A new form of high-resolution 'printing' which could be developed for anti-counterfeiting measures in banknotes has been discovered by scientists.
The nanoscale printing breakthrough could also have implications for data storage and digital imaging.
Engineers from the University of Glasgow have developed nanoscale plasmonic colour filters that display different colours depending on the orientation of the light which hits it.
This new technique allows the 'printing' of two entirely different, but exceptionally detailed, full-colour images within the same surface area.
The team, from the university's School of Engineering, have demonstrated their technique with several examples, including a nanoscale image which shows the university's crest when the light reaches it in one orientation, and an image of the university tower when the orientation of the light is reversed.
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"We've discovered that if we make colour pixels from tiny cross-shaped indents on a strip of aluminium film, the colour they display becomes polarisation-dependent, allowing us to encode two colours into a single pixel, and then select which colour is displayed by shining different polarisations of light at the surface," said biomedical engineering lecturer Dr Alasdair Clark, lead author of the research paper.
"By changing the size and shape of the nanoscale indent, we can create a wide range of different colours at very high resolutions."
Instead of relying on dyes and pigments, as in traditional printing, structural colour uses specially structured nanomaterials to render colours.
These allow for much higher-resolution prints which do not fade over time.
While a typical printed image in a magazine might consist of around 300 coloured dots per inch of page, or 300 DPI, a page 'printed' with structural colour techniques could reach a resolution of 100,000 DPI or more.
