arnaud.pele@LIGO.ORG - posted 23:15, Wednesday 11 December 2013 (8917)
RM2 TFs unchanged
[Dave Arnaud]
Following Stuart's change at LLO after he discovered a bug in the display of some DAC channels (see alog entry 10101) the directories containing the SUS_CUST_${sus_type}_DAC_MONITOR.adl files have been svn updated, and now displaying the right signal.
Angus, Travis, Gerardo & Alastair Removed test mass from suspension and stored in tin. Small chip on the side of one of the ears on this mass due to brush against structure on removal. After TCS had replaced ring heater we put the production ETMY into the suspension ready for full alignment tomorrow morning. We checked the profile of the fibres in storage and the following ones all look to have approximately the same stretch. S1301759, S1301769, S1301770, S1301771, S1301772 & S1301767. The first 4 of these are now at at end-Y ready for use.
Addressing "Bug 256", the pair of ring heaters installed at the pilot ETM were from Production Lot #1. These have been replaced with a pair of ring heaters from Production Lot #3. See also T1300463-v17.
(Alexa, Sheila)
1. Input to MPC @ MSR: 280uW
2. Output of MPC @ MSR: 240uW
3. To EX @ MSR: 170uW
4. Output @ EX: 45uW
5. Outpt of patch panel on ISCTEX: 42uW
6. On table @ fiber output: 25uW
This is not good. 
. The loss between 2&3, 3&4, 5&6 are much higher than expected.
If you are measuring the total power, then you might try mandrel wrapping the fiber at the input; it may be that you are measuring power from higher modes in the fiber that will dissipate rapidly in the first part of the fiber chain. A mandrel wrap will dissipate these modes early, so you will be left with a more accurate reading of the power that will propegate the full length of the fiber. This will be particularly true for 1064nm light; singlemode fiber is designed for 1310nm - for 1064nm, it will behave more like multimode fiber.
Even so, something looks particularly bad with the insertion loss for the jumper between the polarizer box and the patch to EX (2&3 in your list). That's probably a bad or dirty fiber.
(Corey, Gerardo)
- Transition of LVEA to laser safe, Justin.
- Chris W, ASC/LSC front end code, per WP4335.
- TCS clean up, Thomas.
- Sheila and Alexa, X-End station, ALS table work.
- Travis, Alastair, Angus, and Gerardo, to Y-End TM removal from monolithic.
- Filiberto, to LVEA, camera work, ITMY installation.
- Transition of LVEA to laser hazard, Justin.
- Restart of epics gateway.
- Mindy and Thomas, Y-End, TCS ring heater installation.
- Travis, Alastair, Angus, and Gerardo, to Y-End, ETM12 install in monolithic.
ETMy Ear Bonding Information: Ear 58 was bonded to side S3 on 9/23/2013. Ear 68 was bonded to side S4 on 9/24/2013.
(Alexa, Sheila)
We were able to get the retro-reflected beam off of ETMX back onto ISCTEX. We adjusted the PIT and YAW offset of the TMS to the following values:
YAW: -297 (originally -224)
PIT: -3 (originally -13)
ETM offsets remain off
We have improved the mode matching between the outgoing and reto-reflected beam by moving ALS-L7 two inches toward PZT 2. By looking at the iris with a viewer, the shapes and sizes of both beams look good and matched.
We have also aligned the retro-reflected beam onto the PD.
DTT templates for RM2 tfs have been modified to match with the model update. They are called and lived in :
/ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/RM2/SAGM1/Data/2013-11-23_2212_H1SUSRM2_M1_WhiteNoise_${L/P/Y}_0p1to50Hz.xml
The turbo was spun up around noon - setpoints have been restored, vent and purge valves have been closed, and the system is stable. Pressure is currently 1.5 e-5 torr.
The IMC wasn't locking when I came to the control room at 13:30 local. People told me that there was a Beckoff restart. So I burtrestored h1ecatc1plc2 to 9 am this morning. The IMC is now back to operation.
All the nds command line clients (such as minute_trend_cli, second_trend_cli, streamer_cli and others) have been recompiled to fix a bug in which channel lists were not written correctly. This resulted in an inability to accurately report values for any channel that wasn't a float data type. Any users of these tools should use the tools to write a new channel list. Also the Makefile was changed to allow compiling with Ubuntu 12.04.
Valved in the roughing pump at X end ~9:30.
Alexa, Sheila, Cryus, Dave, Arnaud
We went to end X to start working on the table there this afternoon. calibrated the PDs on the table, preparing to set up the PLL. Along the way Cyrus helped us with a problem connecting the End X beckoff computer to SVN (restarting the windows machine) and Dave restarted an epics gateway. We saw that we have half the fiber transmission in the wrong polarization, so we will need to adjust it in the morning. We tried to align the two beams to interfer on the beam splitter, but with only 10uW or so in the fiber beam.
