LED lights simulate natural light and you can also see the blue sky indoors

Lighting technology has made great progress in the past few years, but people still cannot use lights to simulate the effect of natural sunlight well. Today, this problem has finally achieved a breakthrough: a group of Italian scientists use panels coated with special nanoparticles to scatter white LED light sources, thereby creating a clear "blue sky" at any time, in any weather, or even in a dark room without windows.
Paolo di Trapani, University of Insubria, Como Campus, Italy Trapani and his colleagues used white LEDs as the light source and let the light pass through a polymer transparent panel attached with titanium dioxide nanoparticles - these tiny particles that we cannot see with the naked eye can scatter the LED light in the same way that the earth's atmosphere scatters sunlight. The two particle sizes attached to different parts of the transparent panel allow the scattered white light to present two effects at the same time, one is a "blue sky", and the other is a yellow-white bright spot similar to the sun shining directly on the head.
　　If you replace the “blue sky” panel with a different panel, you can also simulate the light of the natural environment such as colorful sunsets, rainy weather, and so on.
　　Most of the previous research on artificial sunlight has focused on making the spectrum of light consistent with that of sunlight, but the interaction between sunlight and the atmosphere cannot be ignored in order to give people a more natural feeling, and the technology adopted by Trapani and his team takes this factor into account first.
　　The existing panel prototype, which is 1.8 meters long and 0.85 meters wide, made its debut at the International Lighting Fair in Frankfurt, Germany, last month, and Trapattoni plans to bring the panel to market through CoeLux, a company independent from the University of British Sabria, with the goal of achieving mass production within the next year or two.