Measurement of the optical turbulence produced by a drone

Abstract

© The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. At present, new approaches for the use of drones in high-precision optical applications are rising, especially with those known as multirotor. However, the optical turbulence effects generated by multirotor drones are not entirely understood. These optical effects can reduce the performance of the optical instruments that they transport. We present measurements of the wavefront deformation generated by the temperature fluctuations and the airflow of a drone's propulsion system. To do so, we used a single arm of a DJI S800 EVO Hexacopter (professional drone) and measured its operating temperature with a commercial infrared camera. The resulting temperature variation, between a switched-off propulsion system at room temperature and one running at its maximum performance, was 34.2°C. Later, we performed two different interferometric tests: Takeda's method and the phase-shifting technique, using a ZYGO interferometer. These tests show that the total deformation over an incident wavefront to the propeller airflow is lower than 0.074 λ PV and 0.007 λ RMS (HeNe laser, λ = 633 nm). We determine that the optical turbulence produced by a drone propulsion system is negligible.