Todd informed me that the ADC Timing adaptor boards we had ordered arrived today. I had to solder on the components and connectors as per the schematic, though the main labor was in soldering the high density connectors. I then proceeded to shut down all models on c1lsc (and then the FE itself). Then classic problem of all vertex machines crashing when unloading models on c1lsc happened (actually Koji noticed that this was happening even on c1ioo). Anyways this was nothing new so I decided to push ahead.
I had to get a cable from Downs that connects the actual GS ADC card to this adaptor board. I powered off the expansion chassis, installed the adaptor board, connected it to the ADC card and restarted the expansion chassis and also the FE. I also reconnected the SCSI cable from the AA board to the adaptor card. It was a bit of a struggle to get all the models back up and running again, but everything eventually came back(after a few rounds of hard rebooting). I then edited the c1x04 and c1lsc simulink models to reflect the new path for the X arm ALS error signals. Seems to work alright.
At some point in the afternoon, I noticed a burning smell concentrated near the PSL table. Koji traced the smell down to the c1lsc expansion chassis. We immediately powered the chassis off. But Steve later informed me that he had already noticed an odd burning smell in the morning, before I had done any work at the LSC rack. Looking at the newly installed adaptor card, there wasn't any visual evidence of burning. So I decided to push ahead and try and reboot all models. Everything came back up normally eventually, see Attachment #1. Particle count in the lab seems a little higher than usual (actually, according to my midnight measurement, they are ~factor of 10 lower than Steve's 8am measurements), but Steve didn't seem to think we should read too much into this. Let's monitor the situation over the coming days, Steve should comment on the large variance seen in the particle counter output which seems to span 2 orders of magnitude depending on the time of the day the measurement is made... Also note that there is a BIO card in the C1LSC expansion chassis that is powered by a lab power supply unit. It draws 0 current, even though the label on it says otherwise. I a not sure if the observed current draw is in line with expectations.
The spare (unstuffed) adaptor cards we ordered, along with the necessary hardware to stuff them, are in the Digital FE hardware cabinet along the east arm.
Steve: particle count in the 40m is following outside count, wind direction, weather condition .....etc. The lab particle count is NOT logged ! This is bad practice.
We made a new flowchart of ALS autolocker. We added the additional step to find the beat note frequency. We have to find a way to read the PSL temperature. By reading the PSL temperature we can decide the sweep range for the end green laser temperature with the curve which measured in previous measurement (in this entry)
We have three thresholds of error signal. One is the threshold for checking the arms are stabilized or not. It should be some hundreds count. Another threshold is to check that the suspensions are not kicked. This should be some thousands counts (in flow chart, it is 2K counts). The other is to check the optimal servo gain. If the servo gain is too high, the UGF is also too high and we will not have enough gain margin. The error signal start to oscillate at the UGF. We will check this oscillation and find the optimal gain. In flow chart this threshold is 1K counts.
The expected error signals derived from the estimated free running error signals of the ALS.
1) Previously estimated free-running noise (blue)
2) Previous in-loop ALS error signal (red)
3) Estimated error signal with the new servo (green)
4) Out-of-loop noise of the ALS with the arm controlled with the IR PDH (black)
Now the error signal (green) is expected to be very white.
The suppressed noise between 3 to 20Hz are below the sensing noise level.
There seems a little excess at 24.5Hz and 28Hz. If it is limiting the RMS, we need to take care of them.
Here are the MATLAB scripts and LISO codes for all of these servo analyses
The new ALS/LSC servo was implemented for the X arm.
I'll upload more data later but here I make quick remarks:
- We need to give the gain of 12 to have correct UGF with the ALS.
- With this servo, the Xarm PDH lock oscillates with the gain of 0.02. We need to lower the gain to 0.015.
Also FM trigger should be changed not to trigger unused FMs (FM7/8)
New ALS servo performance
Comparison between the old (orange) and new (red). The new error signal (red) is suppressed like a white noise as expected.
