A 3d-camera device including a dirt detection unit

A 3D-camera device comprising,

• a light guide,
• a Time-of Flight sensor,
• wherein the light guide has a first end for receiving incident light and a second end for emitting received light directed towards the Time-of Flight sensor wherein the first end comprises a light transparent cover having a first portion comprising an outer surface facing the external surroundings of the 3D-camera device,
• a dirt detection unit for detecting dirt on the outer surface of the transparent cover:
• the dirt detection unit including a light source arranged to provide emitted light into the transparent cover, wherein the emitted light is directed in a predetermined angle such that at least a portion of the emitted light is reflected out through a second portion of the transparent cover by dirt present on the outer surface of the transparent cover, and, wherein;
• the Time-of-Flight sensor is arranged to receive the portion of emitted light reflected by dirt on the outer surface of the transparent cover and to output a signal having a magnitude relative the amount of the received portion of emitted reflected light, and;
• a control unit connected to the Time-of-Flight sensor configured to determine the presence of the dirt on the outer surface of the transparent cover from the magnitude of the signal from the Time-of-Flight sensor.