20180322
Today's activities
Workers: Yokogawa, Sugimoto, Akutsu
Yokogawa and Sugimoto did the fine tuning of the green beam alignment in the morning; see here.
- Afternoon we tried to align the BRT by using the green beam as a reference.
- But BS tended to get sudden excite!! so the beam tended to start dancing. It was so tough.
- In the beginning, the beam was, in average, found at the lower left within the 2nd BRT lens (looking at from the backside, so -Z (lower) and -X (left)).
- Using a laser leveler, we started with somehow finding which points the beam was going.
- Oh, I should bring the Mitaka setup!
Using a pillar as a reference, after the 2nd lens, it seemed
At 6x25= about 150mm away from the 2nd lens's leg: -X 10mm, +Z 17mm (in the interferometer global coordinate)with respect to the optical axis of the BRT (we need a reference, and used this, made by the laser leveler).
- At about 25mm away from the 2nd lens's leg: -X 10mm, +Z 13.2mm
- So it seemed shifted to -X, and tilted to pitch (17-13.2)/(150-25) = 0.0304 rad.
Considering (a) the input beam line is 1/300 tilted (in +Y direction lowered), and (b) the telescope is about 1/10 magnification (oh... what's the definition of "magnification!"), and (c) assuming the BRT was set horizontal, the pitch number above can be explained; 1/300-rad tilt will be enhanced by 10 times to be 1/30 = 0.0333... rad. (I did not remember well but the actual magnification was around 11 so it is very likely.)
- So we tried to tilt the BRT itself by about 1/300.
- We hooked up the BRT slightly after slightly loosen all the screws that fix the three legs of the BRT to the fixed stage.
- And then changed the length of each leg so that 1/300 tilted; the sticking-up length of the leg at (+X and -Y) = 16mm, (-X and -Y) = 16mm, (Center +Y) = 19mm.
- Then hooked down the BRT and tighten the leg screws.
- At least for pitch, the beam height seems ok. But our time was up and will check later in detail.
Some consideration for the ghost beam is here.
Next plan
- Measure the height with a laser leveler?
- Locate the BRT on the stage base on XXX as references.
- Make GPT on the optical table
- Make a model to drive signals from the TMS
- Check the response of the TMS by swinging BS, PR2, PR3... etc... with commissioning people
- Endのend用のフランジとりつけ。たぶん最後のほうで。
- そこのフランジにとりつける透過光用ビューポート。まだ柏にあるはず。
- 外側の光学定盤の上の取り回しを考えよ。
Wanted!
Four M10 eye bolts
M8 SDC bolts? to tighten the top plate to the stage body are shortened!
- Markers (black and white)
From VIS
- Four clean slings (from Hirata-san)