There is an exictation running on ITMX L2 Y, I would like to start locking the green arm, so I would like to stop this.
With the reduced pitch motion in the green arm, I tried again to use the pure PZT dither scheme in pitch too. (I used it for yaw from the start). That seemed to work just fine. So I disabled XPIT DOF1 and enabled XPIT DOF2. I disabled the arm locking for the night to finish taking Y2Y transfer functions for L2 for ITMX and ETMX.
Another PtoP measurement on the M2 stage of PRM was launched at around 1:15 AM. It is running on opsws8 (which is Kissel's favorite workstation).
The diag file is in the official place:
/ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/PRM/Common/Data/2014-01-25-H1SUSPRM_M2_PtoP_SweptSince_0p2to5Hz.xml
PRM:
We had to restart the measurement around 2pm because of a template bug.
But we put the Y2Y measurement in the automatic queue, so it should start as soon as the P2P measurements finishes.
BS:
- the BS P2P finished, the Y2Y is now in progress
PR2: the anti-dewhitening on the PR2 is different from the PRM, so the templates have to be adapted smartly. We haven't done any PR2 measurements yet.
ETM and ITM:
We started L2 Y2Y measurements for those two suspensions. THey are in diaggui's and need to be safed in the morning.
Kiwamu, Stefan We increased the input power to 10Watt. - We removed the lock from the rotational stage interlock. - We rotated the Laser Power rotation stage from 56.1 to 30deg, raising the power by a factor of 10. - The power levels IMC REFL and IMC WFSs were kept thge same by adjusting the lambda/2 rotation stage on IOT2L. We had and have 12mWatt on IMC REFL. - We reduced the analog electronic gain on MC TRANS by a factor of 10. - We verified that we now have 29.7mWatt on LSC-REFLAIR_A, and 30mWatt on on LSC-REFLAIR_B on ISCT1. - We confirmed that the IMC UGF is still 54kHz. - We updated the IMC Guardian to switch on all 3 stages, and increased the in-lock gain to 13dB. This left the phase margin at 26deg.
Next we fine-tuned the cross-over: - Lowered H1:SUS-MC2_M2_LOCK_L_GAIN from 0.2 to 0.1, - Increased H1:IMC-REFL_SERVO_FASTGAIN from -10dB to -6dB, and - lowered H1:IMC-REFL_SERVO_IN1GAIN by 4dB (from 13dB to 9dB in-lock, from -10dB to -14dB out-of-lock. This lowered the x-over by 4dB to 15Hz UGF. We did notice some "ring-up" tendency from the missed fringes during lock-acquisition at 10W.
Because the MC2 TRANS signal was not showing healthy signals probably due saturation in the analog chain, the guardian wasn't capturing a fringe with the trigger. So we changed the guardian script such that it looks at IMC-TRANS instead which is not saturating. The threshold is now set to be 500 counts. This seems working so far.
Here is another plot which is related to the crossover adjustment. There was a unwanted crossover bump at 20 Hz before the adjustment.
Blue curve: before the adjustment
Red curve: after the adjustment
Green curve: during the adjustment.
Another plot: OLTF of IMC after the power increment. As expected, the OLTF didn't change at all by the power increment.
Note that it might be too aggressive because of a shoulder at 200 kHz which is kind of close to the unity gain. If it turns out that this is not good, we can always disengage the boosts and decrease the UGF a little bit.
[Keita, Koji, Yuta] (written by Yuta, poted by Koji)
ETMY green transmissivity and reflectivity were measured to be T=31.6 +/- 0.2(stat.) % and R=67.8 +/- 0.3(stat.) %
at the incident angle of 0.4 +/- 0.1(sys.) deg.
From the incident angle dependence measurement, the trasmissivity at 0 deg was estimated to be T=31.4 +/- 0.4(stat.) %.
[Motivation]
We wanted to check the transmissivity and reflectivity of ETMY at 532nm since ETMX has lower transmissivity than designed.
[Method]
1. Injected the green beam of the Prometheus laser from the HR side of ETMY at the quad stand.
Measured the incident, reflected, and transmitted power levels with the OHIR power meter configured for the wavelength of 532nm.
Performed three sets of the measurements at the spots at the top part of the mirror horizontally separated by 1 inch
around the horizontal center of the mirror. The horizontal shift of the spots were
The incident angle was assessed by measuring the beam separation at reflection.
The beam separation was 0.5 +/- 0.1 inch at 36 +/- 1 inch away from the HR surface. The incident power was ~50 mW.
2. Rotate ETMY and measured the transmitted power and the beam separation at reflection. Repeat the measurement with different incident angle.
During the measurement, ETMY was kept inside the clean booth at the end Y station. The beam spot on ETMY was ~2 inch blow the top edge of the mirror.
[Result]
1. At the incident angle of 0.4 +/- 0.1(sys.) deg;
T = 31.6 +/- 0.2(stat.) %
R = 67.8 +/- 0.3(stat.) %
2. ETMYtrans.png shows the transmissivity dependence on the incident angle. By fitting the measured data with a quadratic curve, we get
T = 31.4 +/- 0.4(stat.) %
at the incident angle of 0 deg. The incident angle dependence was
k = -0.25 +/- 0.09(stat.) %/deg^2
[Wavelength dependence]
We can estimate the wavelength dependence of the transmissivity from the incident angle dependence.
