Gabriele, Dan, Sheila

• We have locked DRMI at 1 Watt.
• We got WFS loops running for PRX and SRY, and added to the guardian the Xarm IR locking and wfs for inital alignment.
• We have focused several of the cameras, and now have better views of many optics.

We did several things today and last night...

First we worked on focusing the cameras on the input arm, ETMX, and both ITMs.  Now we have a much clearer view of our interferometer.  I also copied the code to align TMSX using the GigE camera from the IAS guardian into the ALS guardian, and tried it out with the cavity locked on green.  This kind of works, although the camera centroid is noisy, the noise roughly coresponds to 3 urad of TMS angle.  We probably want to get a mask going on the camera to see if that helps. 

We are using refl WFS for SRY and PRX.  We also attempted this for MICH on the dark fringe, but the signal was too noisy to work well.  For all the asc loops, we used FM1+2.  For PRX we used REFL B 9 with a gain of -0.0003 for Pitch and 0.003 for Yaw.  For SRY we used REFL A 9 with a gain of 0.03 for both pitch and yaw.  All of these states are now added to the guardian currently called ISC_DOF ( we will think of a better name).  This currently has the states that were in the DRMI guardian that are actually used for initial alingment, plus the arm IR locking states.   The graph for this guardian is attached.

After running though the parts of the inital laignment sequence that we have working so far, we locked PRMI at 10 Watts, and steped the power down using the rotation stage, manually correcting the power in DC PWR IN using the offset, and increaseing our gains.  We locked 2.8 Watts with a PRCL gain of 50.4 and a MICH gain of 10, and at 1 Watt with MICH at 110 and PRCL at 22 (we measured the loops and adjusted the gains to keep our MICH ugf around 12 Hz and PRCL around 80Hz, suprisingly the PRCL gain had to be increased by less than a factor of 10 to keep the same gain with a factor of 10 decrease in the power.) 

We then took some guesses at the gains to use for DRMI at 1 Watt based on Anamaria's document, what we had originally used, and what we needed for PRMI with 1 Watt.  After some adjustment, we locked with the parameters shown in the screen shot.  DRMI was locked on the sideband at 1 Watt from about 1:57 UTC September 28th to 2:21 when we tried to change a filter and it dropped lock. 
 

Yesterday afternoon we reconnected the ADC to the whitened signals for PD5-8. Now the status is the following:

• PD1-4: we are acquiring the direct output of the transimpedance, before the whitening. We can use those signals to check the DC level, but we can't see the AC noise
• PD5-8: we are acquiring the whitened output of the boards. We can see the AC noise, but no DC signal

I wanted to compare the RIN meaured by the first loop photodiodes PDA and PDB with was is measured by the second loop photodiodes. However, looking into the way PDA_REL and PDB_REL are reconstructed, I found a couple of strange things, and I'm quite convinced that the estimated RIN was wrong. Peter King computed the whitening transfer function of the PDA and PDB box. Comparing this with what was implemented in the PD?_CALI_AC, I found a quite large discrepancy I could not understand. Therefore I implemented an inverse of the expected whitening, which is good between 1 Hz and few kHz, as shown in the first plot. I also found that the low pass filter used in the PD?_CALI_DC was giving me a strange notch at about 10 Hz in the PD?_REL signals, so I changed it into a simple low pass, as visible in the second plot. For both the AC and DC parts, the old filters are still there.

The second loop photodiode PD5-8 outputs are dewhitened as explained in a previous entry. The output is calibrated in V, and the DC level that we measured before changing the ADc connection is about 3 V.

The third plot shows the RIN as visible in both the first and second loop photodiodes when the first ISS loop is open. In particular, we see that the second loop photodiodes are in good agreement with the first loop photodiodes, at least above 100 Hz. This is a cross check that the calibration in terms of RIN is, if not correct, at least self consistent.