Comparison between the out-of-loop evaluation (black) and the in-loop signal (red). Below 50Hz the out-of-loop is limited by the sensor-noise like something.
This out-of-loop stability was measured with the ALS stayed at the top of the resonance and calibrated the POX11 error signal.
New ALS servo with the LSC PDH signal. When the PDH signal is used for the control, FM4 is additionally used.
In this condition, the error signal was measured and calibrated into frequncy noise (Hz/sqrtHz).
By comparing the POX (with the new servo) and POY (with the old servo) signals, one can see that the new servo has better supression below 30Hz with almost no cost at ~100Hz.
I've installed a new 2pin lemo cable going from the CM servo out to in2 of the MC servo board, and removed the temporary BNC. I used some electrical tape to give the cable some thickness where the lemo head screws on to try to strain relieve the solder joints; hopefully this cable is more robust than the last.
I put an excitation into the CM board, and saw it come out of MC_F, so I think we're set.
As promised, I have made a final AP table drawing, including the MC camera relocation changes by Kiwamu. I have posted it in the wiki on the tables list, and on the AP table page I've attached the inkscape .svg I used to make it, if someone needs to do small modifications.
Attached is a pdf version of it.
1) REFL beam has been split into 4, to go in equal powers and equal beam size to the now 4 REFL RFPDs, 11, 33, 55 and 165. A lens had to be added for REFL165 because it's a 1mm PD instead of 2mm like the other 3.
2) MC camera has moved.
3) I've cleaned up most of the random components on the table, put them away, and tidied up the cabling.
I wanted to try out the ASS tonight, but I wanted some kinds of screens thrown together so I would know what I was doing. Turns out screens take longer than I thought. Am I surprised? Not really.
They're probably at the ~85% mark now, but I should be able to try out the ASS tomorrow I think.
The free running PSL+AUX beat frequency noise spectrum has been measured via PLL. AUX laser PZT PM and AM responses were measured too.
Rough notes about these measurements:
Laser -> QWP -> HWP -> PBS -> 10% BS -> Beat
3.4Vpp out of PD, (40% contrast)
20dB Coupler, output to analyzer, coupled output to Mixer (-a few dBm, didn't check specifically)
Mixer: ZP-3+, BLP-5.1 at output
LO: OCXO @ 36MHz 13dBm->5dB Att-> +8dBm LO at Mixer
Got ~65mVpp out of Mixer
Mixer out -> SR560, LP 3Hz, G=500 -> Pomona Summing node -> Laser PZT
~30kHz UGF ~30 deg phase
Spectra, OLG via SR785 taken with free running PSL, anthropomorphic temperature servo. Data sheet calibration used for PZT. SR560 output noise dominates over analyzer, mixer, PD. Spectrum looks ok, I think.
PM measured with AG4395. High impedance probe used for laser PZT, otherwise couldn't lock. PM calibrated via mixer voltage span for fringe-to-fringe.
PSL beam blocked, AUX power increased to read 8.0V, AM measured with AG4395.
AM/PM doesn't look to dissimilar to old measurements on wiki. ~230kHz looks like a fine modulation freq.
Still to be done to AUX laser:
- joint PSL/AUX temperature sweeps
- Output power vs. diode current
- Beam profile
I've performed the temperature sweep of PSL vs Innolight 1W AUX laser.
It remains to measure the output power vs diode current, and the beam profile. I will do the latter on the SP table where there is a little more space. Because we have 1W from this NPRO, the knife-edge method requires a power meter that has a large dynamic range and is sensitive enough to profile the beam accurately. After consulting the datasheets of the power meters we have available (Scientech, Ophir and Coherent) together with Koji, I have concluded that the Coherent calorimeter will be suitable. Its datasheet claims it can accurately measure incident powers of up to 100uW, although I think the threshold is more like 5-10mW, but this should still be plenty to get sufficient resolution for a Gaussian intensity profile with peak intensity of 1W. We also checked that the maximum likely power density we are likely to have during the waist measurement process (1W in a beam of diameter 160um) is within the 6kW/cm^2 quoted on the datasheet.
