AGING OF MATERIALS UNDER INTENSE ULTRAVIOLET-RADIATION

Sources of intense ultraviolet (UV) radiation are increasingly used in industry, for sterilization of air and water, photolithography, print ing, etc. However, the damaging nature of intense UV makes the accurat e measurement of the spectral characteristics of intense UV sources ex tremely difficult. For this reason, the National Physical Laboratory i s currently developing a new spectroradiometer, designed specifically for the characterization of sources of this type. An important early s tage in the design of this facility was an investigation into the agei ng effect produced by intense UV radiation on the materials being cons idered for use in the spectroradiometer optics. This involved the meas urement of the spectral reflectance of mirror coatings and diffusely r eflecting materials before and after irradiation. Xenon and mercury di scharge lamps were used to provide UV irradiance levels at about the 5 0 mW . m(-2). nm(-1) level and above, between 200 nm and 400 nm. This paper presents the results obtained from this investigation.