Distances between various locations:

Field lens to pupil lens................................5.25"

inner diameter of snout.................................2.875"

pupil lens to He-3 pot..................................2.74"

inner surface of He-4 lid to pupil lens.................0.70" (approx.)

pupil lens to first bend in optical path................1.25"

first bend to bend at grid 1............................1.50"

first bend to bend at grid 2............................3.00"

He-3 surface to He-4 surface............................5.00"

inner surface of He-4 lid to He-3 pot...................3.425" +/- 0.015"

inner surface of He-4 lid to plane above which no
plumbing extends........................................4.69" (approx.)

angle by which optic axis deviates from dewr radius.....22°

amount to translate grid 1 to avoid vignetting..........2 mm

amount to translate grid 2 to avoid vignetting..........1 mm

Height of optics shelves relative to He-4 cold surface

Upper optics shelf.......................7.930" - 8.230"
Lower optics shelf......................4.300" - 4.600"

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Contact tom@clark.phys.nwu.edu. Last updated July 1, 1998