Transparent Laser Displays Enabled by Optical Resonances

Technology      

This invention is the result of developing transparent displays that operate by scattering visible light from resonant nanoparticles with narrowband scattering cross sections and small absorption cross sections. More specifically, projecting an image onto a transparent screen doped with nanoparticles that selectively scatter light at the image wavelength(s) yields an image on the screen visible to an observer. Because the nanoparticles scatter light at only certain wavelengths, the screen is practically transparent under ambient light. Exemplary transparent scattering displays can be simple, inexpensive, scalable to large sizes, viewable over wide angular ranges, energy efficient, and transparent simultaneously.  

Problem Addressed

A number of different transparent displays have been developed, each suitable for a subset of the applications. The simplest type is the head-up display that projects into the viewer’s eyes through reflecting the image off a beam splitter. Head-up displays are well suited to certain occasions, but the narrow viewing angle limits the position of the viewer. Diffusive screens achieve wider viewing angles by light scattering; such screens do not have wavelength selectivity, so stronger scattering is necessarily accompanied by lower transparency. Frequency-conversion screens achieve higher transparency using molecules that convert the projected ultraviolet light to visible light ,or infrared light to visible light; the conversion, however, is challenging to implement with high efficiency. Instead of relying on projection, one can also make electronic flat panel displays transparent, for example by combining organic light-emitting diodes with transparent electronics. There is active research in developing this type of transparent displays, but scaling to large display sizes remains challenging.  

Advantages

• Transparent scattering displays can be simple, inexpensive, scalable to large sizes, viewable over wide angular ranges, energy efficient, and transparent simultaneously
• Windows can be retrofitted with the film; therefore, there is no need to replace the window
• The technology is compatible with existing commercial LED/laser projectors  

Publications

Transparent Displays Enabled by Resonant Nanoparticle Scattering. Nature Communications 5, (January 21, 2014): Article 3102.