A day before researchers announced that they had successfully used nanoscale inkjet technology to create a color image small enough to fit in the cross-section of a human hair, a different team in Denmark shared details of its new laser-printing tech. It could allow this entire article to be printed within that same area.

The laser technology from researchers at the Technical University of Denmark allows for printing at a resolution of 127,000 DPI, more than five times the resolution of comparable inkjet technology. By comparison, most commercially-printed pages are just 300 DPI.

Printing such finely-detailed microscopic type or images requires a custom nanoscale-structured surface split into rows and columns with a diameter of just 100 nanometers each. The surface is coated in a layer of aluminum 20 nanometers thick that can be precisely melted and deformed when hit with a laser pulse, changing the color of each cell.

The Mona Lisa, laser-printed at nanoscale(Credit: DTU)

"Every time you make a slight change to the column geometry, you change the way it absorbs light. The light which is not absorbed is the color that our eyes see," explains Professor N. Asger Mortensen, one of the co-authors of a paper on the new technique. "If the column absorbs all the blue light, for example, the red light will remain, making the surface appear red."

Professor Anders Kristensen, another co-author, says the technology could be used for more practical applications than printing things far too small for the human eye to distinguish.

An illustration of how individual cells are deformed using a laser to change their color(Credit: DTU)

"It will be possible to save data invisible to the naked eye," he states. "This includes serial numbers or bar codes of products and other information. The technology can also be used to combat fraud and forgery, as the products will be labelled in way that makes them very difficult to reproduce. It will be easier to determine whether the product is an original or a copy."

The technology could also be used on a larger, visible scale for things like personalizing mobile phones or printing instrument panels for vehicles. The Danish researchers have patented the innovation and hope to develop it to replace the current generation of more conventional laser printers.

The research paper was recently printed in the journal Nature Nanotechnology.

Source: DTU

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