Made of gold aluminum, black platinum and green silver with a laser machine

By using a tabletop laser, the University of Rochester optical scientists have turned pure aluminum into yellow, green, gray and other colors. All the tested metals can also change color like that, including platinum, titanium, tungsten, silver and gold.

Chunlei Guo, a researcher a year ago, used the maximum laser to change the properties of many metals that made them ink-black, and conducted a similar experiment published in sheets. Applied Physics Letters issued on 1/2/2008. He believes that it is possible to change the properties of any metal so that it bears any color - even five colors, like the wings of a butterfly.

Guo is also an assistant professor of optics at the University of Rochester Optical Institute. According to him, this process changes the characteristics of the inner surface of the metal itself rather than just the outside so the metal will not be blurred or flaky. He said that this possibility was infinite - there was a bicycle factory that used lasers to build bicycles of different colors, and could also create an acid engraving of a family photo. colorful on the door of the fridge, or create a gold engagement ring that is the same color as your fiancée's eyes.

Aluminum gold, green titanium, gold platinum (Photo: Richard Baker, University of Rochester)

Guo said: 'Since the discovery with the black metal last time, we have been able to fully control the phenomenon of metal that only reflects a certain color while absorbing the remaining colors. We were able to make the metal reflect almost any color at will. When we first discovered the process of creating yellow, we did not believe. We work in the lab until midnight trying to find other colors that can be created '.

Guo and his assistant Anatoliy Vorobeyv used extremely short but powerful lasers to change the surface color of the metal, forming the nanoscale structure and the micro level effectively reflecting a specific color thereby causing the metal to has a specific color or a combination of colors.

The study of metallic colors was Guo's next breakthrough after discovering his dark metal in late 2006 when his research team was able to create nanostructures on metal surfaces to absorb all types. light, turning simple metals, such as aluminum, into the darkest metal ever created.

Guo's black metal has a very high absorption of light, and is also ideal for applications that require light absorption properties. According to him, potential applications can make better solar absorbers for advanced tracking technology. The ultra-short but extremely powerful light Guo uses is emitted from a millionth of a millionth of a second (femtosecond laser) pulse laser. Through this process, Guo laser releases energy with all power in North America focused on a point the size of a needle.

The intense energy flow causes the surface of the metal to form a nanostructured structure (dent, small pellet or fibers) that reflects light in different ways according to how the pulsed laser forms those structures . Guo said that because these structures are smaller than the wavelength of light, the way they reflect light depends very much on their specific shape and size. Thanks to the sea laser intensity change, its pulse length and pulse frequency, Guo can control the formation of nanostructures, thereby controlling the color that the metal reflects.

Guo and Vorobyey also made five-color colors thanks to the micro-fiber structure surrounded by nanostructures. Fibers arranged in line create reflections of light with different wavelengths and this ability also differs from different directions. As a result, a small piece of metal can only bring purple from this direction, but it is gray from the other direction or even multiple colors at the same time.

To change color a piece of metal the size of a coin takes up to 30 minutes or more, but scientists are studying technical improvements. Fortunately, although intense light is required, a simple wall socket can also power the femtosecond laser. That means that when the process is improved, implementation will be quite easy.

The new discovery on all of Guo's metals and its immutable results made him believe that the colors of all known metals could be changed. His team is currently working to create the final colors in the rainbow spectrum, including green and red, for single-colored metals.