Jeff and Andres finished the transfer functions of the 3IFO Q9 QUAD. Attached is the TF plot compared to the other 2 3IFO QUADs. Infact, this unit ALSO has the elusive 2nd pitch mode shifted up in frequency. In summary, so far all 3 of the 3IFO all-metal QUAD builds have this "feature".
Continuing the HAM6 HEPI Trouble shoot. Checked sensor readings against visual position and raange of motion. 2 vertical sensors readings where offset wrt their actual positoin enough to allow the sensor to touch its flag. This had to be corrected so I did that.
This shifted the computed cartesian position. I looked before and after the adjustments (Loops open all through out) and then adjusted the Target positions appropriately.
WHAM6 is back to Position control but without boost.
The V2 IPS continues to behave and I even jiggled the wires a bit this morning--Periodic maintenance: unplug & plug in cables repeatedly, fun!
Sudarshan, Gabriele
Since yesterday we were not able to move the beam on the ISS QPD or PDs using the picomotors, today we tried to use IM3 to change the beam position. In brief, we are able to see a change in the QPD signal when we move IM3, so it seems there is a beam on the QPD. We read a sum of about 830 count on the QPD, which corresponds to 0.5 V. The transimpedance should be 100kOhm, so the power on the QPS should be of the order of few microwatts, while we expect 1% of the total power going into the ISS box, which should be more like 0.1 mW.
We couldn't see any change in the mean value of the PD signals, however the RMS could be changed a lot, see the striptool trace. The initial position of IM3 was: PIT 55500, YAW 2600. The one corresponding to the largest RMS in the PDs was PIT 59500, YAW 1600.
The second plot shows a comparison of the PD spectrum (dewhitened) in the original position (red) and in the new position (blue). There is significantly more signal in the new position.
In summary
Aidan. Greg.
We removed the yellow viewport covers on HAM4 by the Hartmann sensor table (the acrylic covers are still in place). As expected, there was a leakage of the green ALS-X beam coming out of the HWSX and HWSY viewports (the HWSY green beam comes from the reflection of the ALS-X beam from the 50/50 surface of the beamsplitter, the HWSX green beam from the reflection of the ALS-X beam from the AR surface of the BS). The beams are incident on the apertures in the HWS table.
The beams are not centered on the apertures. However, due to the proximity of the HWS table to the H1-TCS-R1 rack (there's about 3" and a lot of cables between them), and due to adequate clearance of the green beams (~2") from the edge of the apertures, I elected not to move the table any closer to the rack to center the beams more than they already are.
HWSX:
HWSY:
The I/O chassis of h1seib2 died Tuesday evening, requiring a power cycle of the I/O chassis and h1seib2 computer.
The MC2 suspension have been misaligned by the guardian since 8:00 pm last night probably for the green light activity. I restored it at 9 am this morning.
We opened to both arms yesterday. The attached shows the result of exposing the chambers to the 80K pumps and the arms.
model restarts logged for Tue 23/Sep/2014
2014_09_23 02:28 h1fw1
2014_09_23 11:49 h1ascimc
2014_09_23 12:46 h1ascimc
2014_09_23 12:59 h1ascimc
2014_09_23 16:06 h1broadcast0
2014_09_23 16:06 h1dc0
2014_09_23 16:06 h1fw1
2014_09_23 16:06 h1nds0
2014_09_23 16:06 h1nds1
2014_09_23 16:07 h1fw0
unexpected restart of h1fw1. ASC-IMC model work with associated DAQ restart.
all the models on h1seib2 (Seismic Beam Splitter) stopped running around 7pm Tuesday night PDT. Looks like the IO Chassis is having problems.
Alexa, Keita, Gabrielle, Dan, Sheila
The bottom line: X arm is locked on green, we are having trouble finding the beam on ITMY and it might be helpfull to have a camera on ITMY tomorow.
Both PLLs are now working. Both beatnotes needed to be realinged. I reduced the power on the end Y BBPD, and realinged the laser green power monitor diode which was totally off.
We spent some time searching for the green beam on the ITMY baffle PDs, but didn't find the real beam, I think.
