Editing Dutch Open Telescope (section)

== Open structure ==
[[Image:WHT DOT LaPalma.jpg|thumb|right|[[William Herschel Telescope]] and the DOT]]

The DOT is an open telescope, which means that the structure is physically open, and the wind can blow through. Because the wind blows along the mirror the air has a more or less constant temperature, and this prevents [[astronomical seeing|seeing]]. Conventional telescope designs have the problem that hot air from the ground (which is hotter due to solar heating) is blown up along the tower, and this causes air with different temperatures to blow along the telescope, which degrades the image.
A drawback of this open structure is that the skeleton has to be very rigid (do not confuse with strong), to prevent the structure from moving in the wind. Normally a solid tower takes care of this (as is done with the [[Swedish Solar Telescope|Swedish 1-m Solar Telescope]] (SST), for example), or the telescope is placed inside a dome. The DOT does not have this and thus has to be very rigid. The optical part of the telescope is mounted 2 meters in front of the main mirror, and to prevent blurred images, the cameras are mounted very rigidly and can move with a precision of micrometres.

The telescope mirror can be upgraded in size to 3/4 of a meter with small modification, and even larger with additional adaptions.<ref name=":0" />