A. Lens refractive power
B. Luminous intensity
C. Power
D. Distance of heavenly bodies
Submitted by: Mansoor Ahmed Suhag
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.