Quantitative imaging could create a bright future for advanced microscopy

The unique properties of quantum physics could help solve a long-standing problem that prevents microscopes from producing sharper images on the smallest scales, researchers say.

The breakthrough, which uses entangled photons to create a new way to correct image distortion in microscopes, could lead to improved classical microscopic imaging of tissue samples to help advance medical research.

It could also lead to new developments in quantitative enhanced microscopy for use in a wide range of fields. The team's paper has been published titled “Adaptive Optical Imaging with Entangled Photons.” Sciences. Researchers from the University of Cambridge and the Casteler-Brussel Laboratory in France also contributed to the research.

Microscopes have been invaluable tools for scientists for hundreds of years. Advances in optics have enabled researchers to resolve more detailed images of the underlying structures of cells and materials.

However, as microscopes have evolved in complexity, they have begun to encounter the limits of conventional optical technology, where even small imperfections in the image-resolving elements can produce blurry images.

Currently, a process called adaptive optics is used to correct image distortions caused by aberrations. Aberrations can be caused by small defects in lenses and other optical components or by imperfections in the sample under the microscope.

The key to adaptive optics is the “guide star” – a bright spot identified in the sample under a microscope that provides a reference point for detecting aberrations. Devices called spatial light modulators can shape light and correct these distortions.

Relying on guide stars poses problems for microscopes that image specimens such as cells and tissues that do not contain bright spots. Scientists have developed starless adaptive optics using image processing algorithms, but these algorithms can fail for samples with complex structures.

In the new paper, researchers from the United Kingdom and France demonstrate how they use entangled photons to sense and correct aberrations that typically distort microscopic images. They call this process quantum-assisted adaptive optics.

The paper describes how their new technique was used to correct distortion and retrieve high-resolution images of biological test specimens – the honey bee's mouthpiece and leg. They also demonstrate aberration correction for samples with 3D structures, a situation in which classical adaptive optics often fails.

They used entangled photon pairs to illuminate the samples, allowing them to take a conventional image and measure quantum correlations at the same time.

When entangled photon pairs experience diffraction, their entanglement – ​​in the form of quantum correlations – becomes degraded. The way these quantum correlations are decomposed actually reveals information about the anomalies and allows them to be corrected using sophisticated computer analysis, the researchers show.

The information contained in the correlations allows the aberrations to be accurately characterized, which can then be corrected using a spatial light modulator. The research demonstrates that correlations can be used to produce sharper, higher-resolution images than traditional microscopy techniques.

Patrick Cameron, from the University of Glasgow's School of Physics and Astronomy, is first author on this paper. “Complex samples such as biological tissue can be a challenge for imaging using traditional methods of microscopy, where the bright star technique can fail because there are rarely normal bright spots in human or animal tissue,” he said.

“This research shows that quantum entangled light sources can be used to examine samples in ways that are more difficult, if not impossible, using conventional microscopy. Identifying and correcting aberrations and distortions using entangled photons has allowed us to produce sharper images without having to use light.” The Need for a Star guide.”

Dr Hugo Devin began working in research at the School of Physics and Astronomy at the University of Glasgow before moving to the Paris Institute of Nanoscience at the Sorbonne University, where he is now based. Dr Devine, the final author of the paper, said: “This new technique can be widely applied to all types of conventional optical microscopes to help improve imaging of a wide range of samples. We have demonstrated its effectiveness on biological samples, suggesting that it could be used in medical sectors.” and biology in the future.

“It can also be applied to the emerging field of quantum microscopy, which has enormous potential to produce images beyond the limits of classical light.”

The team still has to overcome some technical hurdles before the technique can be widely adopted in optical microscopes.

Professor Daniel Fassio, who leads the Extreme Light Research Group at the University of Glasgow, is a co-author of this paper. “The next generation of cameras and light sources will likely help improve the speed of image processing using this technology,” he said. “We will continue to work on improving and developing the process and look forward to finding new real-world applications for image analysis.” Advanced microscopy as we move forward.”