The invention provides an optical system comprising an optical element that is improved in terms of resistance to scratching, weather resistance, etc. An extremely flexible and practical switching region check is achieved in at least one embodiment by the fact that a change in at least one system parameter of the switching system derives at least one first piece of information on the position of the signal emitter. Secondary refrigerant is subsequently at least partially thawed, in a secondary evaporator, by re-absorption thereby of secondary latent heat from material proximal to secondary evaporator. Accordingly, the cross-connect system can supply dual-mode communications. Thus, a call can be established without tactile interaction with the device and, moreover, with minimal computational load on the device.