Long-Term Investigations of Weather Influence on Direct Time-of-Flight Lidar at 905nm

This paper reports on the investigation of weather influence on a one channel direct time-of-flight (dToF) Lidar operating at 905nm. The weather-dependent performance degradation is continuously monitored throughout one year at the Bosch Research campus in Renningen close to Stuttgart, Germany. The collected data is analyzed in terms of extinction (i.e. range of vision) and a long-term measurement data base is created. We derive the atmospheric extinction by signal reflection from a reference target as well as direct line of sight measurements with transmitter and receiver being separated by a distance of approximately 100m. Using these findings as a baseline, we furthermore show, that the extinction can be estimated by analyzing the direct backscattering occurring at very close ranges in front of the sensor. This method works independently of the cause for the signal degradation (i.e. rain, hail, snow, fog). For fog scenarios, we fit the backscattering signature with established models known from literature and find a good agreement. Overall, the extinction estimation method based on backscattering shows itself very promising and could be a candidate for implementation in a Lidar sensor system for e.g. automated driving scenarios.