Okay kiddo, have you ever looked at a rainbow and noticed how it has different colors? That's because the sunlight gets diffracted, which means it gets separated into its different colors.
A diffractometer is a special tool that scientists use to study the structure of materials. The diffractometer works by shining a beam of light or other type of radiation at the material and measuring how the radiation scatters or diffracts off of it.
The pattern of the scattered radiation tells the scientists something about how the atoms in the material are arranged. Just like how looking at the colors of a rainbow can tell us about the light that makes it up.
The diffractometer is kind of like a camera that takes pictures of the scattered radiation pattern. Scientists then analyze these patterns to figure out what the material is made of and how it behaves.
So, in short, a diffractometer is a tool that helps scientists see what things are made of by studying how radiation scatters off of them.