Definition

Relating to optical systems that have been adjusted to eliminate spherical aberration, which is a distortion that occurs when light rays entering a lens do not converge at a single point.

Example

The aplanatic lens design ensures that images are sharp and clear by correcting for spherical aberration.

Conversation

I just got a new telescope and it's supposed to be aplanatic.

That sounds cool! Does that mean it won't distort the images?

Exactly! It corrects for spherical aberration, so I can see the stars clearly.

Nice, I can't wait to look through it and see how sharp the details are!

Synonyms & Antonyms

Root Explanation

Aplanatic → It is formed from "a-" (meaning without) and "planatic" (from Greek "planasthai", meaning to wander). The term describes a lens or optical system that does not produce spherical aberration, hence it is 'without wandering' in terms of focus.

Memory Tip

Think of 'without' ('a-') any 'wandering' ('planasthai') in focus — that's why aplanatic refers to a lens that keeps light rays from diverging.

Visually Confused Words