Multi-slit masks for DIS:

• From the top of the filter wheel,
  • filter is held on with two screws with plastic clamps holding the filter
  • filter holder is held on with two screws. Inside the bottom of the filter holder, there are taped two pieces of paper that block the side edges of the filter.
  • slitmask is next. Narrow part of slits is up
  • spacer is next
• The 16 slits come close to the edge, but it seems that you could fit one, perhaps two more on each side.
• Size of mask:
  • 2.9" by 2.14" by 0.0385"
    Rounding of corners starts about 0.15" in from the corners. Note these dimensions have a little bit of "slop" in the filter wheel
  • spacer is 0.041" thick
  • wide part of slit is about 0.05"
  • narrow too hard to measure, about 0.02"?
    Note that 0.33 is scratched on the slit: 0.35mm is 0.0138", and is very close to 2" in the focal plane of the f/10 3.5m
  • slit spacing: 1.47" from first to last slit: 1.47/15=0.098" spacing, very close to 15"