Jean-Hervé Lecat

Synthetic aperture co-phasing and co-alignment using an external reference source

A breadboard set-up has demonstrated a concept of cophasing and co-alignment based on an external reference source for synthetic aperture telescopes applications. These types of systems can be extremely valuable in order to perform coarse re-alignment of synthetic aperture telescope, following thermo-elastic deformation and deployment effects in space flight environments.

Performance of solmacs, a high PV solar concentrator with efficient optics

A new solar panel with high concentration photovoltaic technology (x700) has been designed, prototyped and tested in the SOLMACS project. The quality of concentrating optics is a key factor for high module efficiency. Therefore new dedicated PMMA Fresnel lenses were studied and produced by injection molding. Lens design, material and production process were optimized to achieve a high optical yield of 86%. Thorough lens performance assessment in optical laboratory was completed with lifetime UV aging tests. Another important aspect is the thermal control of the hot spot created under the solar cell that receives the concentrated flux of 700 Suns. A dedicated heat spreader was developed to achieve passive thermal control with minimum mass and cost. This was supported by thermal models and tests at both cell and module level. 35% triple junction cells were implemented in the module. Micro-assembly technologies were used for the cell packaging and electrical connections. In support to the research, a continu...

SWAP: an EUV imager for solar monitoring on board of PROBA2

PROBA2 is an ESA technology demonstration mission to be launched in early 2007. The two primary scientific instruments on board of PROBA2 are SWAP (Sun Watcher using Active Pixel System detector and Image Processing) and the LYRA VUV radiometer. SWAP provides a full disk solar imaging capability with a bandpass filter centred at 17.5 nm (FeIX-XI) and a fast cadence of ≈1 min. The telescope is based on an off-axis Ritchey Chretien design while an extreme ultraviolet (EUV) enhanced APS CMOS will be used as a detector. As the prime goal of the SWAP is solar monitoring and advance warning of Coronal Mass Ejections (CME), on-board intellige nce will be implemented. Image recognition software using experimental algorithms will be used to detect CMEs during the first phase of eruption so the event can be tracked by the spacecraft without huma n intervention. LYRA will monitor solar irradiance in four different VUV passbands with a cadence of up to 100 Hz. The four channels were chosen for their relevance to solar physics, aeronomy and space weather: 115-125 nm (Lyman-α), 200-220 nm Herzberg continuum, the 17-70 nm Aluminium filter channel (that includes the HeII line at 30.4 nm) and the 1-20 nm Zirconium filter channel. On-board calibration sources will monitor the stability of the detectors and the filters throughout the duration of the mission.

Development of an infrared collimator as optical ground support equipment for IASI instrument

The Infrared Atmospheric Sounding Interferometer (IASI), an instrument to be carried on METOP satellites, has been developed by Alcatel Space, for final use by CNES and EUMETSAT. The objective is an improvement of vertical resolution and accuracy of temperature and humidity atmospheric profiles measurement. This development created the need of an infrared collimator whose mission is to characterise Pixel Angular Response and to localise optical axis of the flight hardware. For this purpose, a collimator covering the spectral range 645 - 2760 cm-1 has been designed, manufactured in collaboration with AMOS company and delivered to Alcatel Space. Infrared source uses a blackbody working from 310 to 1200 K followed by spectral filtering. Motorization allows angular orientation on two axes around the IASI instrument entrance pupil with a 10 μrad accuracy. The present contribution will provide the critical points, which have been identified and solved during manufacturing and testing inside CSL vacuum facilities.