Patent attributes
The technology relates to detecting water or fouling on the exterior surface of a sensor cover, for instance due to precipitation or debris (fouling). Such objects on the sensor cover surface may degrade operation of the sensor, which can be problematic for vehicles operating in an autonomous driving mode. According to an aspect of the technology, a waveguide layer is provided on the sensor cover. A laser emits light at a selected wavelength along one side of the waveguide layer. The light waveform propagating along the waveguide layer is affected (distorted) by precipitation and/or fouling on the surface of this layer. A detector receives the distorted waveform. The system determines whether water and/or fouling is present based on the received waveform. This allows the system to determine whether to activate a cleaning module or to factor in the information when processing received sensor data.
