FRESNEL Quick Guide |
Spatial frequency filtering is an operation by which one
removes (or passes preferentially) certain desired spatial frequencies by
placing filters in the Fourier transform plane. The principal kinds of filters
that one encounters in the frequency filtering techniques are:
Low-Pass Filters. These filters pass only low
frequencies, i.e. those frequency components lying near the axis. A typical
example of their application is suppression of the high frequency beam spatial
modulation using Spatial Filters in High Power Laser Systems.
High-Pass Filters. These filters allow the high
frequencies pass through while the low frequencies are stopped. Such filters are
used in edge enhancement. An example of the scheme and the result of modeling
are given below (results can be reproduced using contour.scm and contour.pls.
The scheme can be run with FRESNEL Demo using the discretization 128x128 sampling points that will provide the precision slightly worse than 10^{-3}. The discretization 512x512 gives the precision close to 10^{-5}.
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