Innovative Breakthrough: Physicists Push the Boundaries of Microscopy Beyond Diffraction Constraints
A team of researchers hailing from the University of Sydney has pioneered a revolutionary approach to achieving super-resolution imaging without relying on a super lens. This breakthrough promises significant advancements across a spectrum of disciplines, encompassing medical imaging and the authentication of artworks.
This groundbreaking technique bears immense potential for applications in medical diagnostics and advanced manufacturing.
Ever since Antonie van Leeuwenhoek’s discovery of the microcosmic realm through a microscope in the late seventeenth century, humanity has relentlessly striven to delve deeper into the infinitesimally small dimensions of the universe.
However, conventional optical methods impose physical limitations on the degree to which we can scrutinize an object. This limitation is known as the ‘diffraction limit,’ rooted in the wave-like nature of light. Essentially, it dictates that a focused image can never be smaller than half the wavelength of the light employed for observing an object.
Efforts to circumvent this constraint through the use of “super lenses” have consistently encountered a formidable obstacle—substantial visual losses rendering the lenses opaque. Now, physicists from the University of Sydney have unveiled a new avenue to achieve superlensing with minimal losses, surpassing the diffraction limit by nearly fourfold. Remarkably, their success hinges on eliminating the super lens altogether.
This groundbreaking research has been detailed in the latest issue of the esteemed journal Nature Communications, dated October 18.
Implications for Science and Beyond
The ramifications of this achievement extend far and wide, as it promises to empower scientists in the realm of super-resolution microscopy. The applications span diverse domains, including cancer diagnostics, medical imaging, archaeology, and forensics.
Dr. Alessandro Tuniz, the lead author of this research and a member of the School of Physics and University of Sydney Nano Institute, elucidates, “We have now developed a practical way to implement superlensing, without a super lens.”
Scientists have harnessed this novel superlens technique to scrutinize an object of mere 0.15 millimeters in width, employing a virtual post-observation approach. The object, represented as ‘THZ’ denoting the ‘terahertz’ frequency of light utilized, is displayed through initial optical measurement, standard lensing, and finally, superlensing.
Previous attempts had ventured into crafting super lenses using unconventional materials. Nonetheless, most materials exhibited excessive light absorption, rendering the super lens impractical.
Dr. Tuniz expounds, “We have surmounted this challenge by executing the superlens operation as a post-processing step on a computer, subsequent to the measurement itself. This yields a ‘truthful’ image of the object by selectively amplifying evanescent, or vanishing, light waves.”
Practical Applications and Future Prospects
Co-author Associate Professor Boris Kuhlmey, also affiliated with the School of Physics and Sydney Nano, emphasizes, “Our method could find application in ascertaining moisture content in leaves with unparalleled resolution or prove invaluable in advanced microfabrication techniques, particularly non-destructive assessment of microchip integrity.”
Furthermore, this method possesses the potential to unveil concealed strata in artworks, potentially aiding in uncovering instances of art forgery or hidden artworks.
Traditionally, endeavors in superlensing have concentrated on obtaining high-resolution information in close proximity to the object. However, the rapid decay of this invaluable data with distance and its submergence amidst low-resolution data, which decays less rapidly, has posed a conundrum. Approaching the object too closely distorts the resultant image.
Associate Professor Kuhlmey elaborates, “By relocating our probe farther away, we can preserve the integrity of high-resolution information and employ a post-observation technique to sift out low-resolution data.”
The research was conducted using light in the terahertz frequency range, within the millimeter wavelength spectrum, situated between the realms of visible and microwave frequencies.
Associate Professor Kuhlmey concludes, “Operating within this challenging frequency range presents opportunities for gleaning crucial insights into biological samples, such as protein structure, hydration dynamics, and applications in cancer imaging.”
Dr. Tuniz emphasizes, “This technique serves as the initial step towards obtaining high-resolution images while maintaining a safe distance from the object, free from distortion. We anticipate that practitioners in high-resolution optical microscopy will find this technique of significant interest.”
Reference: “Subwavelength terahertz imaging via virtual superlensing in the radiating near field” by A Tuniz and B Kuhlmey, dated October 18, 2023, Nature Communications.
DOI: 10.1038/s41467-023-41949-5
Funding: Australian Research Council
Table of Contents
Frequently Asked Questions (FAQs) about Superlensing
What is the diffraction limit in microscopy?
The diffraction limit in microscopy is a fundamental constraint imposed by the wave-like nature of light. It dictates that the smallest resolvable details in an image cannot be smaller than half the wavelength of the light used for observation.
How did the researchers at the University of Sydney achieve super-resolution imaging without a super lens?
The researchers achieved super-resolution imaging by removing the need for a super lens altogether. They developed a technique that involves placing the light probe far away from the object and collecting both high- and low-resolution information. This approach avoids interference with high-resolution data, which was a challenge in previous methods.
What are the potential applications of this superlensing technique?
This superlensing technique has a wide range of applications. It can be used in fields such as cancer diagnostics, medical imaging, archaeology, forensics, and advanced microfabrication. Additionally, it could be valuable for revealing hidden layers in artwork, aiding in art authentication and forgery detection.
How does this technique differ from previous attempts to achieve superlensing?
Unlike previous attempts that tried to create super lenses using novel materials, this technique performs the superlens operation as a post-processing step on a computer, after the measurement itself. This approach selectively amplifies evanescent light waves, allowing for super-resolution imaging without the need for specialized materials.
What is the significance of operating in the terahertz frequency range?
Operating in the terahertz frequency range offers the potential to gain important insights into biological samples, including protein structure and hydration dynamics. It can also be applied in cancer imaging, making it a valuable frequency range for various scientific and medical applications.
More about Superlensing
- University of Sydney’s Official Website
- Nature Communications Journal
- Australian Research Council
- Antonie van Leeuwenhoek – Microscope Pioneer
