Keita, Kiwamu, Sheila

This afternoon we aligned the beam for the ALS doubling path from the PSL through HAM1 and out to the viewport for ISCT1.  

When we began Kiwamu saw that the beam was entering the light pipe nearly at the bottom of the aperture on the PSL side, although it was too high inside the chamber.  The top mirror of the periscope is mounted so that it can only move vertically, so Kiwamu moved it up slightly.  After that the beam that we saw in the chamber was probably a reflection off of the sides of the light pipe, but Kiwamu was able to recover by steering to get a reasonable beam.  After walking the beam in this way, we arrived at an alignment where the top periscope mirror is at the highest position possible.  On the PSL side the beam enters the light pipe slightly low (~7mm) and to the west (~5mm) in the ~75 mm aperture.   At the viewport in HAM1 the beam arrives slightly to the east of the center of the viewport (less than 10% off center) and the height is adjusted so that the beam hits the steering mirror at its center.  we then adjusted the position of the steering mirror (moving it less than an inch to the east) so that the beam is centered on it in yaw, and centered on the viewport heading towards ISCT1.  

We also considered looking at the alignment of the IFO reflected beam using mode cleaner flashes, but Cheryl told us that that beam will be moved later anyway when IM1+2 are moved, so we held off.  The high power beam dump we did not install because it is not ready yet, a part is missing.