Wavelength selective photocatalytic dielectric elements on polytetrafluoroethylene (PTFE) refractors having indices of refraction greater than 2.0

摘要

This invention relates to a photocatalytic dielectric element placed upon polytetrafluoroethylene (PTFE) refractors and lamp covers to provide a self-cleaning surface for use on roadway lighting fixtures. The photocatalytic dielectric element is comprised of a series of hard durable thin dielectric film layers that can be tailored to selectively reflect UV with a plurality of dielectric layers having indices of refraction greater than 2.0. The photocatalytic dielectric element is otherwise transmissive to light at all other wavelengths. In addition, the photocatalytic dielectric element can concentrate photons generating from the light fixture, or from direct sunlight within a narrow range of wavelengths on the outer surface of the polytetrafluoroethylene refractor or lamp cover. In turn this promotes photocatalytic reactions that decompose bacteria and other organic contaminates that contact the polytetrafluoroethylene refractor or lamp cover where the photocatalytic dielectric element is placed upon, thus, making the light fixture self cleaning. The photocatalytic dielectric element can be placed on what is termed as, “difficult to adhere to substrate materials”, such as the polytetrafluoroethylene, while maintaining good adhesion without delamination, in addition to most any other substrate material. The photocatalytic dielectric element preferably has been deposited on the surface of the polytetrafluoroethylene refractor by dual alternating low-pressure environment deposition techniques.