Hi,

The answer is Dioptre.

Dioptre is a unit of measurement of the optical power of lens or curved mirror, which is equal to the reciprocal of the focal length measured in meters.

So, basically 1 DIOPTRE is equal to 1 m's power -1.

I hope this will help you.

Thank you

Hello Aspirant,

See power of lens is defined as reciprocal of its focal length and focal length's SI Unit is metre(m) so as per definition of Power its SI Unit is Dioptre(D) which is equally known as inverse of meter or m^-1.

I hope this information helps you.

Good Luck!!