(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Derive the optical length of the incident light being reflected back to the surface of the lens with radius r1.

2. Relevant 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

3. 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

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# Homework Help: Optical Path Length

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