US Patent 9033237 Decoding DPM indicia with polarized illumination

A method of decoding a Direct Part Marking (DPM) indicia. The method includes: (1) generating a polarized illumination light; (2) illuminating the DPM indicia with the polarized illumination; (3) detecting light scattered from the DPM indicia through a linear polarizer with an imaging sensor while the DPM indicia is illuminated by the polarized illumination to capture an image of the DPM indicia though an imaging lens while preventing at least 80% of onetime scattered light caused by the target object from entering the imaging lens; and (4) processing the image of the DPM indicia to decode the DPM indicia.