File:Zonenplatte Cosinus.png

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Full resolution ‎(1,000 × 1,000 pixels, file size: 260 KB, MIME type: image/png)

[edit] Summary

Description
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 created 19. Aug. 2005
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

[edit] Licensing

w:en:Creative Commons
attribution share alike		 This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic, 2.0 Generic and 1.0 Generic license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).
  • share alike – If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.
I, the copyright holder of this work, hereby publish it under the following licenses:
GNU head 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.

w:en:Creative Commons
attribution share alike		 This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).
  • share alike – If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.
This licensing tag was added to this file as part of the GFDL licensing update.

You may select the license of your choice.

[edit] How To

The 8-bit intensity values I of this image were computed by the following formula:

I(r) = COS(\frac{r^2}{5120})\cdot 127 + 128

where r 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

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current05:29, 17 May 2008Thumbnail for version as of 05:29, 17 May 20081,000 × 1,000 (260 KB)Falcorianpngout compression.
14:11, 19 August 2005Thumbnail for version as of 14:11, 19 August 20051,000 × 1,000 (296 KB)Xorx{{Information| |Description = Frenel's zone plate with sinusoidal transparency. |Source = Home brewed picture |Date = created 19. Aug. 2005 |Author = Georg Wiora ~~~ |Permission = Put under the GFDL by the Author. |other_versions = - }} {{GFDL-self}}
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