J. Warner, R. Crouch, J. Oberling

Took another look at WHAM1 ISI alignment this morning after the HEPI actuators were attached yesterday.

The total station occupied monument LV25 and we used LV26 as the backsight.  The autolevel was placed sighting 171.9 mm on the scale we attached to height mark 600, placing it +100.0 mm above the ISI target z-axis position.  Measurements and calculations done as detailed in alog 84057.

We initially found the ISI a little off level, it was high on the -X side, so Jim did a small correction for that (it has to be small since there is much less range in HEPI with the actuators attached).  Final positional deviations from the ISI target of [-22726.7, 0.0, -201.9] mm are:

• X axis: +0.8 mm
• Y axis: +1.9 mm
• Z axis: +0.15 mm
• Yaw: 96 µrad CCW
• Level to within 0.38 mm

Tolerances for position are +/- 3.0 mm in all axes (reusing tolerances from aLIGO install); I don't find a yaw tolerance in my aLIGO install notes so we tried to minimize it while making other adjustments, I'd say <100 µrad is pretty good.  Jim says the level is good, so this ends IAS for the WHAM1 ISI for now.  IAS equipment has been taken down, although we still have it in the general area should there be a need to take another look at the ISI before the chamber is closed.

Based on the above deviations, the WHAM1 ISI coordinates in the LHO global coordinate frame are [-22725.9, +1.9, -201.75] mm.

Data and Calculations

Data and calculations for the above results.

X-axis Position and Yaw:

• +Y scale: +0.7 mm
• -Y scale: +0.9 mm
• X axis deviation: (0.9 + 0.7) / 2 = +0.8 mm
• Yaw: (0.9 - 0.7) / 2082.8 = +96 µrad -> 96 µrad CCW

Y-axis Position:

• Total Station EDM: 2011.2 mm
• Target: 2009.3 mm
• Deviation: +1.9 mm

Z-axis Position and Level:

• -X/+Y: 3.925"
• -X/-Y: 3.93"
• +X/+Y: 3.94"
• +X/-Y: 3.94"
• Average: 3.934"
• Scale target: 3.94"
• Z axis deviation: 3.94 - 3.934 = 0.006" -> +0.15 mm
• Level: 3.94 - 3.925 = 0.015" -> 0.38 mm