
14 2. Preliminaries: Definitions and Paraxial Optics
2.4.
TWO-SURFACE REFRACTING ELEMENTS
We now apply the results of Section 2.2 to several systems with two refracting
surfaces, a thick lens, a thin lens, and a thick plane-parallel plate. We first
consider a thick lens, a lens in which the second refracting surface is distance d to
the right of the first surface.
2.4.a. THICK LENS
A schematic cross-section of a thick lens is shown in Fig. 2.5. If we assume the
lens has index n and is located in air, then w^ = «^ ^ 1, and n\ =
n2
= n.
Applying Eq. (2.2.5) to each surface gives
R.
•^2
R,
(2.4.1)
where ^2 =
^^i
- d.
With this system we find onl ...