Filter

Abstract

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.

What is claimed is: 
     
         1 . 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.   
     
     
         2 . The method according to  claim 1 , wherein said film is formed of a photosensitive polymer material. 
     
     
         3 . The method according to  claim 1 , wherein said film has a visible light transmission of at least 85%, and/or a thickness of 1 to 100 micrometers. 
     
     
         4 . The method according to  claim 1 , further comprising the steps of selecting an additional predetermined wavelength band corresponding to visible light emitted by a light source internal to the vehicle, in use, and exposing said film to radiation from one or more focused laser sources of respective wavelength(s) within said additional predetermined wavelength band to create a respective notch filter region therein configured to substantially prevent said light from said internal light source from being seen through the filter from outside of the vehicle. 
     
     
         5 . A conformable filter formed by:
 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.   
     
     
         6 . The filter according to  claim 5 , wherein the first predetermined wavelength band covers or is centred on 532 nm. 
     
     
         7 . The filter according to  claim 5 , wherein the filter is additionally for preventing transmission of radiation in a second predetermined wavelength band, the second predetermined wavelength band covering the wavelength of a second predetermined laser threat and, optionally, wherein the second predetermined wavelength band covers or is centred on 445 nm. 
     
     
         8 . The filter according to  claim 7 , wherein the filter is for additionally preventing radiation in a third predetermined visible radiation band, the third predetermined wavelength band covering the wavelength of a third predetermined laser threat and, optionally, wherein the third predetermined visible wavelength band covers or is centred on 650 nm. 
     
     
         9 . The filter according to  claim 5 , wherein the filter is for preventing radiation from two or more predetermined wavelength bands, including at least one wavelength band corresponding to a predetermined laser threat and at least one wavelength band corresponding to an internal light source of the vehicle. 
     
     
         10 . The filter according to  claim 7 , wherein the filter is comprised by a single layer of material adapted or configured for preventing the transmission of the predetermined visible wavelength bands. 
     
     
         11 . The filter according to  claim 7  wherein the bandwidth of at least one of the predetermined wavelength bands is between 5 nm and 10 nm. 
     
     
         12 . The filter according to  claim 5 , wherein the filter has an optical density of at least 2 at the first and/or each predetermined wavelength band. 
     
     
         13 . The filter according to  claim 5 , wherein the filter is provided as a conformal film for coupling to a window. 
     
     
         14 . The multi-layered window comprising a filter according to  claim 5 , wherein the filter is interposed between layers of the window. 
     
     
         15 . The window for a vehicle, the window comprising a filter according to  claim 5 .