The planarizing layer can be substantially smooth and substantially defect free. The term “average surface roughness” Rais defined as the integral of the absolute value of the roughness profile measured over an evaluation length. The term “peak surface roughness” Rpis the height of the highest...
profile. Consequently, the dust that accumulated on the lens surface, either during the lens molding step, or during the service life of the headlamp, was not conspicuously visible. But with the automotive industry moving towards lenses with a smoother profile, the accumulated dust becomes more ...