the straight line passing through the geometrical centre of a lens and joining the two centres of curvature of its surfaces. Sometimes the optical axis of a lens is called its principal axis. The path of a light ray along this axis is perpendicular to the surfaces and, as such, will be unchanged. All other ray paths passing through a lens and its optical centre (the geometrical centre of a thin lens) are called secondary axes. The optical axis of a curved mirror passes through its geometric centre and its centre of curvature.
Learn more about optical axis with a free trial on Britannica.com.
|a stew of meat, vegetables, potatoes, etc.|
|a chattering or flighty, light-headed person.|
Dictionary.com presents 366 FAQs, incorporating some of the frequently asked questions from the past with newer queries.