40m
QIL
Cryo_Lab
CTN
SUS_Lab
TCS_Lab
OMC_Lab
CRIME_Lab
FEA
ENG_Labs
OptContFac
Mariner
WBEEShop
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40m Log |
Not logged in |
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Mon Jul 4 10:30:37 2016, ericq, Update, General, Preliminary vent plans
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Tue Jul 5 17:14:02 2016, ericq, Update, General, Vent progress 
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Tue Jul 5 19:10:41 2016, rana, Update, General, Vent progress
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Tue Jul 5 21:51:35 2016, ericq, Update, General, Vent progress
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Tue Jul 5 23:38:42 2016, gautam, Update, General, Vent progress - ETMX SUS Coil driver electronics investigation
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Wed Jul 6 22:58:01 2016, gautam, Update, General, Vent progress - ETMX SUS Coil driver electronics investigation
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Thu Jul 7 00:25:07 2016, ericq, Update, General, Vent progress - ETMX SUS Coil driver electronics investigation
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Thu Jul 7 10:49:03 2016, gautam, Update, General, Vent progress - ETMX SUS Coil driver electronics investigation
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Fri Jul 8 11:35:45 2016, gautam, Update, General, Vent progress - ETMX SUS Coil driver electronics investigation
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Fri Jul 8 11:48:09 2016, Koji, Update, General, Vent progress - ETMX SUS Coil driver electronics investigation
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Fri Jul 8 14:03:26 2016, ericq, Update, General, ETMX removed from suspension
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Fri Jul 8 16:33:26 2016, ericq, Update, General, ETMX removed from suspension
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Fri Jul 8 20:44:09 2016, Koji, Update, General, ETMX removed from suspension 6x
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Sun Jul 10 15:38:01 2016, ericq, Update, General, ETMX in guiderod/standoff gluing fixture 6x
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Tue Jul 12 16:08:00 2016, ericq, Update, General, ETMX ruby guided gluing
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Wed Jul 13 21:13:51 2016, Koji, Update, General, ETMX guide rod gluing / ETMY Magnet gluing 13x
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Thu Jul 14 22:29:57 2016, ericq , Update, General, ETMX guide rod gluing / ETMY Magnet gluing
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Fri Jul 15 16:23:51 2016, ericq , Update, General, Gluing setbacks 
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Tue Jul 19 16:39:29 2016, Lydia, Update, General, ETMX magnet gluing/guiderod excess glue removed 
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Wed Jul 20 13:58:55 2016, Steve, Update, SUS, SUS damping out of vac chamber   
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Thu Jul 21 17:01:59 2016, ericq, Update, General, ETMX magnet gluing/guiderod excess glue removed
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Fri Jul 22 23:03:23 2016, gautam, Update, General, ETMX suspension - progress    
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Sun Jul 24 03:43:56 2016, ericq, Update, General, Magnet positioning
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Mon Jul 25 13:01:49 2016, ericq, Update, General, ETMX suspension - progress    
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Mon Jul 25 13:47:19 2016, rana, Update, General, ETMX suspension - progress
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Mon Jul 25 17:01:54 2016, Steve, Update, SUS, ETMX suspension - progress
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Mon Jul 25 20:37:46 2016, gautam, Update, General, ETMX suspension - Side OSEM test
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Tue Jul 26 18:07:57 2016, gautam, Update, General, ETMX suspension - Further OSEM Tests
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Thu Jul 28 03:22:28 2016, ericq, Update, General, ETMX magnets re-reglued
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Thu Jul 28 13:49:44 2016, gautam, Update, General, ETMX magnets re-reglued 
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Thu Jul 28 17:48:17 2016, gautam, Update, General, ETMY LR magnet broke off
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Thu Jul 28 22:43:03 2016, rana, Update, General, ETMY UL magnet broke off
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Wed Aug 3 10:52:03 2016, Steve, Update, General, ETMY soaking dish  
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Fri Jul 29 03:32:30 2016, ericq, Update, General, ETMX suspended once more
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Fri Jul 29 13:17:34 2016, Koji, Update, General, Oven
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Thu Jul 14 01:00:33 2016, Koji, Update, General, ETMX ruby guided gluing
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Thu Jul 28 16:43:01 2016, Lydia, Update, General, ETMX aluminium standoff groove condition   
