Wednesday, April 04, 2007

I've been a victim of specification creep

Sorry I haven't written in a while. I've been busy at work. The work has not been onerous but it has been primarily all on the computer. This has left me disinclined to spend my spare time on the computer to blog.

I've finished design on what amounts to a mirror positioned to look down a hole at a radioactive source. When I started I thought this would be a quick project. A mirror, a mounting bracket, done!

I started by talking to the research folks. Because the hole was oversized relative to the size of the window they wanted a liner to minimize the radiation streaming down the hole to the cold mirror side. It also needed a beamstop behind the mirror to stop the radiation coming down the hole. By the way shielding was needed on the other sides to stop any secondary scatter.

I designed that up and then went to operations. What I had now designed was intended to be assembled onto the hole when used. Operations didn't like it. They didn't want to perform any assembly in the vicinity of the hole. The radiation dose rate would probably be too high. They wanted something that could be placed into the hole as a single unit.

At this time research decided they wanted two mirrors - one silvered for visible light imaging and another gold for infrared viewing. The mirrors would need to be selectable without breaking the radiation shielding.

Now the design includes a selectable mirror, radiation shielding, an integral optical table, an X-Y translation stage for installation, rubber mounts to allow for minor misalignment, and a lift truck to handle the whole package.

So what started out conceptually has a simple mirror on a bracket turned out to take over a month to design. The drawing package is going out today for estimating. There are over thirty drawings in the package.


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