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Message ID: 2964     Entry time: Fri May 21 00:51:06 2010
Author: Jenne 
Type: Update 
Category: IOO 
Subject: First MC mode measuring (hopefully) done 

[Jenne, Kiwamu, Steve]

Round 1 of measuring the MC mode is pretty much done.  Yay.

Earlier today, Steve and I launched the MC beam off the flat mirror just after the Faraday, and sent it down toward ETMY(new convention). We ended up not being able to see it all the way at the ETM because we were hitting the beam tube, but at the ITM chamber we could see that the beam looked nice and circle-y, so wasn't being clipped in the Faraday or anywhere else.  To do this we removed 2 1inch oplev optics.  One was removed from the BS table, and wrapped in foil and put in a plastic box.  The other was just layed on its' side on the BS table. 

I then took the beam out of the BS chamber, in order to begin measuring the mode.  I left the flat fixed mirror in the place of what will be PZT SM1, and instead used the PZT mirror to turn the beam and get it out the BS chamber door.  (Thoughts of getting the beam to the BS oplev table were abandoned since this was way easier, since Kiwamu and Steve had made the nifty table leg things.)  Kiwamu and I borrowed an 2inch 45P Y1 optic from the collection on Koji's desk (since we have ZERO 2inch optics on the random-optic-shelf....no good), to shoot the beam down the hallway of the Yarm (new convention).  We used the beam scan on a rolling cart to measure the beam at various distances.  I made some sweet impromptu plum bobs to help make our distance measurements a bit more accurate.

We stopped at ~25 feet from the BS chamber, since the spot was getting too big for the beam scanner.  If it turns out that I can't get a good fit with the points I have, I'll keep everything in-chamber the same, and do the farther distances using the good ol' razor blade technique.

I have measurements for the distances between the beam scan head and the opening of the BS chamber.  Tomorrow, or very soon after, I need to measure the distances in-chamber between the MC and the BS chamber opening.  Plots etc will come after I have those distances.

Next on the to-do list:

1.  Measure distances in-chamber for first mode scan.

2.  Plot spot size vs. distance, see if we need more points. Take more points if needed.

3.  Put in MMT1, repeat measurements.

4.  Put in MMT2, rinse and repeat.

5.  Move the PZT mirror to its new place as SM1, and figure out how to connect it.  Right now the little wires are hooked up on the BS table, but we're going to need to make / find a connector to the outside world from the IOO table. This is potentially a pretty big pain, if we don't by happenstance have open connectors on the IOO table.

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