Re: Diffraction though an aperture with a rounded edge.

Hi,

Using any of the standard optical design programs, including my free
version of KDP2 (version 4.0), just about any aperture shape can be
modelled after which the diffraction point spread function may be
computed and displayed.

The curved edges you refer to simply change the diffraction pattern,
they don't eliminate diffraction.

An apodized aperture, like a radial neutral gray filter going from
100% transmissin to zero transmission as a finction of some distance
from the center of the aperture to the edge will remove a lot of the
diffraction effects but the trade off is loss of energy collected and
it does not remove all the diffraction.

If you have any questions as to how to use KDP2 to model these
effects, send my an email or post a question here and I'll try to post
an answer that can help others as well as you.

Sincerely,

Jim Klein

rgregoryclark@xxxxxxxxx wrote:

For many applications you want to limit or remove the *diffracted*
light though an aperture, so that the light arriving at the imaging
plane is more closely described by the geometrical optics
approximation.
Intuitively, it would seem if the edge of the opening were rounded
rather than sharp, less diffracted light would be able to bend around
to enter the aperture. This would be particularly true if the radius of
curvature of the edge was large with respect to the wavelength.
Anyone know of references that address diffraction through apertures
with a rounded edge?

Bob Clark

James E. Klein
jameseklein@xxxxxxxxxxxxx

Engineering Calculations
http://www.ecalculations.com
ecalculations@xxxxxxxxxxxxxxxxx
Engineering Calculations is the home of
the KDP-2 Optical Design Program
for Windows.
1-818-507-5706 (Voice and Fax)
1-818-823-4121
.

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