Transcript Diagram

Spherical Aberration
Definition:
Rays emanating from an object point
that are incident on a spherical
mirror or lens at different distances
from the optical axis, after reflection
or refraction, either intersect, or
appear to intersect, at different
positions.
Diagram:
Diagram:
Diagram:
Diagram:
Ideal
situation
Real
situation
Diagram:
Photo:
Negative ….
aberration
zero ….
aberration
Positive ….
aberration
Correction:
Use “stops” so that only nearly
paraxial rays (i.e. rays near the
optical axis) get through to the
lens (or spherical mirror).
Correction:
Combine positive and negative lenses in an
arrangement so that the …. aberration from one
tends to cancel that from the other.
chromatic Aberration
Definition:
It results because the index of
refraction of a material differs for
different wavelengths. Since the focal
length of a lens is dependent on the
index of refraction of the lens material,
focal lengths and image positions differ
for different wavelength components
of the light used in the optical system.
Definition:
is limited only to lenses.
Mirrors cannot cause this
type of aberration.
Diagram:
Diagram:
Diagram:
Off-axis: lateral
Photo:
Correction:
Use multiple refractive elements of opposite
powers.
Coma Aberration
Definition:
It derives its name from the cometlike
appearance of the image of an object point
located just off the lens axis.
Diagram:
Diagram:
Diagram:
Photo:
Astigmatism Aberration
Definition:
It is an aberration where rays that
propagate in two perpendicular planes have
different foci.
It is an optical aberration in which, instead
of rays converging to a single focus, they are
caused to focus to two lines at right angles,
separated by an interval.
Diagram:
Correction:
Correction involves the use of
planocylindrical, spherocylindrical,
or spherotoric lenses.
Field curvature Aberration
Definition:
In general, a plane object at right angles to
the axis of an optical system will not give
rise to a plane image. Instead, the image
would lie on a paraboloid surface known as
the Petzval surface.
Diagram:
Photo:
Distortion Aberration
Definition:
Angular deviation of the wavefront
destroying the linear relation between
dimensions in object and image.
Diagram:
None
Pincushion
barrel
Photo: