Do you wonder how to write a text or images with UV-LEDs? Build your own Arduino-based phosphorescent display and display a text on it. What we need to make the text visible is a rotating drum, coated with a phosphorescent film and illuminated with light using UV diodes. The rotational speed of the drum corresponds approximately to the re-emission time of the phosphorescent film and thus a new text or image can be displayed for each new rotation of the drum.
The photonics principles used are light absorption and light emission. The different wavelengths of light (visible and non-visible ones) are also introduced.