- #1
kpl
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Homework Statement
Derive the optical length of the incident light being reflected back to the surface of the lens with radius r1.
Homework Equations
i have assumed that the surfaces can be given as r^2 = y^2+z^2
there are 2 surfaces of the lens with radii r1 and r2
The Attempt at a Solution
is it simply subtracting the expression for r1 from the expression for r2?
i have attemped using Fermats principle but cannot get very far