Brillouin scattering

Brillouin scattering is when light waves bounce off tiny vibrations in a material, like sound waves in a bell. Imagine you're playing with a bell and hitting it gently. The bell will start to vibrate and make sound waves that travel through the air. Light waves can also bounce off these sound waves, just like you can bounce a ball off a wall.

When light waves bounce off sound waves in a material, they change their direction and their color slightly. This is because the sound waves are moving the material around, stretching and squeezing it, and this changes the way light travels through it.

Scientists can use these slight changes in light waves to study the properties of materials, like how stretchy they are or if they have any defects. They shine a laser at the material and look at the light that bounces back. By analyzing this light, they can learn a lot about what's going on inside the material.

Overall, brillouin scattering is a way for scientists to use light waves to get information about materials and how they behave. It's kind of like listening to a bell to learn how it works!