1. The Mid-Infrared Instrument (MIRI) Medium Resolution Spectrometer for JWST Martyn Wells MIRI EC & UKATC

2. Carbon Fibre Hexapod (Denmark) Spectrometer Main Optics Netherlands Imager (France) Input Optics and Calibration Unit (Belgium) Deck (Leicester) Spectrometer Focal Plane Module (USA) Spectrometer Pre Optics UKATC

3. Summary description

4. Spectrometer block diagram SPOSMO

5. Spectrometer fov

6. Dichroic passbands Exposure A Exposure B Exposure C

7. Spectrometer – ranges, R, sampling and fov

9. Ray-trace diagram of the Channel 1 IFU

10. Diagram of the output slit

11. Integral Field Unit Optical Layout Spectrometer Pre-Optics

13. Here are the flattened envelopes of the sliced and stacked sky images, heading off to the spectrometer collimator mirrors in the Spectrometer Main Optics (SMO) The position of the Channel 2 collimator mirror

14. Here, the beam from the Channel 2 collimator is shown, heading back to one of Channel 2’s three diffraction gratings. The position of a Channel 2 grating.

15. The light is dispersed by the grating. Dispersion direction

16. ...and heads back to a fold mirror.

17. ...which sends it to the final, camera mirror, which is a common optical element for Channels 1 and 2 (as is the fold mirror)

18. The camera mirror forms the final image...

19. ...on the Focal Plane Module (FPM), shown here as the green cylinder.

20. Here comes the beam from the Channel 1 IFU, collimated and sent to one of Channel 1’s 3 gratings...

21. ...where it is dispersed...

22. ...and sent via this fold mirror to share the last two mirrors on its way to the FPM with the spectrum from Channel 2.

23. Channel 2a spectra Constant wavelength positions

24. Some manufactured components