Editing Nipkow disk (section)

== Operation ==
The device is a mechanically spinning disk of any suitable material (metal, plastic, cardboard, etc.), with a series of equally-distanced circular holes of equal [[diameter]] drilled in it. The holes may also be square for greater precision. These holes are positioned to form a single-turn [[spiral]] starting from an external radial point of the disk and proceeding to the center of the disk. When the disk rotates, the holes trace circular ring patterns, with inner and outer [[diameter]] depending on each hole's position on the disk and thickness equal to each hole's diameter. The patterns may or may not partially overlap, depending on the exact construction of the disk. A lens projects an image of the scene in front of it directly onto the disk.<ref>{{cite web |url=http://users.swing.be/philippe.jadin/nipkowdisk.htm |title=The Nipkow disk |last=Jadin |first=Philippe |website=users.swing.be |access-date=2 March 2010 |url-status=dead |archive-url=https://web.archive.org/web/20120415023831/http://users.swing.be/philippe.jadin/nipkowdisk.htm |archive-date=15 April 2012 }}</ref> Each hole in the spiral takes a "slice" through the image which is picked up as a temporal pattern of light and dark by a sensor. If the sensor is made to control a light behind a second Nipkow disk rotating synchronously at the same speed and in the same direction, the image will be reproduced line-by-line. The size of the reproduced image is again determined by the size of the disc; a larger disc produces a larger image.

When spinning the disk while observing an object "through" the disk, preferably through a relatively small [[circular sector]] of the disk (the [[viewport]]), for example, an angular quarter or eighth of the disk, the object seems "scanned" line by line, first by length or height or even diagonally, depending on the exact sector chosen for observation. By spinning the disk rapidly enough, the object seems complete and capturing of [[motion (physics)|motion]] becomes possible. This can be intuitively understood by covering all of the disk but a small rectangular area with black cardboard (which stays fixed), spinning the disk and observing an object through the small area.