Word of the Day
17 May 2026
spherometer
A device used to measure the curvature of a surface, such as a lens.
Why this one
The name is literal: it reads how far a surface departs from flat across a known ring of contact, and that sagitta converts to a radius. Opticians reach for one because a curve is easier to measure as a depth than as an arc.
In use
Put it on the spherometer before you polish any further, the radius came back short on the last two blanks.
Written by our editors to show how the term is used, not a recorded quotation.Sources
- Definition sourceWiktionary