According to an example aspect of the present invention, there is provided a system for protecting an optical system, the system comprising a hollow first part having at least one first opening, a hollow second part arranged at least partially within the first part, and a coupling section configured to be coupled to the optical system, wherein the system is configured to guide at least a part of an incoming air flow from the at least one first opening along a flow channel between an inner surface of the first part and an outer surface of the second part.