SWS INSTRUMENT

3.) Shutter mechanism

SWS has three entrance apertures:

­ four-position shutter:

• selects one of the three apertures,
  and closes off the remaining ones

• or blocks all three (aperture "closed")

­ shutter mechanism:

• two vanes with two rectangular cutouts

• with two stable positions (fixed magnets)

• each with its own mechanism (two coils)

• operating completely independent

­ aperture selection:

• by overlap of cutouts of the two vanes

• the apertures are spatially separated
  => they see different parts of the sky

• spacecraft pointing has to be adjusted
  in a way, that the target is imaged onto
  the appropriate aperture

• the cutouts are larger than the beam
  => they do not determine the FOV

SWS TUTORIAL / SWS INSTRUMENT : ... layout < shutter > dichroics ...