The wavelength dependence can be expressed by
T = T0 + dT/dlambda * dlambda
When the incident beam has some incident angle, the effective thickness of the coating changes. Thus,
dlambda = lambda/cos(theta) - lambda = theta^2/2*lambda
where theta is the refraction angle incide the coating and
theta = theta_{in}/n_eff
when theta << 1. n_eff is the effective refractive index of the coating.
So,
T = T0 + dT/dlambda (theta_{in}/n_eff)^2/2*lambda
= T0 + k*theta_{in}^2
From the measurement of k,
dT/dlambda = 2*k*n_eff^2/lambda = -9 +/- 3(stat.) %/nm
Here, we assumed n_eff=1.7.
I will be working on the IMC characterization as a part of the 10 W prep. During the period, the IMC probably will drop its lock several times.
We are done. We excited the IMC many times during the period.
Green team-
The arm cavity is finally locking stably, thanks to the work of Sebastian, Hugh, Jeff and company to reduce our pitch fluctuations. Now we have about 5% fluctuations in the transmitted power that comes from pitch fluctuations, much better than the 50% we had this morning, and the cavity has been locked at least for 10s of minutes. The slow feedback is now on, controlled by the autolocker.
We get a max transmission of about 740 counts on ALS-C_COMM_LF, while the single shot beam stayed at 45 counts, which means that the on resonance/single shot resonance is 16.1, so we are getting 74% of the power that we would expect and probably have 26% of our power in higher order modes ( improved from 45% this morning). This may have been due to Alexa and I moving the EOM in our effort to reduce the RF AM. Maybe it is worth tweaking the EOM alingment when the cavity is locked to see if this is the sourcce of our mode mismatch.
I will leave the cavity locking with the autolocker on, until the red team wants to misaling it.
The X arm cavity stayed locked with green only for over 6 hours last night. Attached is a histogram of H1:ALS-C_COMM_LF_OUTPUT calibrated in uW arriving on ISCT1.
I updated the iscmodeling tools on the workstations in the control room by checking out them from MIT's cvs server. Jim secretly installed the cvs command only on opsws4 for me. So if one wants to update them in some future, he or she should run the cvs command on opsws4.
(Alexa, Sheila)
We began by misaligning ITMX. At which point our starting RF AM signal was -47dBm at 24.41MHz. We inserted a PBS before the EOM to ensure that we had optimized s-pol into the EOM. Then we adjustd the EOM stage such that the RF AM signal dropped to -60dBm. The Imon signal then had an RF AM offset of 2mV, with a peak-to-peak of 4mV at 500Hz (in comparison to alog 9434). The Qmon signal had an RF AM offset of 1mV with a peak-to-peak of 3mV.
We then examined the noise out of Imon with the cavity misaligned, and only saw a factor of 2 decrease at 100Hz compared to the previous measurement (alog 9436). This reduction could have also come from the improved modulation depth we achieved today. There is still too much noise...
Occasional unexpected CP1 level fluctuations previously shown to be the result of the filling of the portable LN2 dewars. Attached is the latest example. Only noteworthy when fluctuations reach alarm levels (~1/2 the time)
The h1dmt0 and h1dmt1 computers are in the process of being upgraded to Ubuntu 12.04. This will take a couple of hours.
The upgrade process has finished. John Z. will need to update the DMT software on both computers to finish the job.
Hugh, Sebastien
Position loops (UUG 5Hz) have been installed on HEPI-ITMX.
The design of those loops can be find in the SVN at:
/ligo/svncommon/SeiSVN/seismic/HEPI/H1/ITMX/Scripts/Control_Scripts/Version_5/GET_H1_ITMX_Controller.m
The function GET_H1_ITMX_Controller stores the zpk filters into a structure called FILTER_OUTPUT. This structure is used by the HEPI scripts steps 6&7 to generate the plots and saved the filters into the good format.
Sebastian and I looked at trends back during the day to set the Target positions for HEPI. We left the Pringle modes out of the loop for a while because they were generating large drives to the actuators. After a couple hours we saw the trends of the pringles not going anywhere fast so we set those targets and engaged those loops.
When I looked at longer term trends to make this log I see that the HEPI Location values were zero until Hugo and I worked on the position loops on the 16th and the input matrices were populated. The trends look very flat/stable until ~8pm 21 Jan. The ISC crew reports suddenly experiencing a sudden misalignment. They traced it to ITMx HEPI. Some confusion about whether or not they attempted to engage the uncommissioned HEPI loops but the point is, HEPI moved and stayed. They realigned the SUS and continued. So HEPI will stay here.
Attached is the current Cart_Bias for the Target positions. If you see the HP or VP numbers far from the Targets, know that these are AC coupled.
Done.
Daniel and I saved your measurements on the ITM and ETM. You have data down to below 0.2 Hz, and you are loosing coherence on the ITM anyway, so when we get down to the end station we will turn off your excitation.