system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't I focus blue LED light?
gpt
You know how a prism can spread white light into all the bands of visible light?

This is caused by chromatic aberration where different colors (wavelengths) of light interact differently when going through the prism. If the prism was switched to a single lens, chromatic aberration causes different wavelengths of light to focus at different distances from the lens.

Your eye is an optical element as well. Due to chromatic aberration, blue light is just slightly out of focus on your retina while other colors may focus perfectly.