The Dutch Open Telescope (DOT; http://dot.astro.uu.nl) on La Palma is a revolutionary open solar telescope, on an excellent site, on top of a transparent steel tower, and uses natural air flow to minimize local seeing. The aim is long-duration high-resolution imaging with a multi-wavelength camera system. In order to achieve this, the DOT is equipped with a diffraction limited imaging system and uses the speckle reconstruction technique for removing the remaining atmospheric turbulence. The DOT

more »

... optical system is simple and consists currently of a 0.45m/F4.44 parabolic mirror and a 10x enlargement lens system. We present our plans to increase the aperture of the DOT from 0.45m to 1.4m. The mirror support and telescope top shall be redesigned, but telescope, tower, multi-wavelength camera system and speckle system remain intact. The new optical design permits user selectable choice between angular resolution and field size, as well as transversal pupil shift introducing the possibility to use obstruction free apertures up to 65cm. The design will include a low order AO system, which improves the speckle S/N substantially during moderate seeing conditions.