Design of the MWIR channels of EChO

In this paper, we present the design of the MWIR channels of EChO. Two channels cover the 5-11 micron spectral range. The choice of the boundaries of each channel is a trade-off driven by the science goals (spectral features of key molecules) and several parameters such as the common optics design, the dichroic plates design, the optical materials characteristics, the detector cut-off wavelength. We also will emphasize the role of the detectors choice that drives the thermal and mechanical designs and the cooling strategy.