||Mimir after second
cold test. No broken bones...
Slit belt unit
outer box. This unit was to hold a long steel belt onto which specific
"scenes" were to be photo- or laser-etched. The scenes
would be the different spectroscopic slits and the picket fence
needed for Wollaston prism polarimetry. The belt wrapped up on cogged
rollers to the left and right and a stepper motor drove the belt
back and forth to select the proper scene.
The square opening
at top is about 3.6x3.6 inches and is the physical size of the 10x10
arcmin field of view at the focal plane of the telescope, located
within the Mimir cold volume.
from slit belt unit to reveal the cogged drive rollers (top) and the
belt take-up rollers (underneath). Round opening at bottom fits over
collimator unit, with the first two collimator lenses located within
the volume of this slit belt unit.
Filter box with
four filter wheels installed in filter bay and THK screw-drive rail
system (black) at bottom of camera bay.
half-wave-plate drive stepper motor is located at lower left
showing the four filter wheels, grouped as two wheels bracketing each
of two internal bulkheads, used to control stray light.
one filter cell blank located in a filter cell slot in the third wheel
Side view of
filter box showing four filter wheels, their nested common hub,
and the four drive gears used to rotate each wheel (seen at left,
between leftmost bulkhead of filter box and the first filter wheel).
on side of filter box into filter bay are to hold the sensors that
register the fall of the detent arm with each filter position to
indicate a wheel has a valid filter positioned in the optical beam.
||Top view inside
filter bay. The four wheel gears are at center left. Below them are
a HWP cell with outer gear meshed to the HWP drive gear.
||Front view showing
HWP drive stepper motor (lower right), drive shaft, and HWP drive
gear meshed with geared HWP cell (center of optical beam path).
HWP drive system in more detail. Bearing races can be seen at the
vertical bulkhead holding the motor shaft and in the flat bulkhead
below the optical axis, holding the right angle gear drive and the
final gear engaged with the geared HWP cell in the first filter wheel.
of geared HWP cell and drive gear. The HWP cell is held in place by
two fixed shoulder bearing races (at approximately 1-o'clock and 8-o'clock)
and one shoulder bearing race on a flex pivoted arm (bearing race
at 4-o'clock, flex pivot at 2-o'clock). The pivot arm allows the cell
to be removed. The bearing races allow the cell to rotate. The races
have a cylindrical shape, with flat sides, that engages a rectangular
groove in the cell, locating the cell and controlling tilt or tip