• Support PF! Buy your school textbooks, materials and every day products Here!

Optical Path Length

  • Thread starter kpl
  • Start date
kpl
6
0
1. Homework Statement

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

2. 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

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
 

Answers and Replies

243
1
I think I remember doing this problem a while back - if I'm right, the derivation is not simple. If nobody replies, give me some time to recall my memory...
 
243
1
I don't know if you've managed to do the problem but you were on the right track.

You asked whether or not you subtract the expression for r1 from r2 - that depends if you represented the reflected light ray's velocity as negative or if you've subtracted the entire reflected path. Either way should be fine, though I would probably stick with representing the reflected velocity as negative.
 

Related Threads for: Optical Path Length

Replies
3
Views
2K
  • Last Post
Replies
1
Views
1K
Replies
0
Views
2K
Replies
1
Views
716
Replies
2
Views
4K
Replies
0
Views
589
Replies
1
Views
397
Replies
5
Views
1K
Top