Measurement concept to reduce environmental impact in direct time-of-flight LiDAR sensors

For some applications, a reliable detection of the distance of objects is necessary, even under strong environmental conditions. Commonly this includes sunlight, but fog, rain and snow cause interferences as well. For fast and reliable threedimensional monitoring of the environment, LiDAR is a key sensor technology. A light source, often in the near-infrared, emits a short light pulse and the time-of-flight of the photons reflected by an object is measured. This allows to calculate the distance by using the speed of light. In order to be able to ensure reliable detection despite possible interferences, we have set up a new measurement concept based on the existing time-gating. Thus, an area is covered by step-wise shifting of the measuring window. By accumulating different delays, the true distance to the object can be determined. An advantage of the method is that no information about the approximate position of the object has to be known in advance. In this paper we present measurement results with this method, which were taken in different environmental conditions. The method can be implemented in addition to already existing concepts and can therefore supplement them.