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Size of this preview: 600 × 600 pixelsFull resolution (1,000 × 1,000 pixels, file size: 260 KB, MIME type: image/png)
[edit] Description
| 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.
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| Source |
Home brewed picture
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| Date |
created 19. Aug. 2005
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| Author |
Georg Wiora (Dr. Schorsch)
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Permission
(Reusing this image) |
CC-BY-SA 2.5, 2.0, 1.0 and GFDL by the Author
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[edit] Licensing
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I, the copyright holder of this work, have published or hereby publish it under the following license:
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[edit] How To
The 8-bit intensity values I of this image were computed by the following formula:

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/Time | Dimensions | User | Comment |
| current | 05:29, 17 May 2008 | 1,000×1,000 (260 KB) | Falcorian | |
| 14:11, 19 August 2005 | 1,000×1,000 (296 KB) | Xorx | |
File links
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