I made an Altium schematic for the microphone amplifier circuit for fabrication.
Two new BBPDs have been installed on the PSL table.
The first one was installed by Koji a few days ago, and I stalled the second one today.
They will serve as beat-note detectors for the green locking.
Next step : I have to lay down a long SMA cable which goes from the BBPD to the IOO rack.
Yuta and I bought some new BS mounts so that we could use the 4th port of the beamsplitters which are combining the PSL green and the arm transmitted beam, just before the Beat PD for each arm. I just placed the Yarm one, and have aligned the light onto both the Beat PD and the Trans DC PD.
I'll do the Xarm after lunch.
Here is a photo of the board inside the broadband photodiode (one of them) that I took from the Gyro experiment:
This PD is Serial Number S1200271.
We need to have a look at the schematic, figure out what's in here now, and then modify this to be useful (appropriate resonances / notches, as well as amplification) for POP 22/110.
General Remarks on the BBPD
- To form the LC network: Use fixed SMD inductors from Coilcraft. SMD tunable capacitors are found in the shelf right next to Steve's desk.
If the tuning is too coarse, combine an appropriate fixed ceramic SMC C and the tunable C (in parallel, of course)
- L1/C1a/C1b pads are specifically designed for an additional notch
- Another notch at the diode stage can be formed between the middle PD pin (just left of the marking "C3b") to the large GND pad (between C1a/C1b to C3a).
You have to scratch off the green resin with a small flat screw driver (or anything similar)
- A notch at the amplifier stage can be formed between the output of MAR-6SM ("+" marking) and one of the GND pads (left side of the "U1" marking)
- The original design of the PD is broadband. So additional notches on the diode stage provides notches and resonances.
Check if the resonances do not hit the signal frequencies.
- One would think the PD can have resonant feature to reduce the coupling of the undesired signals.
In some sense it is possible but it will be different from the usual resonant tank circuit in the following two points.
* Just adding a parallel L between the cathode and ground does not work. As this DC current should be directed to the DC path,
L&C combo should be added. In fact this actually give a notch-resonance pair. This C should be big enough so that you can ignore it
at the target resonant frequency. Supply complimentary small C if necessary to keep low impedance of the Cs at the target frequency.
(i.e. Check SRF - self-resonant frequency of the big C)
* Since the input impedance of MAR-6SM is 50Ohm, the top of the resonant curve will be cut at 50Ohm. So the resultant shape looks
like a bandpass rather than a resonance.
- So in total, simulation of the circuit is very important to shape the transimpedance. And, consider the circuit can not be formed as simulated
because of many practical imperfections like stray Ls and Cs.
I looked at the BBPD design so that we could make a POP22/110. It looks like it will be easy (I hope).
The first attachment shows the schematic with the RF notch modified to handle 55 MHz. As long as the capacitor in this notch can be kept to below 20 pF, it doesn't degrade the noise so much,
The second attachment shows the TF and input referred noise. We ought to be able to get 20 pA/rHz at the input to the first RF amplifier.
The LISO files are in the svn under liso/examples/aLIGO_BBPD/,
Later, if we have to notch more than just 55 MHz, we can add a notch between the 2 RF amplifiers as Koji has done for the REFL165.
[Jamie, Jenne, Koji]
We installed the new c1lsc and started the process.
We still need to configure bunch of the EPICS variables, matrices, and some of the filters.
This should be done in order to transmit the signals to the suspensions.
Jenne is going to work on this task tomorrow (Friday) morning,
and Koji will take over the task afternoon/evening.
