The invention concerns a method for preparing at least one fluorinated compound film by vacuum deposit formation, which consists in, simultaneously with the vacuum deposition, also generating and/or introducing in the gas phase, at least a reducing species and elemental, molecular or bound fluorine, thereby producing during its deposit formation the fluorination of the fluorinated compound film. The invention also concerns the resulting thin films and thin film layers. Said films or film layers deposited on a substrate can ensure an optical function, such as mirror, spectral filter or antiglare coating, in the spectral field ranging from ultraviolet to infrared, or act as protective coating on optical components for example for protecting them against intense laser flux or against corrosive atmosphere.