Lecture 7
1
© Jeffrey Bokor, 2000, all rights reserved
Lecture 7
Wave Front Aberration
In a waveoptics picture, the thin lens is represented by phase delay.
Which gives Gaussian
imaging. Aberrations modify
. A spherical lens only gives this
in the parax
ial approximation.
•
For a complex optical system, we can collect the effects of all the lenses and represent them as a phase
delay in the exit pupil. Usually, we subtract the quadratic phase to find the aberration. The residual is
called the wave front error; or wfe
usually depends on the field coordinate. In other words, the aberrations can vary depending on
where you are in the field of view.
Expressed in this way, the primary aberrations are written as:
Spherical aberration:
Coma:
Astigmatism:
Field Curvature:
Distortion:
x, y
k
–
x
2
y
2
+
2

k
x, y
–
==
x, y
x
2
y
2
+
2
f
–W
x
,
y
+
=
Aberration wfe
x, y
ideal wave front
aberrated wavefront
W(x,y)=
A
s
4
: is normalized radial coordinate in the pupil
: image height
h
A
c
3
h
cos
A
a
2
h
2
2
cos
A
d
2
h
2
A
t
h
3
cos
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2
© Jeffrey Bokor, 2000, all rights reserved
Monochromatic Aberrations:
All of the preceding discussion refers to aberrations that do not depend on
wavelength.
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 Spring '09
 chromatic aberration, spherical aberration, Jeffrey Bokor

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