Etalon Development for the DKIST Visible Tunable Filter Instrument

Michael Sigwarth, Kiepenheur Institut fuer Sonnenphysik

The Visible Tunable Filter (VTF) instrument is a 2D spectro-polarimeter, based on air spaced Fabry-Perot Etalons with a clear aperture of 250mm. It is currently under construction at the Kiepenheuer-Institut, Freiburg, Germany (KIS). The VTF will be one of the DKIST first light instruments. Currently the first Etalon is being assembled at KIS and mechanical interfaces are being installed at DKIST.

In the talk I will give a brief overview on the science specifications of the VTF and the overall design. The Etalons needed for the VTF are the largest Fabry-Perot Etalons for optical applications in the visible build so far. In the talk I will present the most challenging technical requirements for these devices and how they have been achieved.