LAT Project: Mar.1 work

Dan Zuras

Well, here are the results.

I BELIEVE we took about 1.7 wavelengths of correction out of the 70% zone by over-smoothing.

I say, I BELIEVE, because my tester & Dave's gave different results. Let me show you how different.

Dave's radius was 33' 1 3/8" (397.375"), only 1/8th inch larger than before. My radius was 33' 2 1/8" (398.125"), 7/8 inch larger. Dave's is consistent with our previous measurements.

Dave's minimax wavelength error was 10.43 wavelengths, 1.67 LESS than before. Mine was 6.28, 2.48 BETTER than before. Mine is what we'd like to see but Dave's is consistent with the way the Ronchi appeared.

Dave's readings show less spread than mine. In fact, one of my datapoints (at 10.5") was so far off I had to throw it out in order to get one of the mathematical models to converge. Either the readings were so hard to read in my tester or I am not yet experienced enough in reading it.

Therefore, as an interim solution, I am throwing out the results of my tester and trusting Dave's. I make this choice because Dave's results are consistent both with what we did & with what the Ronchi appeared to show that night.

I include a table of both results at the end of this note in case any of you want to try your hand at the data. The data from my tester were taken in the negative direction of the micrometer so I have also included a column with all of those measurements incremented by 1" to make them comparable with Dave's. I have *ed the 10.5 point in my columns because I don't trust it. I believe there is some reason to doubt the points on either side of it, as well. I'm not sure.

BUT, one way or another, we have somewhere from 6 to 10 wavelengths to go yet. I believe we can STILL make progress on the edge. I think we just have to be more careful about the smoothing strokes.

As Anthony is out of town until Wednesday, I will talk with Dave about our next stroke until I hear from Anthony. (Anthony, call me. Dave & I have an idea for a safer smoothing stroke.)

Well, all, are there enough of you interested in polishing this weekend with all this uncertainty? If so, I'll call a session. If not, we could spend a week debating the shape of the glass before we resume. What say you all?

Dan

Results of 3/1/97 wire tests
  Barosso Zuras Zuras+1
Radius 397.375 398.125 398.125
35.5 1.0000 0.00000 1.00000
31.5 .9317 -.04840 .95160
28.5 .8541 -.09470 .90530
25.5 .7406 -.19520 .80480
22.5 .5529 -.32285 .67715
19.5 .4120 -.55275 .44725
16.5 .2584 -.69340 .30660
13.5 .1861 -.88765 .11235
10.5 .1135 -.82730* .17270*
7.5 .0589 -.95850 .04150
4.5 --- -1.11235 -.11235
1.5 --- -1.24750 -.24750

Dan Zuras

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