eason's oh-oh mirror

Eason, Dale (deason@msmsmtp.StPaul.NCR.COM)
Fri, 21 Apr 95 13:41:00 CDT

As you all might recal I was trying to repolsih a mirror that had about 3x overcorrection. I was not getting any reliable results from my polishing. After analysis and recomendations from folks on this list I enlarged the tool to the full size of the mirror. Don't know what I was thinking when I decided to use an under sized mirror. That just made the hole deeper.

Anyway the new full sized lap didn't seem to be doing anything either. So I decided to use more pressure and more cerium oxide and polish, polish, polish at the .7 radius zone to lower it. Well that did it. I now have a rippled mirror with two concentric curves. There is the old curve in the middle of the mirror where I did not polish much and the new curve starting just inside of the .7 radius. The Foucault shadow shows it quite well. The zone mask does not have the resolution to see this ripple but the second zone is hard to null since it has both positive and negative slopes. The test reduction program now calculates I am down to 1/2 wave error.

Thus the mirror is improving. My task now is to smooth and remove the ripple and other deformations I caused by the heavy pressure. At least I'm learning and know that I can change the figure by polishing.

Dale