The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS instrument on board the Rosetta spacecraft, a mission of the European Space Agency to comet PWirtanen, includes two cameras for acquiring images of the comet. A set of interference filters deposited upon glass and fused-silica substrates will be added to the cameras for wavelength tuning. For this mission of more than 10years in an interplanetary environment, the requirement of preserving the optical characteristics of the filters is a critical one. We checked the variation in the transmission of some filter substrates after proton irradiation that simulated the solar wind. To produce a situation that is representative of the interplanetary environment, we irradiated proton fluences at three energies: 1.5 1011 protonscm2 at 4 MeV, 1.9 1010 protonscm2 at 8 MeV, and 7.1 109 protonscm2 at 18 MeV. Seven substrates were tested: three Suprasil-1; three colored glasses, namely, OG590, KG3, and RG9; and one quartz. In addition, two interference filters were checked. The results obtained show that Suprasil-1 is rather insensitive to this irradiation, whereas very small reductions in transmission, of the order of a few percent, occur for colored glasses. The transmission of these filters was remeasured 2 years after the irradiation, and showed a general decrease in the transmission reduction.
Effects of proton irradiation on glass filter substrates for the Rosetta mission
NALETTO, GIAMPIERO;
2003
Abstract
The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS instrument on board the Rosetta spacecraft, a mission of the European Space Agency to comet PWirtanen, includes two cameras for acquiring images of the comet. A set of interference filters deposited upon glass and fused-silica substrates will be added to the cameras for wavelength tuning. For this mission of more than 10years in an interplanetary environment, the requirement of preserving the optical characteristics of the filters is a critical one. We checked the variation in the transmission of some filter substrates after proton irradiation that simulated the solar wind. To produce a situation that is representative of the interplanetary environment, we irradiated proton fluences at three energies: 1.5 1011 protonscm2 at 4 MeV, 1.9 1010 protonscm2 at 8 MeV, and 7.1 109 protonscm2 at 18 MeV. Seven substrates were tested: three Suprasil-1; three colored glasses, namely, OG590, KG3, and RG9; and one quartz. In addition, two interference filters were checked. The results obtained show that Suprasil-1 is rather insensitive to this irradiation, whereas very small reductions in transmission, of the order of a few percent, occur for colored glasses. The transmission of these filters was remeasured 2 years after the irradiation, and showed a general decrease in the transmission reduction.
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
