HiCIAO:FocusStageIdeas:072605

1
HiCIAOFocus-Stage-Ideas07-26-05
2
Ball Screw Drive
Linear Ball Slide
For HiCIAO, well bring the drive straight out
through the side of the Cryostat where we have
located the CCC we do not need a right angle
drive as pictured here. An added element for
HiCIAO is the thermal isolation shear webs or
trusses. (all shown in later slides)
3
The Instrument in which this Detector Focus
Mechanism is used is called FLAMINGOS. We have
used Ball Slides in Cshell and CoCo.
Unfortunately I dont have any photographs of
them, so I substituted with these pictures.
4
GNIRS Detector Mechanism
Another exampleHere is a description for the
Detector Mechanism used in GNIRS Mounting the
detector on a BERG ultra precision linear ball
slide controls the focus motion. The slide, part
number BERG LPSK-50A, is rated for a 300-pound
load. The detector focus is driven using a split
screw and nut like that for the slit slide, with
an additional spur gear between the screw and the
motor. The nut, Vespel-SP3, is fastened to the
stage and the screw, 6061-T6 Aluminum, is
anchored to a fixed point using ball thrust
bearings. The spur gear reduction is 4/1. The
gear is 48 pitch, 100 tooth, 0.125 inch wide,
2024-T4 Aluminum, parts number BERG P48A26-100.
The pinion is made from 303 Stainless Steel, 25
tooth, part number BERG P48S21-25. For motor
clearance the gear may be 3/1 bevel type in place
of the above. The repeatability values given in
Table 1 are for this lower precision of motion.
For HiCIAO 1) The repeatability is something we
need to decide on for HiCIAO. For GNIRS it is 50
micron and the range is /- 2.5 mm 2) Another
decision that has to be made if whether we want
the Diff.Path Filter Wheel to remain constant
w.r.t. the detector module when we focus 3) A
flex stage needs to be driven from its
geometrical center. This is not a possibility
with the present model. By using a set of linear
ball slides, this problem is eliminated 4) I am
assuming that this will be a non-motorized
mechanism, with just a knob, a dial and locking
device on the outside of the Vacuum Jacket. 5) A
resolution of 50 micron is easily achieved by
using a 1 mm pitch ball screw and incrementing
the drive every 9 degrees by means of a dial. It
can also be much smaller or larger, depending on
the need.
5
Here is a very unfinished idea of how the Ball
Slide Drive would look like for HiCIAO
6
THK Linear Ball Slide
G-10 Shear-web 4 _at_ 90 degrees Thermal Isolation
Ball Screw Location Schematic only
Light-Tight Feedthrough Not shown
Well also need a thermal insulation somewhere
along the shaft, not shown
7
Manual Focus Stage Can use an Indicating Dial on
outside for precise incremental translational
steps
Ball Screw Shaft exits here we can relocate the
Evacuation valve if needed