March 2005 Mimir Servicing


Completion List


  1. Inspected camera and detector bays– found no aluminum chips or dust. Concluded previous interference problem has been solved.
  2. Fabricated and installed new pupil mask, based on pupil images from December 2004 engineering run.
  3. Moved PK50-1 filter from FW3 to FW2 to support J-band spectroscopy with LM grism with long wavelength blocking
  4. Added second Ks filter (Ks-2) in FW2 as alternate for Ks-1, which shows image features that do not flat-field out.
  5. Removed “beefeater” MLI between floating thermal shields between cold and warm bulkheads. This MLI was believed to be a cause of the slower vacuum pumpdown in November 2004. The floating SS shields were left in place.
  6. Removed 200 W and 75 W heaters and mounting blocks from cold bulkhead.
  7. Realigned all 3 grisms to reduce spectral tilt in the images. Rotated JHK by 1 deg, LM by 1.4 deg, and SED by 2.4 deg.
  8. Ran full 25 cycle He purge of cold head
  9. Replaced He compressor adsorber with “old” one that had been removed prematurely several years ago in BU lab. Compressor hour clock is 08957.1.
  10. Added second flat copper strap from cold head second stage heater block to filter box. This to increase the cooling of the optics/filter box by the 2nd stage.
  11. Removed one of three 1/8” dia copper rods from sapphire thermal feed through block to detector thermal feed through block.
  12. Removed POL wheel encoders with units bits set to one to prevent multiple “home” positions due to mis-encoding of higher order bits. Now, there is only one “home” position reporting (it holds the dark).
  13. Redesigned thermal control and thermal monitoring systems to support new Loop A inputs (primary 2nd stage, secondary 2nd stage, cold bulkhead).
  14. Designed, fabricated new switch plate for back of electronics box to switch Loop A inputs/control lines for the LS331 among the three circuits.
  15. Modified 2nd stage/getter heater block to host a second cartridge-type resistive heater (“R2”) and another thermal sensor (“TA2”).
  16. Installed new cold bulkhead resistive heaters (“R3”) and thermal sensor (“TA3”), taken from decker car.
  17. Removed copper thermal straps from slit and decker cars.
  18. Inspected decker/slit car operations. The cars and their sensors (limits and detents) seem to work fine, but the software does not.