
292 OPTICS FOR ENGINEERS
and for the pair of lenses acting as an imaging system,
q
4
=
Aq
0
+B
Cq
0
+D
=
−q
0
+0
0 −1
= q
0
. (9.48)
Thus this telecentric 1:1 imaging system preserves the Gaussian wavefront perfectly.
In contrast, let us consider an imaging system consisting of a single lens, f = f
1
/2, used as
an imaging lens, satisfying the lens equation, 1/s + 1/s
=1/f . If we consider a 1:1 imaging
system, the results should be comparable to the problem above with two lenses, assum-
ing f
3
=f
1
. Here, we change the subscripts to letters to minimize confusion, and the matrix
equation is
M
ac
= T
bc
L
b
T
ab
=
12f
01
10
−
1
f
1
12f
01
=
−10
−
1
f
−1
. (9.49)
The only difference between ...