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Fri Jul 8 21:22:38 2016, gautam, Update, General, Vent progress - ETMX SUS Coil driver electronics investigation
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Wed Jul 6 09:34:26 2016, Steve, Update, General, PRM sensing voltage LR
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Wed Jul 6 19:36:45 2016, Koji, Update, General, SUS Vmon  
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Thu Jul 7 15:23:39 2016, ericq, Update, General, SUS Vmon
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Thu Jul 7 16:05:55 2016, Koji, Update, General, SUS Vmon
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Thu Jul 7 17:12:50 2016, Johannes, Update, General, Vent progress   
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Tue Jul 12 23:51:16 2016, Johannes, Update, General, Vent progress - ETMY inspection 
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Wed Jul 13 00:38:25 2016, Johannes, Update, General, Vent progress - ETMY attempted repositioning
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Tue Jul 19 13:21:42 2016, Johannes, Update, General, Vent progress - ETMY attempted repositioning
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Sun Jul 10 17:33:00 2016, ericq, Update, General, Vent progress
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Mon Jul 11 15:13:22 2016, gautam, Update, General, Vent progress: in-date First Contact procured
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Message ID: 12340
Entry time: Tue Jul 26 18:07:57 2016
In reply to: 12335
Reply to this: 12345
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Author: |
gautam |
Type: |
Update |
Category: |
General |
Subject: |
ETMX suspension - Further OSEM Tests |
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Today, we did the following:
- Once again, inserted all four face OSEMs till the sensor voltage readouts were approximately half their saturation value. The presence of some ferromagnetic material in the Honeywell components makes this tricky as each coil is coupled to the other three, but we were able to converge to a point where all the voltage readouts were oscillating around a mean value of ~40-60% of their maximum value, with all the damping loops OFF.
- Turned on all damping loops, and verified that the OSEM positioning was indeed such that the sensor readout is nominally around 50% of the saturation value. The air buffeting around the clean bench means that the damping isn't nearly as effective as it is inside the vacuum chamber.
- Attempted to increase the gain on the damping loops - we first switched out the Chebyshev low-pass filter in all the damping loops for something a little less aggressive, to allow us to turn up the gain. However, this experiment wasn't a success, when we turned the damping loops on, they were ringing the optic up.
- At this point, Eric checked the offset sliders (summed in via the slow system) and saw that they were not zero. We zeroed these, but naturally, they destroyed the OSEM positioning equilibrium we had established earlier. So we had to go back and re-position the OSEMs
- After re-centering the face OSEM magnets relative to the LED-PD pair, we insertd the side OSEM such that the side magnet completely occluded the PD. Interestingly, Eric noticed that the magnetic attraction between OSEM and magnets conspired to center the side magnet fairly well in the side OSEM, when it completely blocked the PD. However, when he returned the side OSEM coil to its nominal operating position of approximately half-blocking the PD, some minor misalignment was re-introduced (i.e. even when the optic was swinging mostly along the axis of the side OSEM, the voltage readout did not quite go down to 0).
- We then decided to compare the spectra for the error signals for the 4 DOFs with the current configuration (i.e. suspension clamped down to table top, optic freely hanging, all OSEMs reasonably well centered, and with the ETMX SUS model reverted to its normal state) to some reference (see Attachment #1). I initially thought I would wait for the optic to settle down a bit more before taking the spectra, but it doesn't seem to be showing any signs of getting any quieter in the last one hour. In Attachment #1, I have plotted as reference the spectra of the error signals from the early hours of 4 July 2016, at which point we were at atmosphere but the heavy doors were not yet off, so this is not really a fair comparison, but we don't really have a period in which the optic was exposed to the atmosphere and with the OSEMs in place, at least from this vent. Colors are identical for a given DOF, with todays trace as a solid line, and the reference dashed.
- We did not check the room available to install some shimming piece of metal in the side OSEM holder, as a possible solution to solve the misalignment problem. Steve has already found pieces of varying thickness, and they are soaking in acetone right now, we plan to air bake them tomorrow.
I will have another look at the spectra tomorrow morning, to see if the damping improves overnight. |
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