Integrating sphere measures ultraviolet flux

A 2-m-diameter integrating sphere lined with Spectralon reflectance material will be used as part of the new National Physical Laboratory (NPL, Teddington, England) facility for measuring the total flux of lamps in the UV. The large integrating sphere was used previously by NPL with its original barium sulfate coating to provide calibration in the visible spectrum. The new liner, however, will provide a much higher level of reflectivity in the spectral region below 380 nm, which will allow the laboratory to offer a unique calibration service for spectral flux in the UV. Other measurements, such as diffuse reflectance of physically large samples, will also be possible after slight modifications to the system.

The geodesic Spectralon liner was designed by Labsphere (North Sutton, NH) and is made of more than 180 interlinked triangular tiles of the company`s proprietary thermoplastic bolted to the interior of the sphere. Spectralon provides the highest diffuse optical reflectance of any known material across the entire 250-2500-nm spectral range.