There is a beam which doesn't seem to have enough power, which can be found on PD1 at 2.2PIT, 7.3 YAW (20dB gain setting we get 3.6 Volts) PD4 at -97.8 PIT 74 YAW (3.6 Volts, 20dB setting) When aligned to the center of these points, there is no beam arriving on ISCT1, and we could not find any return beam on the ETM baffle PDs even after a long search. The ETM baffle PDs are working, since they clearly see the IR when PRMI flashes. I have left slow excitations on TMSY pitch and YAW hopping that at some point we will see light on the ITMY baffle PDs.
Other things today:
Keita and I briefly tried to move the bem spot on PR2, using the output matrix he described here : alog 13939
To do this we coped the gains from the opticalign filter banks into cal filters for pitch and yaw of iM4, PRM, PR2, and PR3. However, when I briefly tried moving the spot around I misaligned the cavity.
Gabrielle and I also tried locking DRMI using the configuration Kiwamu described from last night. We were able to see any lock longer than a few seconds.
PRMI however seems to be locking consistenly within a minute.
Thanks-H
Sudarshan, Peter, Keita, Gabriele
According to the electornic schematics, the ISS second loop transimpedance board has two parts:
With the present input power of 10 W, we should have something like 10 mW into the array, which means 1.25 mW per photodiodes, corresponding to about 1.0 mA of photocurrent. After the transimpedance we should get 1.6 V and 160 mV at the output of the board. This should corresponds to about 260 counts. However, we see that the RMS of the photodiode signals is about 17 counts and dominated by high frequency, while the mean value is ver close to zero, about 1 count (see second attachment, one minutes of data). It seems that we're not getting all the power we should.
We also checked in the electronics lab, with one spare board, that sending 1 mA at the input gives the expected signal levels both after the transimpedance stage and at the output. We also checked that adding a long cable at the input doesn't have any effect on the result.
Using the nominal whitening transfer function and transimpedance, we computed the calibration filters t be implemented in the PD filter banks. We don't want to have any 10 mHz pole, so we actaully fitted the whitening ransfer function between 1 Hz and few kHz, see third attachment (blue nominal TF, green implemented TF). Therefore, the PD_OUT signals are calibrated in mA only between about 1 Hz and 5 kHz. Below and above the signals are uncalibrated. This is expecially true for the DC level, which is not correct. Later on, once we'll have solved the missing power problem, we'll implement a calibration in units of RIN.
The result are shown in the forth attachment. The high frequency content of the 1-4 diodes (one board) is clearly different from the 5-8 diodes (the other board). We still don't know if this is due toa really different signal or to a different response of the board. Again, once we'll have solved the missing power problem, we'll see if this difference is still there.
Right now we are quite sure that the beam is not properly hitting the PDs:
So we wanted to move the beam using the two mirrors with picomotors. Of them, we were sure of the cabling of only the older one, which is the one closer to the ISS box and after the telescope. To make the story brief, we moved the picomotor by few 10000 steps in horizontal, bua saw no difference either in the QPD or PD signals. We could however see some "shaking" of the signals. Instead, moving in the vertical direction produced no result. So we're not sure if the picomotor is actually working. As for the second picomotor, we could not understand if it's cabled or not.
More investigations on the pico story tomorrow...
The water level is near the max line and does not appear to need to be filled.
J. Kissel, J. Warner, K. Izumi. Jim and I were working on ETMX; wiamu rolled over asking us what's up with HAM2 ISI. It had single-saturation tripped on actuators. We've got no idea. Our best guess is Kyle jumping around opening up the ARMs, but it's a terrible guess and probably not right. Sensor correction on HAM2 has been turned off since this morning. #fortherecord
HAM 2 tripped again later.
QUAD 06 (Q6) Phase 1B transfer function plots are attached. We had a hard time obtaining good coherence in the Transverse TF, so it is a bit hashy. Will try again.
Most notably is that, like Q8, the second pitch mode frequency is unexpectedly pushed upward on the main chain. Recall, we never found the mechanism to fix it on Q8. Interestingly, both the Q8 and Q6 assemblies are of the same batch of wires and are fresh builds, but by 2 different assembly teams, and on 2 different solid stack/test stand units. Q8 is an ETM type of QUAD while Q6 is an ITM QUAD, but both main chains have the same pendulum parameters - both are detailed in the 'wireloop' model.
The Q6 data is plotted as QUADTST.
We've checked that all wire diameters are as per the specs and that the wire segment clamps are seated properly on the masses. We've also checked that the wire segments have been assembled with the proper assymetry as per specs (looking for something obvious).
