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19 August 1996 Shift-free narrowband filters for the UV-B region
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Monitoring of stratospherical ozone depletion by filter radiometers calls for narrowband filters with outstanding parameters. At filter wavelengths down to 300 nm narrow bandwidth, high peak transmittance together with high out- of-band blocking especially at longer wavelength are demanded. Furthermore, filters have to be completely free of wavelength shift caused by humidity. Conventional interference filters suffer from such shift because of the water sorption of the evaporated layers. By using plasma ion assisted deposition of zirconia and silica layers we succeeded in manufacturing blocked two-cavity filters with full width at half maximum of 1.7 nm and peak transmittance of 17 percent to NIR optical density is at least 6. There was no decrease in wavelength of such filters by changing relative humidity from 100 percent to 0 percent. Corresponding conventional filters shifted 4.5 nm under the same conditions. The filter performance achieved allows use for the development of sensitive and specific instrumentation for environmental, climate, and meteorological research.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hein Uhlig, Uwe B. Schallenberg, and Norbert Kaiser "Shift-free narrowband filters for the UV-B region", Proc. SPIE 2776, Developments in Optical Component Coatings, (19 August 1996);


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