Now, lighting panel that mimics a sunny day

Scientists have developed a lighting panel that uses nanoparticles to recreate something close to natural daylight, allowing you to wake up to the sun even on a rainy day.
The panel could also allow for windowless interiors of shopping malls and underground stations to get a dose of blue skies.
The system, developed by Paolo di Trapani at the University of Insubria in Como, Italy, and his colleagues, uses white LEDs as its source.
The LEDs shine through a clear plastic panel studded with nanoparticles that scatter light in the same way as Earth's atmosphere does with sunlight.
Different panels can simulate various outdoor light conditions - from a bright sunny day to a gorgeous sunset or even the brooding skies of a storm, 'New Scientist' reported.

The idea, said di Trapani, is to help "the rapidly increasing fraction of the population who spend more and more of their time deprived of natural lighting".

By peppering a clear polymer with titanium dioxide nanoparticles, the team managed to mimic the physics of Rayleigh scattering, the process by which air molecules scatter the sun's radiation.
Two different sizes of nanoparticles, clustered in different sections of the plastic, separate white light into diffuse "sky light", in which blue wavelengths are dominant, and a bright spot of warm, yellowish light just like direct sunlight.
The prototype panel, which is 1.8 metres long and 85 centimetres wide, was unveiled last month at a lighting exhibition in Frankfurt, Germany.