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Mirror Cell

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I used the program plop to calculate the number of mirror supports needed and their positions. An 18-point support was found to be adequate. The first plan was to use a single plywood disc to hold all 18 points. I got as far as siliconing the mirror to the disc when reservations set in. I post to the ATM mail list confirmed my fear that this was unlikely to work.
{short description of image} The recommendation from the list was that an 18pt floatation cell was the only way. So out came the jigsaw and welder. The triangles are 6mm aluminium, the rest is steel. I found that printing the graphic output from plop onto acetate at full size helped when putting it all together.
The supports points were made with small copper discs with a small portrait on them (cost 1p each). The pivot rods are held on to the 12mm collimation rods by smaller bolts
Instead of using ball and socket joints to hold the triangles I used an idea from the ATM mail list of using nylon bolts. These allow a few degrees of flex without shearing
Another false start was had gluing the mirror to the cell. This led to astigmatic or triangular stars indicative of pinched optics. I have ended up using cork pads on the supports and holding the mirror in place with a sling. Also note the addition of a fan into the side of the mirror cell, another directs air onto the back.

 

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Copyright 2006 Steve Chambers. All Rights  Steve@pmdo.com

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