A transparent display based on the reflection of laser light by silver nanoparticles is reported this week in Nature Communications. The display, which could be used for augmented reality devices where your view of the world is enhanced using digital images overlaid onto real ones, is easy to manufacture and offers a wide viewing angle.
Silver nanoparticles have narrow optical resonances that cause them to scatter light of a specific wavelength, and are almost transparent at other colours. Chia Wei Hsu and colleagues have now embedded such nanoparticles into a polymer film. They find that if the image of an object is projected onto the screen by a laser tuned to the colour of this resonance, the light will be reflected by the nanoparticles, making the image visible, whereas other light passes through. By using nanoparticles sensitive to the three primary colours, the team could create a full-colour display. Initial tests showed that a single-colour display performed well and the colour of objects behind the screen changed only slightly as a result of the light scattering.
Although the use of lasers may limit mass-market applications, such films could be used as wind-screen displays in cars or airplanes, for example.