georgia.mansell@LIGO.ORG - posted 17:16, Wednesday 20 October 2021 - last comment - 12:12, Thursday 21 October 2021(60349)
HAM7 SQZ-IFO beam profile data
- This afternoon we made a two beam profile measurements, around ZM4 and ZM5, the data is recorfed below.
- Lee and Wen worked on placing the D path (QPD path) lens and beamsplitters, including dog-clamping the D:M1 and D:L1 bases.
- After the profile we started preparing to drive the ZM4 PZT. We noticed on the back of both P-SAMS chassises that they were (1) powered off and (2) the two-pin HV cable was disconnected. We saw an HV-looking cable floating around but wanted to check with Fil before plugging it in.
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Profile around zm4
d_zm4_to_pickoff = 180 mm*
*from zm4 suspension surface ~5mm behind optic
d_pickoff_to_ref_hole = 45 mm
d_mm = [175, 95, 265, 568]
a1_4s_um = [1770, 1730, 1835, 2055]
a2_4s_um = [1790, 1710, 1850, 2055]
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Post-zm5 beam profile
d_pickoff_to_profiler = 290 mm
d_zm5_frame_to_pickoff_mm = [85]
a1_4s_um = [3665]
a2_4s_um = [3680]
We profiled the beam by picking off just before ZM4 and measured at 3 points that would go through the suspension if not for the pickoff. I am getting the overlap of the SQZ A-path retroreflected beam as of ZM4 to be 99.2% matched with the target interferometer beam.
Using that baseline measurement, we then can propagate the beam to ZM5. We haven't used PSAMS PZT voltage yet, but Camille M's CIT measurements give 105mD CX on ZM4 at 0V, see E2100289.
Space is limited near ZM5 due to the SK path optics, but without the QPD/WFS in place, we deflect the beam down towards the D path and take a single measurement. We use the beam size on ZM4 and the single measurement before ZM5 to determine the beam mode on the ZM5 optic. So far, the data matches very well with the 105mD of defocus of ZM4.
HAM7_beam_profiles.png shows the data and measurements so far. We hope to actuate on ZM4 soon and add several more curves. We will then do ZM5. the ZM5 actuation curves are at E2100291.