Numerical aperture

Numerical aperture is like a magic number that helps light get into a piece of equipment called a microscope.

Think of a microscope as a tiny room with a door that only allows light to enter. The door is called the lens, and it controls how much light can come in. Numerical aperture is like the lens's secret code that tells the light how much it can come in.

If the numerical aperture is high, that means the lens is allowing a lot of light to get into the microscope. This is helpful because the more light there is, the more the microscope can see.

But if the numerical aperture is low, that means the lens is letting in less light. This is not as helpful because the microscope will not be able to see as much.

So, numerical aperture is like a special code that helps light get into a microscope and shows us more detail in our samples.