[Alastair, Aidan]

The Y-arm CO2 laser, which has not been getting injected to the CP, has now had its beam block removed so that we can perform the alignment proceedure.  The AOM drive from the DAC has a very low frequency pole that would stop us from injecting a large enough signal to do the alignment this way, so we have directly bypassed the module that has this filter.

Instead we put an oscillator directly on top of the enclosure set to 23.8Hz, 0.1V pk-pk, 0.1V offset.  This oscillator is running on AC power and has quite a noisy fan.  The oscillator is being fed through to the table and directly connected to the AOM driver, bypassing the DAC and all other electronics.

The laser has its rotation stage set to output the minimum power we could achieve (11mW) so this signal shouldn't be visible in the interferometer at the moment.  If it is critical to stop it doing this then the laser can be turned off from MEDM, however I would request that if at all possible we leave the laser running because I am still working on the long-term stability of the locking loops.

Installed the table interlock box from Richard on the shelf inside the X and Y tables.  I installed all the cables that seemed to be meant to attach to this.  Not sure if it was meant to have anything in the connectors for Status or Monitor

[Alastair, Aidan]

Today we added the chiller loop to the laser servo on Y-arm.  It takes an error signal from the PZT output voltage minus 35V, to set the PZT to the middle of it's range.  From the step function measurement the time constant for a temperature change request to actually change the laser temperature is around 110s.  Gain was taken from previous measurements of power as a function of pzt voltage and chiller temperature https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=11625.

We initially added a servo with unity gain at 0.001Hz, which should have given a reasonable phase margin, however we found that it was oscillating (very slowly), so we altered the unity gain down to 0.0003Hz and it now seems, from a few hours of operation, to be stable.

Attached is a graph of the 3hrs of laser power with the laser unlocked.  The pk-pk is roughly 0.17W.  Also attached is a chart of the laser with the PZT and chiller locked, showing pk-pk of around 0.02W, which in the full data plot looks to be the noise floor.  This plot starts just after the chiller servo has been engaged and shows it bringing the PZT voltage down from 55V, and actuating on the chiller temperature.

Attached are the OpLev trends from the past week. 

Laser Status:
SysStat is good
Front End power is 33.19W (should be around 30 W)
Frontend Watch is GREEN
HPO Watch is RED

PMC:
It has been locked 5.0 days, 22.0 hr 26.0 minutes (should be days/weeks)
Reflected power is 3.105Watts and PowerSum = 26.24Watts.

FSS:
It has been locked for 0.0 days 1.0 h and 43.0 min (should be days/weeks)
TPD[V] = 1.522V (min 0.9V)

ISS:
The diffracted power is around 7.575% (should be 5-9%)
Last saturation event was 0.0 days 2.0 hours and 10.0 minutes ago (should be days/weeks)
 

Activity Log: All Times in UTC (PT)

16:00 (08:00) Reset IPC error on H1SUSETMY
16:15 (08:15) Adjust ISS Diffracted power from -1.99v 9.4% to -2.0v 8.2%
16:20 (08:20) Goodwill on site for pickup – Bubba escorted
17:00 (09:00) Filiberto & Manny – Pulling cables at End-Y
17:03 (09:03) Christina – Opening OSB rollup door
17:51 (09:51) Corey – Working in the Optics Lab
17:57 (09:57) Chris & Joe – Beam tube sealing on X-Arm - ~800m from End station
18:00 (10:00) Filiberto – Back from End-Y
18:17 (10:17) Kyle – Going to End-X will be in compressor room
18:18 (10:18) Platt Electrical on site – Delivery for Richard
18:18 (10:18) Kiwamu – Transition LVEA to Laser Hazard
19:11 (11:11) Aidan & Nutsinee – Going into LVEA to IO table near HAM4 
19:48 (11:48) Joe & Chris – Back from X-Arm
20:00 (12:00) Dale – Big tour in the control room 
20:05 (12:05) Aidan & Nutsinee – Out of the LVEA
20:09 (12:09) Corey – Out of the Optics lab
20:10 (12:10) Dale – Another big tour in the control room
20:11 (12:11) Kyle – Back from X-Arm
20:11 (12:11) After initial alignment – Locked at DC_READOUT
20:15 (12:15) Start ASC-CHARD transfer functions for Jenne
20:21 (12:21) Lockloss – Unknown
20:37 (12:37) Kyle – Going to End-Y compressor room
21:11 (13:11) Locked at DC_READOUT for commissioning work
21:12 (13:12) GRB – Ignored alert due to status of IFO
21:20 (13:20) Joe & Chris – Bean tube sealing on X-Arm
21:30 (13:30) CW Injection running & CW Injection inactive messages
21:57 (13:57) Kyle – Back from End-Y
21:59 (13:59) Aidan – Going into LVEA
22:15 (14:15) Turn over to Travis
 