We sent the green beam into the transmon, locked the QPD servos, and set up irises once the ETM and transmon offsets were restored. We then raised the front apperature of the EOM, where the beam seemed to be clipping. This greatly improved the beam shape going into the chamber. After that we looked for the return beam, and could not find it. Arnaud had a look at what might have changed for us. He saw a change of about 40urad in HEPI, but that doesn't seem like enough to explain us completely not seeing the beam.
ISC EX PD Calibrations
Fiber rejected polarization 20uW, 0.23V,30dB gain TI=2000 Ohms, meaning responsivity= 0.19A/W
Fiber transmission monitor- 40uW out of fiber, light on PD too small to measure (we are using the old measurement of the splitting ratio 6%) 0.03V, 2000 Ohms, 30dB gain, gives responsivity 0.208 A/W
Laser IR monitor 0.35mW on PD, 1.68V, 2000 Ohms, 30dB, 0.08 A/W. The beam splitter right before the PD has a spliting ratio of 0.55%.
Green laser monitor (this is the beam rejected from the Faraday, so the power observed here depends on any polarization drift as well). with 53 mW of532 coming out of the laser, we have 0.8 mW on this PD, so a splitting ratio of 1.9%
Fiber BBPD (Fiber A) 0.56mW, 2000 Ohms, no gain, 0.14V responsitivty of 0.125 A/W
[Mark B Chris W Arnaud]
After modifying the tip tilts model this afternoon, I adapted the adl files to match with the new channel names, in order to resurrect the medm screens. The filterfile, as well as the snap file were also adapted. The only thing missing in order for the system to work is to connect the masterswitch, which will be done tomorrow morning. Other than this, everything seems fine, cf screenshot
Details of the process :
* Created a htts folder in /opt/rtcds/userapps/release/sus/common/medm/
* Copied the 42 adl files located in /opt/rtcds/userapps/release/asc/common/medm/asctt in the new htts folder
* Modified their filename from ASC_CUST_TIPTILT* to SUS_CUST_TIPTILT*
* Modified the content of each of them by changing the ASC/asc occurences to SUS/sus and ASCTT/asctt to SUSHTTS/sushtts (except for the IOP channels which were unchanged)
* Modified the sitemap to point out to the correct adl files
* Modified the H1SUSHTTS.txt filterfile that has been generated when installing the model this afternoon, to make it match with the old H1ASCTT.txt filterfile thanks to some magic tricks from Chris
* Created a softlink H1SUSHTTS.txt -> /opt/rtcds/userapps/release/sus/h1/filterfiles/H1SUSHTTS.txt
Bonne nuit !
Now the master switch is connected, RMs medm screens are functioning, as well as the damping
I looked into IMC alignment changes from before we started the pump down, to the current position. What I found is that MC1 pointing has changed dramatically. Pitch is changed by 332urad, and yaw by 184urad, when comparing the optic as it hangs without any drive. MC2 has seen changes as well, but smaller, with ptich changed by 52urad and yaw 12urad.
The MC1 pointing changes reuslt in beam position changes of 5.3mm in pitch and 3mm in yaw, at 16m. Very signiicant.
| no drive to optics | change in optic position, 11/25 to 12/10, in um and urad | beam shift in position at 16m, in mm |
| MC1 - M3 | ||
| L | 1 | |
| P | 332 | 5.3 |
| Y | 184 | 2.9 |
| MC2 - M3 | ||
| L | -7 | |
| P | 52 | 0.8 |
| Y | 12 | 0.2 |
As noted in alog6341, the gain on the Dual PD Amp board was set to 30dB (photo 1). I have reduced the gain to 10dB (photo 2). However, I still see saturation at 10V in the external PD monitor. Tomorrow I will try reducing the gain to 0dB.
I have reset the internal PD gain to 30dB (since we were never saturating there), and set the external PD gain to 0dB.
For the external PD:
Transimpedance = 20kOhm
Responsivity = .268A/W
Power @ ext PD = 0.93mW (w/ a drift of 7% of the ref cav alignment)
Gain = 0dB
Volts = (resp) x (power) x (trans) x (gain) = 5V
...Ignore above calculation for external PD...
power before AOM :31.1mW
after single pass: 24.1mW 77% single pass effiicency
after double pass: 20.45mW 66% double pass efficiency
The beam position on the iris after the retro reflecting mirror has not changed.
I tuned the upper periscope mirror pitch, this brought the transmitted PD voltage back to 1 V.
We have 5.8 mW in the ALS path before the Faraday, 5.33 mW after the Faraday, 4.3mW going towards the fiber, and 1.04 mW going towards the fiber launch PD (external on the fiber dist box).
In this configuration, I measured ~3.1mW at the input of the ALS fiber distribution and 100uW at the MSR.
and the end station we see 40 uW coming out of the fiber, not really enough.