There is a very good chance that we are all familiar with light being used to draw on a solid surface, as this is done in LCD screens. What we are not so familiar with though is drawing in a liquid with light, likely because it has never been accomplished before. Researchers at the University of Helsinki however, have successfully created a solution that will change in appearance, when exposed to light.
When first mixed into water or some alcohols, the new photosensitive polymer does not dissolve, and blocks light from passing through it. Shining a 365 nm laser on it though changes the polymer chain, causing it to dissolve into the solution, and become transparent. This effect can last for hours, depending on variables such as the concentration of the solution.
Exactly what this discovery may lead to is hard to guess at this point. A liquid display would be pretty cool though.
Source: University of Helsinki