Kiwamu with remote help from Cheryl

As a part of the high power prep, I did three things this morning:

• Scan with an IR viewer to make sure there is no stray light on IOT2L and ISCT1.
• Power budget of IOT2L and ISCT1 to check the power level at various place.
• Attempt to search for the PRM parking beam.

Stray light:

I looked around the inside of the IOT2L and ISCT1 enclosures with an IR viewer to look for a stray light which needs to be properly dumped. I did not find a stray beam and therefore I didn't have to newly install a dump.

Power budget:

See the attached. When I made the measurement on IOT2L, I intentionally misaligned MC2 in order to have high and stable laser power on the IOT2L. As for ISCT1, I misaligned PR2 to avoid a fringe while maintaining the PRM reflection. Note that the IMC incident has been 1 W (see alog 9306) these days and during these measurements. Because the POP beam was so dark, I didn't even attempt to measure the power. Instead, I made a back-of-envelope estimation of the maximum power in the POP path with an assumption that the power recycled Michelson is locked.

Power at POPAIR_A (or POPAIR_B) = (1 W incident on PRM ) x (60 power recycling gain)  x (250 ppm PR2's transmissivity) x (90% BS in HAM1)  x (50% BS on ISCT1) = 6.75 mW

Of course, in reality, it must be smaller than this due to losses and etc.

Search for PRM parking beam:

Because we didn't check the parking beam during the last vent and also readjusted the alignment of the input optics recently, we need to find a good alignment for PRM again which gives us a parking beam coming out through the top view port of HAM2. Since a CCD camera was already mounted on the viewport, I used it to see if I can find the beam. I tried the good PRM biases (P=-330 and Y=-6100) that was established back in April (see alog 6168). Also, I enabled AWG and shook PRM in both pitch and yaw in order to somewhat expand the parameter region that I am scanning. However, I didn't find a beam or any sign of beam on the monitor. Also I turned the illuminator on and off to see if the CCD camera is actually looking at something useful, but the CCD kept showing a dark background regardless of the illuminator.

I am concluding that we need to remove the camera canister to see how the camera is doing and directly check the parking beam with a laser card or IR viewer.