The ESA/JAXA SPICA mission is a candidate for the ESA Cosmic Vision Medium Class M5 opportunity. Since 2019 an Airbus Defence and Space team has been performing a trade-off study (on behalf of ESA) to establish a baseline telescope optical configuration and design, which can meet the mission scientific performance requirements. This paper describes the telescope baseline design selected, with first estimates of the expected optical performance. The optical design wavelength is 20 microns for an operating temperature of 8 K covering a total bandwidth of 12 to 420 microns over a 30 arc minutes field of view, with a total required collecting area of at least 4.0 m². The fundamental mission science driver is to achieve a sky background (astrophysical sources) limited performance. The telescope is designed to illuminate three instruments namely; SMI (JAXA - Japan), SAFARI (SRON - Netherlands) and B-BOP (CEA - France).
During the last few years, the evolution of deposition technologies of optical thin films coatings and associated in-situ monitoring methods enables us today to successfully answer the increasingly request of space systems for Earth observation.
Geostationary satellite COMS-1 (Communication, Ocean, Meteorological Satellite-1) of Astrium has the role of ensuring meteorological observation as well as monitoring of the oceans. It is equipped with a colour imager to observe the marine ecosystem through 8 bands in the visible spectrum with a ground resolution of 500m. For that, this very high technology instrument is constituted with a filters wheel in front of the oceanic colour imager with 8 narrow band filters carried out and qualified by Cilas.
ATLID (ATmospheric LIDar) is one of the four key instruments of EarthCARE (Earth Clouds, Aerosols and Radiations Explorer) satellite. It is a program of and funded by the European Space Agency and under prime contractorship of Airbus Defence and Space. ATLID is dedicated to the understanding of aerosols and clouds contribution to earth climate. It is an atmospheric LIDAR that measures the emitted 354.8nm ultraviolet laser which is backscattered by the atmosphere. The molecules and the particles have different optical signatures and can consequently be distinguished thanks to polarization analyses and spectral filtering of the backscattered signal. The following optical units of ATLID receiver chain directly contribute to this function : after ATLID afocal telescope, the CAS-OA, the Optical Assembly of the Co Alignment Sensor, samples and images the beam on the CAS sensor in order to optimize the alignment of transmitting and receiving telescopes. The beam goes through the BF sub-assemblies, the Blocking Filter which has two filtering functions: (1) spatial with the ERO-BF, which is a Kepler afocal spatial filtering module that defines the instrument field of view and blocks the background and straylight out of the useful field of view; (2) spectral with the ERO-EFO, the Entrance Filtering Optic, which is mainly composed of a very narrow bandpass filter with a high rejection factor. This filter rejects the background from the useful signal and contributes to increase the signal-to-noise ratio. The EFO also allows an on-ground adjustment of the orientation of the linear polarization of the input beam. After filtering and polarization adjustment, the beam is injected in several optical fibers and transported to the instrument detectors. This last transport function is done by the FCA, the Fiber Coupler Assembly. This paper presents the flight models of the previously described units, details the opto-mechanical design, and reviews the main achieved performances with a focus on following main specific characteristics: (1) the spectral filtering capabilities of the EFO: Full Width at Half Maximum (FWHM) <0.70 nm, peak transmission >0.90, mean rejection <10-5 over [320–420] nm; (2) the line of sight stability of the BF: <40 μrad in a very compact design; (3) the high transmission (>0.90) and line of sight stability (<40μrad) of the FCA; (4) the UV laser induced contamination control plan, with end of life contamination level requirements <1mg/m² for molecular and 50 ppm for particulate contamination.