The mounting of C1 (the common
corrector) in its cell
Basic notes on C1
Material: Fused Silica, anti
reflection coated
Diameter 801.52 mm
Thickness: 12.19 mm (with about
0.13 mm of wedge)
C1 wil be bonded with an
elastomer ring to the steel ring shown in the above photo. This steel
mount ring will later be attached to the C1 upper cylindrical mount,
which is also shown above. The upper cylindrical mount was used as a
convenient work surface while building up the elastomer bond. Later,
at the telescope, the upper cylindrical mount will be positioned and
attached to the lower cylindrical mount, kinematically.
Ed Mannery carefully positions
the optic in the steel mount ring in preparation for the pouring of
the elastomer bond.
As the elastomer will readily
leak out of available openings in the channel, an initial pour is
made to build an elastomer seal at the interface between a removable
mylar gasket and the glass and also between the gasket and the steel
ring. This was begun on Thursday, October 23.
This seal will firm up over the
next 24 hours. The final pour will fill the channel to construct the
elastomer mount ring.
The Final Pouring
On Day 2, Friday, October 24, the
initial "sealing" pour had set up successfully, so preparations were
made for the final pouring.
The steel mount ring has radially
drilled access holes to allow for tooling to be inserted to
externally measure the position of the glass. As the elastomer
creates a strong bond with virtually anything it contacts and very
difficult to remove, it is important ensure the measurement points on
the glass are shielded from the material during the pour. In the
picture above polyethylene strips, which have been hot-melt glued to
cover the measuring point on the glass, project out from the edge of
the optic. We had earlier determined that polyethylene and mylar
separated easily from the elastomer.
Ed pours it in.
It has a consistency similar to
honey, so careful progress is made over about an hour to finish the
task.
By about 6PM on Friday, the
channel is filled to the appropriate level and left to cure over the
weekend.
On Monday morning the material is
well set and the bonding ring appears bubble free and quite nice. We
will let the material cure as long as possible before
shipping.
Date created: 10/24/97
Last modified: 10/24/97
Copyright © 1997, Patrick Waddell
waddell@astro.washington.edu