Zone plate

Well, remember when you played with a magnifying glass and noticed how the sunlight passing through it could be focused to make things look bigger? A zone plate is a special kind of lens that works in a similar way.

But instead of using just one piece of glass, a zone plate is made up of a series of alternating rings of clear and dark material, like a bullseye target. When light passes through the zone plate, the different rings bend and focus the light in a certain pattern, making a tiny spot of light called a "focus" where all the light rays come together.

This special pattern of light can be used in a lot of scientific and industrial applications, like making very detailed images of tiny things or measuring the thickness of materials. It's like having a super power to zoom in and really see the tiniest details!