The fourth plot shows what happens when the first loop is closed. As expected the out of loop PDB shows a flat RIN that I guess should correspond to the shot noise level, even though I don't know right now how much pwoer is getting into the diode, so I can't teel if the absolute level is correct. Looking at the second loop photodiodes, it is clear that we have a huge excess of noise with respect to the level obtained at the output of the first loop. At this point we can't tell if this is real intensity noise, or just jitter noise that couples to the second loop PDs. Recall that we didn't optimize at all the coupling of jitter to RIN for the second loop photodiodes. For sure, there's still a lot of work to do...

model restarts logged for Fri 26/Sep/2014
2014_09_26 13:05 h1dc0
2014_09_26 13:07 h1broadcast0
2014_09_26 13:07 h1fw0
2014_09_26 13:07 h1fw1
2014_09_26 13:07 h1nds0
2014_09_26 13:07 h1nds1
2014_09_26 23:12 h1fw1

unexpected restart of h1fw1. DAQ restart to include TCS HWS channels and new DMT chan list.

1. I tuned up the input pointing ASC loop which I closed yesterday (alog 14162).
   • see the attached for the loop parameters.
2. Locked PRMI and found POPAIR_RF18 at a high value of 200 uW.
   • One difference from the past is that IM4 had been servoed to a small bias in pitch (~11000 urad) by the IM4/PR2 loop.

No working green WFS with centering yet.

1. WFSB segment 3 demod signal is a factor of 10 weaker than the others when the beam is centered.

Giving the WFS centering servo a YAW offset (+0.4 in YAW so the beam stays at -0.4) would recover the balance. But at that point we're already almost railing MCL PZT.

2. Difference between good alignment (H1:ALS-C_TRY_A_LF_OUT_DQ=870-900) and not-terrible (smaller than 800) is big on WFS centering.

We made the centering servo work when the alignment is not that bad, but later when I manually aligned the arm, the servo started railing.

So, one of the problems seems to be that we don't have much range for MCL PZT mirror.

The screenshot shows the demod phase setting and RF WFS error signal, and you can see that the WFSB seg3 signal is very small. The reason why WFSB spectra look washed out is because the WFS centering kept railing during the measurement (sorry).

Next step would be to go to the end station, manually releave the PZTs, and repeat the measurements. I'll leave the centering servo disabled for now.

Attached see the TFs--Comparing these to the most recent in the matlab SVN (August 2013,) these look just fine.  There is a new little extra wiggle on some dofs at 0.7 & 1hz that I'd say are the table top components.

Sure, I know Jim beat me but he's young..  Of course we were both waiting for the filter loading/saving scripts to get fixed.  In the end, Jim fixed them.

Anyway, I got the controller on HAM4 now too.  Attached are two plots of calibrated spectra, top from 23 Sept with the Level1 controllers and the lower from this afternoon with the Level3 controllers.  Certainly compromises in place but good between 1 & 10 hz.   I'll look for the plotting tool jim used to compare to HAM3.

LVEA is LASER HAZARD

08:00 Hugh running TFs on HAM6 - folks should steer clear of that are for the next several hours

08:18 Peter King out of LVEA

08:40 Danny out to West bay to work on quad. Also helping Aiden with removing viewport cover for more precision TCS alignment

08:53 Aiden out to HAM4 for TCS/HWS

09:29 Danny into LVEA- this time for real.

09:30 Mode cleaner locked on wrong mode. Re locked on correct mode

10:16 Andres to End-X to search for parts in lab

10:30 Sheila out to focus cameras. X/Y arm

11:03 Aiden back out to LVEA

12:36 Peter out to H2 enclosure

12:59 Sheila to X-End to focus camera(s)

13:04 DAQ restart

13:05 Andres back to End-X searcing for parts

13:15 Danny out to X-End to search for parts

13:45 Danny out to Y-end to search for parts

14:24 Sheila back from focusing cameras

15:00 Sheila - locked X-Arm and going out to focus cameras in corner

15:07 Andres - back from End-X

15:35 Jim reports that everything seems fine with HAM5 HEPI/ISI. Gaurdian was placed back into the managed state and it seems happy as well.

