Patent ID: 8293057

Claim:
A method of fabricating an apertured polymeric film, said method comprising the steps of: (a) masking a polymeric film with a first mask having one or more first laser transmission zones defined therein; (b) laser-ablating one or more first apertures through an entire thickness of said polymeric film using said first mask; (c) masking said film with a second mask having one or more second laser transmission zones defined therein, each second zone being aligned with a corresponding first aperture, and each second zone having greater perimeter dimensions than said corresponding first aperture; and (d) reaming said one or more first apertures by laser-ablating through an entire thickness of said polymeric film using said second mask, said reamed first apertures defining one or more second apertures in said film, wherein each first aperture has perimeter dimensions about 5 to 30 microns less than predetermined perimeter dimensions of a corresponding second aperture, and wherein said first apertures are lined with carbonaceous deposits and said second apertures are substantially free of said carbonaceous soot deposits.