LESIA (Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris-Meudon) has an extensive experience in visible and infrared imaging spectrometry with several instruments onboard planetary space missions (MarsExpress/OMEGA, VenusExpress/VIRTIS, Rosetta/VIRTIS).
The Exoplanet Characterisation Observatory, EChO, is a dedicated space mission to investigate the physics and chemistry of Exoplanet atmospheres. Using the differential spectroscopy by transit method, it provides simultaneously a complete spectrum in a wide wavelength range between 0.4μm and 16μm of the atmosphere of exoplanets. The payload is subdivided into 6 channels. The mid-infrared channel covers the spectral range between 5μm and 11μm. In order to optimize the instrument response and the science objectives, the bandpass is split in two using an internal dichroic. We present the opto-mechanical concept of the MWIR channel and the detector development that have driven the thermal and mechanical designs of the channel. The estimated end-to-end performance is also presented.