Difference between revisions of Diopters
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Diopter is a measure of the [https://en.wikipedia.org/wiki/Optical_power optical power] P of a [[lens]] (or mirror) and is equal to the reciprocal of [[focal length]] in meters. The most common unit symbol for diopters is dpt, D, or m<sup>-1</sup>. | Diopter is a measure of the [https://en.wikipedia.org/wiki/Optical_power optical power] P of a [[lens]] (or mirror) and is equal to the reciprocal of [[focal length]] in meters. The most common unit symbol for diopters is dpt, D, or m<sup>-1</sup>. | ||
<math>P = \frac{1}{f} | <math>P = \frac{1}{f} = -\frac{1}{d}</math> | ||
* In [[EM]], we use the [[cm measurement]] to calculate diopters needed to correct [[refraction]] of the eye. If you can see 50 cm clearly, your diopters will be <math>-\frac{1}{0.50}=-2 dpt</math>. | * In [[EM]], we use the [[cm measurement]] to calculate diopters needed to correct [[refraction]] of the eye. If you can see 50 cm clearly, your diopters will be <math>-\frac{1}{0.50}=-2 dpt</math>. | ||