Attached are pix of this unit, in case someone wants to look at them. To me, they look just like the last few QUADs we've built, including Q8.
Maybe this is a long shot, but we've exhausted all the simple causes...could the top wire be the wrong material? If the modulus of elasticity was higher, within a factor of 2 from where it is supposed to be, that would explain this strange pitch mode.
One way to test this is to measure the violin modes of the topmost wire in situ and see if it is right. Or maybe more simply, cut some wire from this wire stock, hang some wieght off of it, and measure its violin mode.
The correct 1.1 mm diameter wire should have a violin mode of
frequency in Hz = sqrt(tension/0.0067)/(2*L)
where 0.0067 is the mass per unit length.
For example tungsten has a modulus about 2 times higher than what we are supposed to have. If for whatever reason we ended up with a tungsten wire, it would have an in-situ violin mode in the low 200s of Hz, rather than the 332 Hz spec (much denser than the usual piano wire).
Or even more simply, you could weigh some length of wire. The piano wire should be something close to 7 g/m. If you get different value from that, then the wire is the wrong material.
To confirm Brett's latest suggest regarding the wrong wire: We have 2 rolls of 1.1mm diameter top wire here at LHO which could have possibly been used for QUAD builds. Both are labeled as the correct stuff. We weighed a 1m segment from each spool. One measures 7.1g, the other measures 7.3g.
To be continued...
Another sanity check:
The Top Mass blade sets used for these 3 pitch-problematic QUADs are as follows:
Q6 - SET 10
Q8 - SET 8 - although I can't find the actual records
Q9 - SET 2
Q7 - SET 7 - still to be tested, unknown pitch frequency TFs
The SETs go from SET 1 being the most STIFF to SET 16 being the most SOFT. So, the sets we are using for the 3IFO QUADs are somewhat scattered or in the middle of the pack. They are not all clustered at the soft end, nor all at the stiff end...
And here's the spectra of this Q6. Note, the lowest stage (L2) does not have flags during the all-metal Phase 1 assembly, so the spectra plots of L2 are junk.
And now attached are a damped TF from each R0 and M0. As we all have noted in SUS - damped TFs on Phase 1 test stands are not useful since the damping is a function of the code on the out-dated test stands and the loops are not tuned very well. Long story short, there is a little bit of damping evident, given whatever filters and gains are loaded, and we can see healthy excitations run through the suspension so all seems well with damping capabilities of Q6.
Alexa, Gabrielle, Kiwamu, Sheila
This morning we moved PRMI to the 3F sensors, we used a gain of 3 in the input matrix to move PRCL from REFL 9 I to REFL 27 I, and a gain of 15 to move MICH from REFL 45 Q to REFL 135 Q. This was locked from about 22:26:55 UTC (september 22) to 22:33:20.
We then tried to move on to DRMI but have struggled most of the day to get it locked. We locked it a few times this morning, (21:00 UTC) but haven't been able to recently.
Also, as is typical recently, the anthropogenic noise is higer durring the evenings than durring the day, there must be an evening shift of hanford work. Screen shot of the last week is attached. This pattern started in mid august and has been true since then.
After Sheila left, Jeff and I saw the DRMI locked for a minute or so at around 6:06 UTC. However, after this lock, the DRMI never caught a fringe again.
The settings at that point were:
Also, I experimentally had an off diagonal element of -1 in the REFL_A_RF9_I to SRCL element together with the usual REFL_A_RF45_I to SRCL element at that point. Since there was a 3 Hz oscillation in MICH when it was locked, I increased the MICH gain by a factor of three, but this did not help at all.
I did a quick comparison between the 'evening' (high BLRMS between 1 and 3 Hz as Sheila mentioned) and the 'night' (quiet time).
By looking at the ground, we do see some amplification in the spectrum around ~2.5Hz by almost a factor of 10. However, there is not a lot of power at those frequencies and this amplification doesn't seem to affect the optical lever motion (I looked at PR3).
I'll do a further analysis tomorrow and see what SUS and SEI are doing, but I wouldn't bet this is your issue so far.
I also don't think this is the reason we have not been locking DRMI, since th situation was similar on the nights we did lock, and the fringe speed is 1-2 fringes per second. It is just interesting that we are actually louder at night than durring the day.
