- #1
zheng89120
- 149
- 0
Homework Statement
An optical system consists of two identical lenses; the focal length of each lens is fo (where fo) is positive). The lenses are separted by a distance d. Denote the focal lenths of the lens assembly by f and f'.
a) Show that for any separation of the lenses f = f'
b) Find the separation between lenses that leads to the focal length of the lens assembly being equal to 2fo
Homework Equations
thin lens equations, refracting/travelling matrices?, f' = -1/a21
The Attempt at a Solution
a) I did the intuitive approach: a set of rays coming from either end of the 2 lense assembly will experience the same assembly, and hence converge to the same focal lengths (after exiting assembly at either end)
b) I used the matrix method with the matrix for thin lense being (1, 0; -1/fo, 1)
anyways, after some calculation... I got: d = (3/2)fo (correct?)
Last edited: