1/m
reciprocal meter
Optical powerexact by definition
The reciprocal metre is the dioptre written the way physics writes it, exactly equal to it. Optical power is one over the focal length in metres, so a lens of focal length 0.5 m has a power of 2 m⁻¹, which optometry calls 2 dioptres. The equality is exact, being a naming difference rather than a conversion.
Watch out: Optical power in reciprocal metres is not the same quantity as wavenumber, which shares the unit and describes cycles per unit length, nor as an attenuation coefficient. Reciprocal metres appear in several unrelated quantities and the name matters more than the unit.
| 1 1/m | 1 dpt |
Solvers that use optical power