For a given simple lens, the focal length
can be calculated using the Lensmaker's Equation (also derived from Snell's law):
![$\displaystyle (n_2 - n_1)\left(\frac{1}{r_1} + \frac{1}{r_2}\right) = \frac{1}{f} .$](img399.gif) |
(4.7) |
The parameters
and
represent the radius of curvature of each of the two lens surfaces (front and back). This version assumes a thin lens approximation, which means that the lens thickness is small relative to
and
. Also, it is typically assumed that
, which is approximately true for air.
Steven M LaValle
2020-11-11