team under Igor Meglinski set out to investigate.

The Meglinski lab has already studied other ways that light polarization can be exploited for bioimaging purposes, such as the detection of biomarkers from cancer in blood samples via liquid biopsies.

Significant leap forward in glucose monitoring

The research team conducted a series of controlled experiments, transmitting OAM beams through media with varying levels of turbidity and refractive indices to model the effects of biological systems. Detection techniques including interferometry and digital holography captured and analyzed the light's behavior.

Results showed that OAM can indeed retain its phase characteristics even when passing through highly scattering media, unlike regular light signals. This means it can detect extremely small changes "with an accuracy of up to 0.000001 on the refractive index, far surpassing the capabilities of many current diagnostic technologies," said the project in its paper.

"Our findings bridge a crucial gap for the biophotonics and OAM communities by demonstrating how OAM light, even in environments characterized by a high optical depth, retains its helical phase structure. This behavior underscores the potential of OAM light for probing biological tissues in the multiple scattering regime."

The researchers believe that the findings pave the way for a range of transformative applications, and adjusting the initial phase of OAM light should be valuable in fields such as secure optical communication systems and advanced biomedical imaging.

"By showing that OAM light can travel through turbid or cloudy and scattering media the study opens up new possibilities for advanced biomedical applications, for example more accurate and non-invasive ways to monitor blood glucose levels, providing an easier and less painful method for people with diabetes," noted Igor Meglinski.

"The potential for precise, non-invasive transcutaneous glucose monitoring represents a significant leap forward in medical diagnostics. A comprehensive understanding of how OAM light interacts with complex scattering environments reinforces its potential as a versatile technology for future optical sensing and imaging challenges."