Biomedical Engineering Reference
In-Depth Information
LATERAL (TRANSVERSE) CHROMATIC
ABERRATION
Lateral chromatic aberration can be a consideration in the design of certain optical
systems. Figure F-2A shows a lens that has no
longitudinal
chromatic aberration.
The image still suffers from lateral chromatic aberration because each wavelength
results in an image of a different size. Consequently, the image has colored fringes.
Lateral chromatic aberration can be minimized with an optical system consist-
ing of two lenses of the same constringence that are separated by the distance
d
, as
defined below:
′
′
2
f
+
f
1
d
=
2
Figure F-2B shows a lens system with minimal lateral chromatic aberration.
Note that the amount of longitudinal aberration is substantial. Depending on the
intended use of an optical system, it may be a priority either to minimize longitudi-
nal chromatic aberration or to minimize lateral chromatic aberration.
As discussed in Chapter 15, lateral chromatic aberration can reduce image quality
when a patient views through a point significantly removed from the optical axis
of a spectacle lens that has a low Abbe value (Fig. 15-16). If a lens material with a
low Abbe number, such as polycarbonate, is prescribed, it may be important for the
optical axis to be in approximate alignment with the patient's pupil, particularly in
higher prescriptions.
