12:41 PST Geting started. Chanber open Measuring power in PWR into the IMC and REFL path on WEST side of HAM1. Closing light pipe on ALS. Mode cleaner to OFFLINE. Measuring input light. Standard Ophir Power Meter. (No power filter, overloading power meter) (Wild goose chase for power filters in the LVEA. Every one found is either broken or damaged.) #FIXME Moving to EAST side. Measuring power on REFL PATH measuring in front of LSC REFL B. Expect 0.625 % of beam coming back HAM2. 0.25 W * 0.00625 = 1.5 mW. Measured 0.7 mW. (half of what is expected) Turning of REFL DC centering loops. Measured upstream of WFS / LSC Beam Splitter. Measured ~2.7 mW Consistent with previous measurement, about 4 times the previous number. Not otherwise useful to debug now. Moving to beam size measurement. REFL DC WFS loops are back ON. Removed REFL LSC A/B beam splitter. Checked power on LSC REFL A, with H1:LSC-REFL_A_LF_OUTPUT. 1.5 mW. Consistent with previous measurement of REFL LSC A with 50/50 beam splitter in front of it (0.7 mW from above). Removing LSC REFL A WFS centering loops are going nuts. Turning off DC centering. RM watchdogs trip. Reseting WDs. Motion is large because Keita is still moving things around (ie installing BeamScan) Mounting Beam Scan into LSC REFL A position. Measuring beam profile. REFL WFS DC centering ON when possible. Fit number instead of the profile measureing (distance is front of head [closest to lens] to center of lens) Beam size: X 530 um / 575 um Y +/- ?? guassian 1/e diameter. profile: distance from lens to beam scan head: 188 +/- 1 mm Beam size: X 366 um / 400 um Y new distance from lens to beam scan head: 198 +/- 1 mm Beam size: X 192 um / 208 um Y new distnace from lens to beam scan head: 210 +/- 1 mm Beam size: X 447 um / 445 um Y new distance from lens to beam scan head: 245 +/- 1 mm shoot for 193 mm. with beam diameter beasplitter is 6mm thick (wedge?) average of beam diameters at 188 and 198 to get beam diameter at 193 mm: (367 390 528 573) / 4 = 464 um 464 / 2 = 232 beam radius at 193 mm. 2. mm photo detector / 0.464 mm = 4.31 beam diameters room between edge of photo detector and beam Struggling to determine the wedge on the beam splitter. determined wedge by looking at beam deflection on EAST wall with and without beam plitter in LSC PD path (without PD in place). No BS: position recorded With BS: position deflected South (-X IFO coordinates). This means wedge in the mount is horizontal, and thick side is +X/-Y, i.e. toward north-east. This is the correct wedge angle. Now installing LSC REFL A (PD placed in transmission) guestimate is that diode surface is 3mm from the front of the ring. the ring thickness is 8 mm. means diode surface is 5 mm away from the front of the case excluding the ring. pictures show RING then CASE From center of lens to front of diode case is 193 mm. (excluding the ring.) Placing LSC REFL B (in reflecting). Difficult to measure beam path length from beam splitter, so measured from baseplate of LSC REFL A to a bolt hole on A/B beam splitter. Then matched the that distance with LSC REFL B. LSC A/B Beam splitter happily placed. Now for alignment of beam splitter and PDs. Aligning LSC / ASC beam splitter onto LSC REFL A. Once aligned, receiving 0.8 mW. Good. Math checks out. Aligning LSC A/B BS to align beam onto LSC REFL B. Also aligned, gets 0.8 mW. Now to align REFL diodes such that reflection off of PD hits newly placed beam dumps. Success. (and two BSs going in to PDs to confirm that didn't move and all light is centered on PDs and beam dumps.) Now remeasuring distances between things. distance between: - lens and LSC REFL A: 193 +/- 1mm - LSC A/B BS Front Surface and LSC REFL B: 125 +/- 3mm discovered that's too close. also tough to measure - From bolt in face of beam splitter to case LSC REFL A: 125 +/- 1 mm - from bolt in face of BS to case of LSC REFL B: 129 +/- 1 mm This difference between A and B is because of the 6mm thickness of the BS. (path to A [in transmission] is longer) Everything's bolted down and secure. Measuring powers everywhere. LSC REFL A reports: 0.8 mW LSC REFL A measured with OPHIR (no filter): 0.73 mW LSC REFL B reports: 0.73 mW LSC REFL B measured with OPHIR (no filter): 0.66 mW Measuring power into IMC with ophir, having now found functional filter in LSB. Bringing mode cleaner to OFFLINE. Overfilling the ophir diode, so only getting 15-18 mW. Switching to measuring REFL beam coming into HAM2. IMC back to LOCKED. Still confused by power meter. Think we figured it out, but may have very large systematic error. Using one of the filters found from the LSB: REFL beam just out of septum window from HAM2 into HAM1: 227 +/- 50 mW (large systematic error) REFL AIR path: 4.1 +/- 0.5 mW One more attempt at IMC PWR IN. Mode cleaner OFFLINE. Measured: 234 mW. IMC PWR IN says 249 mW. Now back to LSC REFL A /B given that we think we understand the power meter. OPHIR in front of REFL: A 1 +/- 0.5 mW Diode itself reports: 0.8 +/- 0.01 mW OPHIR in front of REFL: B 0.87 +/- 0.5 mW Diode itself reports: 0.735 +/- 0.01 mW NOW ON TO INVESTIGATING REFL WFS A/B. Turned off power to WFS chassis. Swapped cables of REFL A with REFL B took ASD with power still off. references 0 through 7. File saved to /ligo/home/controls/Desktop/2018-11-17_H1ASC_REF_AB_ASD.xml Turned on power to WFS chassis. re-aligned RM1 and RM2 to get light on WFS PDs. Took ASD with power on and in-vac cables swapped. references 8 through 15. Double swap -- now A/b are swapped at the rack. Changed H1:ASC-REFL_A_DC_SEG4_GAIN from 2 to 1. Took ASD with power on and both in-vac and rack cables swapped. references 16-23 Turned on REFL DC Centering loops. took asd with power on, DC centering on, and both in-vac and rack cables swapped. reference 24-31 DC SUM values are 700 A and 800 B. Blocked light in the double swap configuration, and have found that with physical B blocked, digital A reported loss of light. number 1 is a. The invacuum DC cable was probably wrong. So we swapped the cable back at the rack. Leaving the cable swapped in vacuum. HOWEVER. We checked RF signals as well. Blocked physical B, and looked at RF9 in A and B. With physical B blocked, digital RF9 A dropped signal (and digital DC B dropped signal). Chosing lesser of two evils and swapping the in-vacuum cables back to original wrong configuration. However, during all of this swapping, both legs are working, so we leave REFL A DC SEG4 off. Verified that physical A is digital B and physical B is digital A. So be it!