A device and method for protecting an optical sensor of a vehicle are disclosed, wherein the sensor is protected from environmental pollutants which may adhere to an optical surface of the sensor if the sensor is exposed to them, and wherein the environmental pollutants are kept away from the sensor by an ultrasonic cleaning of the sensor surface using an ultrasonic field. The ultrasonic field of the ultrasonic cleaning is emitted by a protection device into the air to provide a protection zone around the optical surface of the sensor such that a contact of the optical surface with the environmental pollutants is avoided, wherein the environmental pollutants are moved and/or destroyed in the air away from the sensor if they enter the protection zone), and wherein the protection zone provides a contactless cleaning of the sensor.