A small, low-cost, turbulence profiling instrument for free-space optical communication

Characterisation and mitigation of atmospheric turbulence is critical for free space optical communication that relies on adaptive optics such as high bit rate coherent modulation or quantum key distribution. Turbulence profiling, i.e. measuring turbulence at different altitudes, provides more detail than typical seeing monitors and supports sophisticated AO and the possibility to forecast conditions. We present the implementation of a Ring-Image Next Generation Scintillation Sensor (RINGSS) instrument that profiles turbulence with a novel approach of defocused ring images introduced by A. Tokovinin (2021)(1). RINGSS is exceptionally low-cost, small, and fully automated, requiring significantly simpler equipment than previous turbulence profilers. We have demonstrated preliminary results that demonstrate the capability of this instrument for measurements of seeing and a low resolution turbulence profile. Future work is outlined that includes cross-calibration with a Stereo-SCIDAR instrument recently commissioned on the ANU 2.3m telescope at Siding Spring Observatory and plans for deployment at prospective optical ground station sites for an Australia-New Zealand optical network.