MIRI Instrumentation

The JWST Mid-Infrared Instrument (MIRI) provides 4 observing modes from 5 to 28.5 μm that include optical, spectral, and occulting capabilities.

The major pieces of instrumentation hardware necessary to support these modes include the components listed below:

  • Optics and focal plane—the imager (MIRIM) and medium resolution spectrometer (MRS) are fed from a single pick-off mirror (POM).
  • Filters—there are 10 filters for imaging, 4 filter-diaphragm combinations for coronagraphy, one neutral density filter, one ZnS-Ge double prism for the LRS mode, one opaque position for darks, and one for a lens used during ground tests.
  • Coronagraph masks—one occulter is based on the classic Lyot design and there are 3 occulters that incorporate 4-quadrant phase masks (4QPMs).  
  • Spectroscopic elements—a double prism is used for the low-resolution spectrometer and there are 2 dichroic filter combination wheels for the medium-resolution spectrometer.
  • Detectors are 3 impurity band conduction (Si:As IBC) devices.
  • Integral field units (IFUs)—there are 4 IFUs for the medium resolution spectrometer.




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