End of Shift Summary:

Title:  02/01/2015, Day Shift 16:00 – 00:00 (08:00 – 16:00) All times in UTC (PT)

Support: Jenne, 
 
Incoming Operator: Travis

Shift Detail Summary:  After running an initial alignment relocked the IFO at DC_RREADOUT for commissioning work. Started TFs for Jenne. Lockloss after about 10 minutes not related to Jenne’s TFs. Relocked at DC_READOUT. Jenne is running her TFs. Hand off to Travis. 

We had two occassions on Sunday where CRC errors showed up on certain front ends. Sunday 07:12 PST a single error showed up on some SUS, and ISI models, plus PSL DBB. Later at 18:05 PST all PSL models showed 8-10 errors. Normally CRC errors would be associated with model restarts, but no restarts happened on Sunday.

Attached are spectra comparing the SUS ETM L3 LV ESD channels from lock segments before (Jan 24, 2016 03:35:00 UTC) and after (Feb 1, 2016 01:50:00 UTC) the ESD Driver update last Tuesday alog 25175 (and the subsequent ESD fixes on Wed 25204).  Before the install, the channels looked like ADC noise, while they look live now.  The ETMx plot is included, but of course the ETMx ESD is not ON during either lock stretch, so all the plot really says is that something happened to the channels.  Whether or not the ETMy channels look like they actually should, according to various ECRs, is to be determined.

Feb. 1 2016 18:31 UTC Stopped Conlog on conlog-test-master. Had been started 19:42 UTC Jan 27 2016 (alog 25201). Shutdown conlog-test-master to install Spectracom card.

Kiwamu transitioned the LVEA to laser hazard

Pulled in new CPS Sync cabling from SUS-R1 to CPS units on BSC10.

Work still needed for install (EX/EY):

1. Install fanout chassis in SUS-R1
2. Run RF cable from Electronics Ebay to VEA SUS-R1 (71MHz)
3. Modifications to some of the CPS units (Converting units from masters to slaves)

Aftef improving the angular decouplig and the feedforward, the noise curve looks quite smooth to me, except for a small bump betwen 15 and 20 Hz and some other bumps between 55 and 80 Hz, to be investigated.

So I played the noise slope fitting game, to see what kind of noise shape we would need to explain the curve. At high frequency there's shot noise (flat) and Kiwamu's 1/f noise. At very low frequency (below 14 Hz) the noise curve looks very steep, and it seems to be something like 1/f^9, although it's very difficult to properly estimate the slope here, it could easily be 1/f^10. 

What's most interesting to me is that between 20 and 40 Hz, the noise floor is explanable with a 1/f^4 slope. I find this interesting because it points to suspension displacement or actuation noise in the second to last stage, for example excess noise in a DAC or coil driver in one of the test masses, or even in the BS.

Caveat: this is just a hint, the slopes and amplitudes I estimated might be very wrong, and there's no real indication that we only have three or four separate noise contributions. 

P.S. I wanted to upload the MATLAB fig file, but it's 21 Mb and so it seems I can't attach it here.

SEI – OK
SUS – Charge measurements
CDS – OK
FMP – Final carpet installation on Wednesday. Ongoing shimming the LVEA main crane. 
VAC – OK
PSL – High Power checkout work 
TCS – Guardian updates, Check out and commissioning. Prep work to turn on TCS-Y laser
General commissioning work continues. Commissioning meeting at 09:00 in control room
Outreach – Dale will conduct two tours through the control room around noon 

Outstanding work permits were reviewed. 
Reviewed planned work for Tuesday maintenance 

Attached are 14-day plots from turning up the front end laser pump diode current(s) and adjusting their
temperatures.

Note that even though the NPRO output power plot reads that the NPRO power is ~0.81W.  As measured by a
power meter placed after the phase-correcting EOM, the power is 1.46W.  The NPRO power monitoring photodiode
measures the power into the power amplifier.