15:50 Robert to beam tube enclosure between Mid-Y and End-Y

Peter K, Sudarshan, Gabriele

All the eight photodiodes are now acquired with the temporary break out box, allowing us to measure the direct output of the transimpedance. 

We could finally find what we believe is the real beam, since we got high power on all photodiodes and also on the quadrant. However, we've not been able to find a position that simultaneously center the QPD and maximize all the photodiode signals. We can either center the QPD or maximize one or few of the photodiode signals.

For reference, we have now

QPD = 22000 cts, 13 V

PD1 = 4170 cts = 2.54 V = 2.1 mW
PD2 = 4500 cts = 2.75 V = 2.7 mW
PD3 = 4620 cts = 2.81 V = 2.3 mW
PD4 = 5000 cts = 3.05 V = 2.5 mW
PD5 = 4840 cts = 2.95 V = 2.4 mW
PD6 = 4320 cts = 2.63 V = 2.2 mW
PD7 = 5120 cts = 3.13 V = 2.6 mW
PD8 = 5000 cts = 3.05 V = 2.5 mW

There is an excursion of about 20% from the minimum to the maximum. For sure, the present position does not correspond to one that minimize the jitter to RIn coupling for each diode separately. We tested that adding a slow 1 Hz modulation  in pitch or yaw on IM3 does introduce a fluctuation in the PD signals. The effect is particularly large in yaw, and much smaller in pitch.

Installed new high level controllers into the HAM5 ISI this afternoon. After some normal amounts of fiddling I have them working about as well as HAM3 (see attached performance spectra, blue is HAM3, the unlabeled red trace is HAM5). There's no feed-forward or sensor correction installed yet, so there's probably room for improvement. But for the moment, I hope it's good enough.

Aidan.

I set the SYNC frequency (the frame rate) for the H1 ITMX HWS to 1Hz rather than the default 57Hz. This was done by accessing the serial port of the camera, making sure the frame rate was set to 1Hz and then entering the command wus to "write user settings" to the camera.

I confirmed this was working by rebooting the camera and verifying that the frame rate returned to 1Hz.

See the attached screen capture of the command window I used to do this.

(I also turned off the HWSX SLED).

Aidan.

I removed the LEXAN cover to help locate the conjugate plane of the HWS by the ITM. This test was performed in the following way:

1. Removed Hartmann plate from CCD to get a simple capture of the return beam

2. Added a 50mHz, 4 micro-radian amplitude oscillation to ITMX YAW

3. Captured a series of 100 frames on the HWS, running at 1Hz. Measured the centroid of the overall intensity pattern for each frame.

4. Plotted the centroid vs time. 

5. Determined the <pk-pk> size of the oscillation in the centroid in pixels.

6. Determined the conjugate plane of the HWS near the ITM (or conversely, the conjugate plane of the ITM near the HWS).

<pk-pk>*magnification_of_HWS_optics*pixel_size = oscillation size near the ITM

The goal was to move the HWS along the optical axis until the <pk-pk> size was minimized.

The best I could do was:

<pk-pk> = 0.2 pixels

M = 17.5x

pxiel_size = 12E-6m

Therefore the oscillation size (peak to peak) by the ITM is 42 microns. The peak-to-peak angular change is 16 micro-radians for the reflected HWS beam. Therefore:

the HWS is within 2.6m of the conjugate plane of the ITM.

7. The last step was to replace the Hartmann plate on the sensor and move it an additional 10mm along the optical axis. (The Hartmann plate is mounted 10mm in front of the CCD and this action places the conjuate plane on the Hartmann plate rather than on the CCD).

The X1 accumulation was done from July 29 through August 1.

