# Measurement of the Optical Turbulence Produced by a Multirotor Unmanned Aerial Vehicle

## TL;DR

This study measures the optical turbulence caused by a multirotor drone's airflow and temperature fluctuations, finding it to be negligible for high-precision optical applications.

## Contribution

It provides the first quantitative assessment of optical turbulence effects from drone propulsion systems using interferometric techniques.

## Key findings

- Optical turbulence deformation is below 0.074 λ PV and 0.007 λ RMS.
- Temperature variation of 34.2°C observed between off and maximum performance.
- Optical turbulence from drone propulsion is negligible for optical instruments.

## Abstract

At present, new approaches for the use of Multirotor Unmanned Aerial Vehicle or multirotor drones in high precision optical applications are rising. 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. This paper presents 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{\deg} 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 \lambda PV and 0.007 \lambda RMS (HeNe laser, \lambda=633nm). We conclude that the optical turbulence produced by a drone propulsion system is negligible.