Diodes 1 & 2: 51 A -> 55 A
Diodes 3 & 4: 51.6 A -> 57 A

Diode 1: 17 degC -> 16.5 degC
Diode 2: 17.5 degC -> 16.5 degC
Diode 3: 18 degC -> 16.5 degC
Diode 4: 18 degC -> 16.5 degC

             Transition Summary:
Title:  02/01/2016, Day Shift 16:00 – 00:00 (08:00 – 16:00) All times in UTC (PT)
	
State of H1: IFO unlocked – TCS commissioning work underway. Working on relocking.  

Outgoing Operator: N/A

No restarts reported for all four days.

I remeasured the 45 MHz phase noise coupling into DARM, this time with broadband excitation. No surprises here; it looks the same as the swept-sine TF that we took before O1 (20783).

Setup is similar to the previous measurement, although in this case the PLL has a UGF around 20 kHz, so that the control signal going to the IFR can be read out directly in order to get the frequency deviation.

We have had multiple locklosses today from the beamsplitter coil driver switching.

This is puzzling, since this step was largely unproblematic during the run.

Today I've been working on the guardian controlled laser pzt servo.  Using the Y-arm laser guardian can now scan the PZT, pick a locking point, calculate the slope at that point and use this to set the gain for the servo.  The servo itself has a unity gain frequency of 0.5Hz and 1/f below that.  After picking a locking point guardian sets the PZT to that voltage and waits for several seconds to allow the laser thermopile to come into equilibrium before re-measuring the power output which is then fed to the power setpoint. The servo is then engaged.  This gets around problems that I was having where using the value taken directly from the power to voltage curve would cause a small but unmanagable offset in the setpoint at the point where the servo was engaged.  The servo can cope with positive and negative slopes to the curve which reduces the number of times we will need to step the chiller temperature when trying to lock.  We may want to do a little averaging across nearby points when calculating the gradient to get the servo gain, because I did see some instances where this seems a little higher than we might want, which could lead to an unstable value being used.

The first graph attached shows two cycles of using guardian to lock the laser, with graphs for the PZT voltage (effectively the control signal) and the power output (effectively the error signal).  The second graph shows the data for power as a function of pzt voltage that was collected by guardian during the locking process.

I also ran a step function on the chiller to look at the time constant for the water to reach the laser (see attached graph).  It came in at 110s, which is similar to a measurement made at LLO.  We will use this to pick the unit gain frequency for the chiller servo loop.  The laser took a significantly long time to come to equilibrium, though this is because the step made was large.

I've been working on the Guardian script for locking the CO2 lasers.  It now has the following states programmed:

DOWN : Resets the laser pzt position to center. Resets the chiller temperature to 20C.  Turns off all servos

FIND_LOCK_POINT : Scans the internal pzt of the laser while measuring the power output using the thermopile.  The thermopile is a little slow, so this takes a few seconds to do.  It then looks at the slope of the resulting curve to work out if there is a suitable place to lock.  It can lock to a positive or negative slope.  If there is no good slope then it steps the chiller temperature by 0.03C (we may want to increase this) waits for 4minutes because there is a significant time lag (this may be too short to reach equilibrium temperture) and then retries to find a good point to lock the laser.  It finishes by setting a setpoint value for the desired laser power and leaves the PZT at the voltage corresponding to this power.

LOCK_LASER: Engages an integrator between the thermopile readout and the PZT.

RESET_PZT_VOLTAGE : Slowly hands off the DC offset in the PZT voltage from the offset box to the integrator. The offset ends up at 37.5V, which is the centre of the PZT range.  This offset plus the integrator output will now correspond to the PZT voltage for the desired laser power.

ENGAGE_CHILLER_SERVO:  The voltage from the PZT integrator is used as the error signal to drive the servo for the chiller.  The servo is engaged and gains are set.

ISS_ENGAGE : We don't yet need the intensity stabilization system so this state is just bypassed

LASER_UP : This state will be used to monitor the system while in use, looking to see if the power output of the laser exceeds certain boundaries, or whether the laser PZT reaches the limits of its range, which would indicate that the servo has lost lock on the laser.

We still need to setup the gains on the integrator stages for the laser pzt and the chiller.  The chiller one is particularly awkward to monitor because the unit gain frequency is so low.  The guardian script is currently located in the TCS folder  /opt/rtcds/userapps/trunk/tcs/common/guardian/TCS_CO2.py