A Machine Vision System for Automated Headlamp Lens Inspection

Headlamps on vehicles are primarily responsable for illuminating the traffic space during periods of low visibility, such as night or precipitation. In addition, headlamps are also considered as a cosmetic part, playing an important role in the car styling. Because of this, carmakers request a great precision for surface defect detection in all the headlamp components. One of these components is the cover lens (Fig. 1). This part used to be made of glass but polycarbonate lenses have become today’s standard. In comparison to glass, plastic lenses have the advantages of higher resistance to impact, lower weight, small manufacture tolerances and much greater freedom of design thanks to the possibility of undercuts [Wördenweber et al. (2007)]. But for scratch resistance, policarbonate lenses must be coated. Failures during the manufacturing and coating process lead to different kind of defects known as aesthetic defects. Although this kind of defects do not entail any functional disadvantage, may be considered as aesthetically displeasing.