Line-of-sight optical Dome Turbulence Monitor

Abstract

ABSTRACT Optical turbulence in the enclosure of a ground-based telescope can be a major contributor to the total optical turbulence strength and can therefore limit the precision of astronomical observations, in terms of angular resolution, or signal to noise ratio, depending on the instrumentation used. Here we propose a new Dome Turbulence Monitor (DTM) technique. This DTM is based on the well known Scintillation Detection And Ranging (SCIDAR) concept with a few major differences. By designing the instrument specifically for the dome turbulence, we can use a small (<0.2 m telescope), and observe single bright stars (as opposed to the SCIDAR using double stars). This enables a dedicated instrument with enough targets to operate continuously. Operationally, the DTM could be mounted somewhere on the main astronomical telescope and track stars that are visible through the dome aperture. By measuring through the dome aperture we obtain an optical measure of the strength of the turbulence along a similar line of sight as the main telescope itself. We demonstrate the new technique through numerical Monte Carlo modelling and present results from a proof-of-concept demonstration at the European Space Agency Optical Ground Station on Tenerife, Spain.