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