Flight Model of the grating unit. A torquer motor is used to actuate the grating angle which is measured with sub-arcsecond precision by an Inductosyn angular resolver.

Qualification Model of one of the two filter wheels. The motor is the same design as the grating torquer.

Qualification Model of the focal plane chopper. The chopper is used for sky modulation and also to deflect the detector field of view toward 2 internal calibration sources.