Infrared optical coatings for the EarthCARE Multispectral Imager
14 October 2014
Our latest paper entitled 'Infrared optical coatings for the EarthCARE Multispectral Imager' has just been published in the Optical Society of America, Applied Optics journal. The paper is open access so anyone can download a copy.
Infrared optical coatings for the EarthCARE Multispectral Imager
G J Hawkins, D Woods, R E Sherwood, K Djotni
Applied Optics, Vol. 53, Issue 27, pp. 6983-6992 (2014)
Abstract
The Earth Cloud, Aerosol and Radiation Explorer mission (EarthCARE) Multispectral Imager (MSI) is a radiometric instrument designed to provide the imaging of the atmospheric cloud cover and the cloud top surface temperature from a sun-synchronous low Earth orbit. The MSI forms part of a suite of four instruments destined to support the European Space Agency Living Planet mission on-board the EarthCARE satellite payload to be launched in 2016, whose synergy will be used to construct three-dimensional scenes, textures and temperatures of atmospheric clouds and aerosols. The MSI instrument contains seven channels: four solar channels to measure visible and short-wave infrared wavelengths, and three channels to measure infrared thermal emission. In this paper, we describe the optical layout of the infrared instrument channels, thin-film multilayer designs, the coating deposition method and the spectral system throughput for the bandpass interference filters, dichroic beam splitters, lenses and mirror coatings to discriminate wavelengths at 8.8, 10.8, & 12.0 µm. The rationale for the selection of thin-film materials, spectral measurement technique, and environmental testing performance are also presented.