According to a newly discovered property of wave propagation may lead to a novel way to improve the resolution of virtually all optical technologies everything from microscope lenses to telecommunications, laser-based lithography, biological and astronomical imaging. The study was Published in Proceedings of the National Academy of Sciences of the USA (PNAS), this study shows that scientists should re-examine this belief and revisit their design strategies.
Scientists have discovered a new property of wave propagation that leads to an all-new way to improve the resolution of virtually all optical technologies, including microscope lenses, telecommunications, laser-based lithography, biological and astronomical imaging. All these systems transmit information and energy through wave propagation.
Resolution Of Image
Researchers at the Center for Soft and Living Matter, within the Institute for Basic Science (IBS, South Korea) have discovered that if light passes through asymmetric apertures, astigmatism arises and can degrade image resolution. Having identified this previously-unsuspected problem, the researchers showed how to remedy it.
To avoid this focusing defect, artificial lenses are optimally designed to change the shape of the light wavefronts from planar into perfectly spherical wavefronts, because it is believed that spherical wavefronts necessarily focus at their unique center of curvature.
Examples of wave propagation are circular waves created by a pebble dropped into a pond. The exact point where the pebble hits the water determines the position and the shape of the waves. If you could go back in time, those circular waves would refocus on the initial impact point precisely, because the information on the point location is not lost during wave propagation.
This 2D example can be extended to a 3D situation, where waves are spherical and refocus exactly at the center of the sphere. However, in real life, one generally focuses light from one side, along with some direction and not from all directions, and the ideal picture of focusing from a full circle or a full sphere is never exactly relevant.
Point Scanning Microscopy
The team applied the idea to improve a technique called line-temporal focusing microscopy, which makes use of a naturally asymmetric input beam. As LTFM is a method used to visualize deep biological structures, the researchers tested their focal shift correction strategy with mouse lung tissues. An unprecedented resolution was obtained, that even outperformed a classical technique called point scanning microscopy (PSM).
Understanding that astigmatism is intrinsic to the broken circular symmetry could help design corrections tailored to the aperture shape, especially in fields such as astronomy, telecommunication, or with ultrasounds, where non-circular apertures cannot be avoided.
In the future, they plan to apply aperture-induced astigmatism to even more complex information transfer technologies. They believe it can contribute to design better systems in synthetic microscopic eyesight, telecommunications, and even microwave devices.