We placed 3 new computers in the racks. One in 1X4 (machine running SCX) and 2 in 1Y4 (LSC and SUS). These are 1U chassis, 4 core machines for the CDS upgrade. I will be bringing over 2 IO chassis and their rails over tomorrow, one to be placed in 1Y4, and 1 in 1X4.
We still need some more 40 pin adapter cables and will send someone over this week to make them. However, once we have those, we should be able to get two to three machines going, one end computer/chassis and the SUS computer/chassis.
After tomorrow we are still going to be owed 1 computer, another dolphin fiber, a couple of blue boxes, and the LSC, IO, and Y end IO chassis. We also realized we need further fiber for the timing system. We're going to need to get and then run fiber to both ends, as well as to 1X3, where the LSC IO chassis will be.
We are now using the LIGO CDS SVN for storing our control models.
The SVN is at:
The models are under cds_user_apps, then trunk, then approriate subsystem (ISC for c1lsc for example), c1 (for caltech 40m), then models.
We have checked out /cds_user_apps to /opt/rtcds/.
So to find the c1lsc.mdl model, you would go to /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1lsc.mdl
This SVN is shared by many people LIGO, so please follow good SVN practice. Remember to update models ("svn update") before doing commits. Also, after making changes please do an update to the SVN so we have a record of the changes.
We are creating soft links in the /opt/rtcds/caltech/c1/core/advLigoRTS/src/epics/simLink/ to the models that you need to build. So if you want to add a new model, please add it to the cds_users_apps SVN in the correct place and create a soft link to the simLink directory.
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1sus.mdl -> /opt/rtcds/cds_user_apps/trunk/SUS/c1/models/c1sus.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1sup.mdl -> /opt/rtcds/cds_user_apps/trunk/SUS/c1/models/c1sup.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1spy.mdl -> /opt/rtcds/cds_user_apps/trunk/SUS/c1/models/c1spy.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1spx.mdl -> /opt/rtcds/cds_user_apps/trunk/SUS/c1/models/c1spx.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1scy.mdl -> /opt/rtcds/cds_user_apps/trunk/SUS/c1/models/c1scy.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1scx.mdl -> /opt/rtcds/cds_user_apps/trunk/SUS/c1/models/c1scx.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1mcs.mdl -> /opt/rtcds/cds_user_apps/trunk/SUS/c1/models/c1mcs.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1x05.mdl -> /opt/rtcds/cds_user_apps/trunk/CDS/c1/models/c1x05.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1x04.mdl -> /opt/rtcds/cds_user_apps/trunk/CDS/c1/models/c1x04.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1x03.mdl -> /opt/rtcds/cds_user_apps/trunk/CDS/c1/models/c1x03.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1x02.mdl -> /opt/rtcds/cds_user_apps/trunk/CDS/c1/models/c1x02.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1x01.mdl -> /opt/rtcds/cds_user_apps/trunk/CDS/c1/models/c1x01.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1rfm.mdl -> /opt/rtcds/cds_user_apps/trunk/CDS/c1/models/c1rfm.mdl
lrwxrwxrwx 1 controls controls 55 Apr 28 14:41 c1dafi.mdl -> /opt/rtcds/cds_user_apps/trunk/CDS/c1/models/c1dafi.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1pem.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1pem.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1mcp.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1mcp.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1lsp.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1lsp.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1lsc.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1lsc.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1ioo.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1ioo.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1gpv.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1gpv.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1gfd.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1gfd.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1gcv.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1gcv.mdl
lrwxrwxrwx 1 controls controls 54 Apr 28 14:41 c1ass.mdl -> /opt/rtcds/cds_user_apps/trunk/ISC/c1/models/c1ass.mdl
I've added a diagram in the wiki under IFO Upgrade 2009-2010->New CDS->Diagram section Joe_CDS_Plan.pdf (the .svg file I used to create it is also there). This was mostly an exercise in me learning inkscape as well as putting out a diagram with which lists control and model names and where they're running.
