The formula to calculate the SAG is:
\[ SAG = R - \sqrt{R^2 - \left(\frac{D}{2}\right)^2} \]
Where:
Let's say the radius of curvature (R) is 10 units and the diameter of the curve (D) is 6 units. The SAG would be calculated as follows:
\[ SAG = 10 - \sqrt{10^2 - \left(\frac{6}{2}\right)^2} = 10 - \sqrt{100 - 9} = 10 - \sqrt{91} \approx 0.46 \]
So, the SAG is approximately 0.46 units.
SAG is a term used in optics to describe the distance or length between the vertex point along the curve and the center point of a line drawn perpendicular to the curve from one edge to the other. This is used mostly in optics when dealing with convex or concave curvatures of lenses.