I get the N2 leak rate as <6e^-9 tl/sec and the hydrogen outgassing as 1.1e^-14 tl/sec/cm^2.  Corrected to 20C the hydrogen outgassing will be less.

The N2 rate assumes all of AMU28 is N2 but much of it may in fact be CO.

The RGA calibration was assumed to be 319 torr/amp.

X2 accumulated from Sept 18 through Sept 22.

N2 leak rate is <4e^-9 tl/s

H2 outgassing is 5.9e^-15 tl/s/cm^2.

The RGA calibration is assumed to be 319 torr/amp.

No temperature data was taken for this module. My guess is the average tube temperature has been 25C.

These are working again. We needed to align things on the table, as it was previously done with some random alignment.

The filter gains are +500000 counts for WFSA PIT/YAW and WFSB PIT, but -500000counts for WFSB YAW.

UGF is 10-12Hz for WFSA and 8Hz-ish for WFSB with these gains.

DAQ was restarted. Two changes:

• H1EDCU_HWS.ini created and added to DAQ master.
• H1BROADCAST0.ini two additional PEM channels added, requested by John Z.

As preparation for automating the initial alignment, I did some things associated with the X arm locking.

(LSC-TRX_A_LF path was realgined at ISCTEX)

After the PSL light was locked to the X arm, I realigned TRX_A_LF path in order for LSC to be able to do triggered lock acquisition. The beam was already hitting the center of the bottom periscope mirror from the beginning. I steered the bottom periscope mirror and some optics in the down stream. I found that a lens had been taken out  presumably due to the previous QPD work in this past July (see alog 12672). There was a post holder and a base plate secured on the table in front of the bottom periscope mirror. Looking around, I found a 2 inch lens (PLCX-50.8-515.1-UV-1064) with a post laid on the table. So I inserted it to the post holder and looked this was the right lens as the beam nicely converged towards the photo-diode (Thorlabs PDA100A).

Also, I put a temporary steering mirror aside. This is one of the mirrors that Sheila placed in this past July (alog 12672) and has been blocking the PDA100A. The DC voltage coming out from the PDA100A was about 300 mV with a 00-mode transmitted light on it.  I did not check the gain setting of the PDA100A. The ADC count reached 1x10⁴ cnts when the arm was locked on a 00 mode. Probably we will need to decrease the gain of the PD or that of the interface box at some point in the future in order to aviod saturation.

In addition, I adjusted the trans camera. I needed to move a black-place beam dump closer to a beam splitter which is the one before the PDA100A. Then I steered the beam splitter and the angle of the camera to coarsely center the beam in the view. I could not identify the channel number for this signal at the video matrix in MSR. Looks like channel #53 is it, but it keeps flickering for some reason and therefore hard to tell. Though, a 00-mode beam was visbile ocasionally. We need to fix this in the day time tomorrow.

(IM4/PR2 alignment with REFL9 WFS)

Instead of aligning IM4 and PR2 by hand, I started doing it using the REFL WFSs. I used REFL_RF9_A and _B and they worked well. Once I zero-ed the electronics offsets in the RF9 demodulated signals,they started looking reasonable. I closed two loops by feeding the A_RF9_I signal to IM4 and the other to PR2. IM4 turned out to be a well-diagonalized actuator in the sense that it was able to actuate mostly on the WFS_A signals. On the other hand, PR2 had some cross-coupling which is not surprising at all. I need to work on this a bit more in order to have more diagonalized servos. I did not precisely adjust the gains. So these are the remaining tasks.

Anyway, closing the loops increased the transmitted light and reduced first-order coupling from angular fluctuation of some optics. Note that I had the DC centering servo running in order to keep the spot centered on both WFS_A and _B.

Baffle PDs, now with the correct labels:

Especially in pitch, these are rather different from what we found yesterday, which is not too suprising since we were hitting the ITM somewhere far from the center yesterday.  There is a beam at the end station coming back from the ITM, and some fringing at ISCT1.  To be continued....