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.
- 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
Four M10 eye bolts
M8 SDC bolts? to tighten the top plate to the stage body are shortened!
- Markers (black and white)
- Four clean slings (from Hirata-san)