A method of forming a conformable filter for a vehicle window, comprising the steps of: —selecting at least a first wavelength corresponding to a predetermined laser threat; —providing a conformable photosensitive film and exposing said film to radiation from a focused laser source of said first wavelength to create a first filter region therein configured to substantially block incident radiation thereon substantially only of said first wavelength; —determining if an essential lighting source outside or inside the vehicle includes said first wavelength and, if so, —selecting a bandwidth corresponding to a first predetermined wavelength band including said first wavelength and exposing said polymeric film to radiation from one or more further laser sources of respective different wavelengths within said first predetermined wavelength band to create a notch filter region therein, including said first filter region, said notch filter region being configured to substantially block incident radiation thereon at wavelengths within said first predetermined wavelength band whilst substantially allowing visible wavelengths outside of said first predetermined wavelength band to be transmitted therethrough, and wherein said bandwidth is selected to optimise visibility through said filter of said essential lighting source.
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