LOLAS: an optical turbulence profiler in the atmospheric boundary layer with extreme altitude-resolution

TL;DR

LOLAS is a novel optical turbulence profiler that uses a small 40-cm telescope and a double-star method to achieve unprecedented 12-meter altitude-resolution in boundary layer turbulence measurements.

Contribution

It introduces a compact, independent instrument based on the Generalized Scidar concept with high altitude-resolution capabilities and novel algorithms for atmospheric turbulence profiling.

Findings

Achieved 12-meter altitude-resolution turbulence profiles.

Demonstrated system capabilities at Mauna Kea Observatory.

Instrument built for ground layer turbulence monitoring for Gemini Observatory.

Abstract

We report the development and first results of an instrument called Low Layer Scidar (LOLAS) which is aimed at the measurement of optical-turbulence profiles in the atmospheric boundary layer with high altitude-resolution. The method is based on the Generalized Scidar (GS) concept, but unlike the GS instruments which need a 1- m or larger telescope, LOLAS is implemented on a dedicated 40-cm telescope, making it an independent instrument. The system is designed for widely separated double-star targets, which enables the high altitude-resolution. Using a 20000-separation double- star, we have obtained turbulence profiles with unprecedented 12-m resolution. The system incorporates necessary novel algorithms for autoguiding, autofocus and image stabilisation. The results presented here were obtained at Mauna Kea Observatory. They show LOLAS capabilities but cannot be considered as representative of the site. A forthcoming paper will be devoted to the site characterisation. The instrument was built as part of the Ground Layer Turbulence Monitoring Campaign on Mauna Kea for Gemini Observatory.