Question

define reduction diopter ​

Answer 1

A dioptre (British spelling) or diopter (American spelling) is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres. (1 dioptre = 1 m−1.) It is thus a unit of reciprocal length. For example, a 3-dioptre lens brings parallel rays of light to focus at ​1⁄3 metre.

Answer 2

Explanation:

A dioptre (British spelling) or diopter (American spelling) is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres. (1 dioptre = 1 m−1.) ... For example, a 3-dioptre lens brings parallel rays of light to focus at 1⁄3 metre.