Zonenplatte_Cosinus.png
Size of this preview:
600 × 600 pixels
.
Other resolutions:
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|
480 × 480 pixels
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1,000 × 1,000 pixels
.
Summary
Description Zonenplatte Cosinus.png |
Deutsch:
Frenelsche Zonenplatte mit Sinusförmiger Transparenzfunktion. Programmcode zur Berechnung
siehe unten
.
English:
Frenel's zone plate with sinusoidal transparency. For calculation code
see below
.
|
Date | |
Source | Home brewed picture |
Author | Georg Wiora ( Dr. Schorsch ) |
Permission
( Reusing this file ) |
CC-BY-SA 2.5, 2.0, 1.0 and GFDL by the Author |
Licensing
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Attribution-Share Alike
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2.0 Generic
and
1.0 Generic
license.
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You are free:
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I, the copyright holder of this work, hereby publish it under the following licenses:
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License , Version 1.2 or any later version published by the Free Software Foundation ; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License . http://www.gnu.org/copyleft/fdl.html GFDL GNU Free Documentation License true true |
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This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. | |
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How To
The 8-bit intensity values of this image were computed by the following formula:
where is the distance to the image center in pixels.
The image has been computed with IDL (Interactive Data Language from www.rsinc.com ). The source code is provided here. Copy it into a file named "Zoneplatecosinus.pro" and execute it with IDL.
PRO ZONEPLATECOSINUS ; Pixel size of the image siz=1000 ; Coordinate array xc = LINDGEN(siz,siz) yc = xc / siz xc = TEMPORARY(xc) MOD siz ; Distances to center of array d = SQRT((FLOAT(xc)-siz/2.)^2+(FLOAT(yc)-siz/2.)^2) ; The image of the zone-plate zone = COS(d^2/5120) WINDOW,XSIZE=siz,YSIZE=siz ; Display it TVSCL,zone ; Save as PNG write_png,'zonenplatte2.png',BYTSCL(zone) END