The Imager subsystem of METIS, the Mid-infrared ELT Imager and Spectrograph for the Extremely Large Telescope (ELT) in Chile, provides diffraction-limited imaging capabilities and medium-resolution spectroscopy over the full wavelength range 3 to 13 microns. This Imager has a collimator that feeds two cameras: LM bands and N band. A dichroic splits the bands into two camera optics and to the corresponding detectors. It also incorporates a precise pupil re-imaging optics for each channel, allowing the positioning of high contrast imaging masks for coronographic applications. The collimator and the two cameras are Three-Mirror Anastigmat systems (TMA). All mirrors' surfaces are freeform defined as Zernike surfaces directly polished onto bare aluminium. This optics permits diffraction-limited performance and allows diffraction-limited spectroscopy in the complete wavelength range as well as the required pupil performance. The Imager works at 40 Kelvin to provide detector-limited performance in both bands, while the fore optics of METIS operates at 70 Kelvin. Therefore, a kinematic mounting has been implemented to allow the temperature difference but at the same time keeps the optics aligned to the challenging accuracy required for high contrast imaging. We will present the optics design, the final opto-mechanics and their ongoing manufacturing at Fraunhofer Institute for Applied Optics and Precision Engineering (IOF).
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