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# SAG Calculator

Determine sag of a surface based on radius of curvature and diameter. Calculator can be used to provide simple mechanical parameters that simplify specification of optical components. Commonly used for lenses and mirrors.

Sag (mm): --

## Equation and Corresponding Legend

$$\text{SAG} = R - \sqrt{R^2 - \left( \frac{D}{2} \right)^2}$$
 R Radius of Curvature D Diameter