Sheila, Camilla, Georgia
This morning we took final (hopefully) profiles of the beam reflected off ZM5. We put the profiler on the -X side of the ISI again. We had some trouble getting a stable beam, with the power changing significantly. The OPO lock was a bit noisy, we saw high frequency noise on the error signal which corresponded to dips in the transmitted IR power. Sheila tweaked the gain of the OPO loop. We found that the power fluctuations were worse when the ISI was leant on, so perhaps this is causing the ZMs to swing around (the ISI is locked). We also found that touching up the ZM alignment helped stabilize the power.
First we took beam size measurements at two locations with the PSAMS voltages close to nominal:
V_ZM2_PZT = 97 V
V_ZM2_SG = 2.28 V
V_ZM4_PZT = 99.5 V
V_ZM4_SG = 0.2 V
V_ZM5_PZT = 117 V
V_ZM5_SG = 0.38 V
d_from_ISI_edge = [225, 290] mm
13.5_x =[2406, 2578] um
13.5_y = [2155, 2363] um
d4s_x = [2458, 2582] um
d4s_y = [2256, 2364] um
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Next we left the beam profiler at ~290mm from the ISI edge and swept the ZM4 voltage (with ZM5 at 117.5 V). All voltages are in V and beam sizes are in um. We did this so we can calibrate the strain gauge to mD.
V_zm4 = [100, 75, 50, 25, 0, 25, 50, 75, 100]
V_sg_zm4 = [0.2, -0.26, -0.85, -1.55, -2.29, -1.81, -1.22, -0.56, 0.14]
13.5_x = [2582, 2533, 2458, 2384, 2287, 2341, 2418, 2491, 2582]
13.5_y = [2347, 2309, 2229, 2155, 2061, 2125, 2190, 2260, 2341]
d4s_x = [2585, 2530, 2467, 2391, 2308, 2347, 2423, 2493, 2574]
d4s_y = [2366, 2321, 2246, 2166, 2080, 2131, 2195, 2270, 2348]
===
Finally we swept the ZM5 voltage and measured the beam size, still with the profiler in the same location
V_zm5 = [117.5, 100, 75, 50, 25, 0, 25, 50, 75, 100, 117.5]
V_sg_zm5 = [0.38, 0.05, -0.51, -1.17, -1.91, -2.72, -2.24, -1.62, -0.95, -0.25, 0.27]
13.5_x = [2582, 2513, 2382, 2260, 2126, 1983, 2063, 2188, 2327, 2467, 2568]
13.5_y = [2347, 2280, 2153, 2038, 1906, 1776, 1859, 1967, 2101, 2233, 2321]
d4s_x = [2585, 2508, 2394, 2270, 2136, 1993, 2075, 2195, 2332, 2469, 2573]
d4s_y = [2366, 2286, 2174, 2058, 1923, 1791, 1874, 1984, 2111, 2241, 2333]
In the afternoon we adjusted B:M4 to center the beam on ZM4. Photo of final alignment onto ZM4 attached. This was last looked at in alog 60420.
I tried the PAPR out this morning. Note to self: put the intake outside of my bunny suit next time to avoid constant low air alarms! Photo with Sheila and Georgia here!