A direct link is: CDS_Plan.pdf
Here are the new calibration plots for my photosensors. These calibrations were done using a translation stage.
The linear region for the first photosensor appears to be between 15.2mm and 30 mm
The linear region for the second photosensor appears to be between 12.7mm and 22.9mm
The slope for both is -0.32 V/mm (more precisely, -0.3201 V/mm for PS 1 and -0.3195 V/mm for PS 2)
Awhile back we had requested a feature for the RCG code where a single file would define a memory location's name as well as its explicit hex address. Alex told me it had been implemented in the latest code in SVN. After being unable to find said file, I went back and talked to him and Rolf. Rolf said it existed, but had not been checked into the SVN yet.
I now have a copy of that file, called G1.ipc. It is supposed to live in /cvs/cds/caltech/chans/ipc/ , so I created the ipc directory there. The G1.ipc file is actually for a geo install, so we'll eventually make a C1.ipc file.
The first couple lines look like:
There are also section using ipcType IPC:
Effectively the ipcNum tells it which memory location to use, starting with 0x2000 (at least thats how I'm interpreting it. Every entry of a given ipcType has a different ipcNum which seems to be correlated to its description (at least early on - later in the file many desc= lines repeat, which I think means people were copy/pasting and got tired of editing the file. Once I get a C1.ipc file going, it should make our .mdl files much more understandable, at least for communicating between models. It also looks like it somehow interacts with the ADCs/DACs with ipcType PCI, although I'm hoping to get a full intro how to use the file tomorrow from Rolf and Alex.
Rana, Aaron, Gautam
The old Zojirushi has died. We have received and comissioned our new Technivoorm Mocha Master today. It is good.
Yehonathan and I began to put the electronics on Rack 1X3. To do this, we had to move the monitor over the the PD testing table. Before mounting the Coil Drivers, we added numbers to the spaces to follow the rack plan Koji has provided. The drivers which have been mounted are PRM (Slots 10,11), BS (Slots 15, 16), ITMX (Slots 26, 27), and ITMY (34, 35).
Gautam and I tested out the DAC that he installed in the latter half of last week. We confirmed that at least one of the channels is can successfully drive a sine wave (ch10, 1-indexed). We had to measure the output directly on the SCSI connector (breakout in the FE hard drive cabinet along the Y arm), since the SCSI breakout box (D080303) seems not to be working (wiring diagram in Gautam's elog from his SURF years).
We finished up making the new c1omc model (screenshot attached).
The new channels are only four DAC for ASC into the OMC, and one DAC for the OMC length:
I began moving the AA and AI chassis over to 1X1/1X2 as outlined in the elog.
The chassis were mostly filled with empty cables. There was one cable attached to the output of a QPD interface board, but there was nothing attached to the input so it was clearly not in use and I disconnected it.
I also attach a picture of some of the SMA connectors I had to rotate to accommodate the chassis in their new locations.
The chassis are installed, and the anti-imaging chassis can be seen second from the top; the anti-aliasing chassis can be seen 7th from the top.
I need to breakout the SCSI on the back of the AA chassis, because ADC breakout board only has a DB36 adapter available; the other cables are occupied by the signals from the WFS dewhitening outputs.
Yesterday, we installed some new DIN rail connectors at the LSC rack to provide 3 new outputs each for +24V DC and -24V DC. The main motivation was to facilitate the installation and powering of the differential receiving AA board. The regulators used inside the 1U chassis actually claims a dropout voltage of 0.5V and outputs 14V nominally, so a +/-15V DC supply would've perhaps been sufficient, but we decided to leave a bit more margin, and unfortunately, there are no +/-18V DC KEPCO linear power supplies to the LSC rack. Procedure:
The c1lsc frontend models crashed for some reason during this procedure. Now the c1sus frontend model is also behaving weirdly. It is unclear to me if/how this work would have led to these problems, but the temporal correlation (but not causation?) is undeniable.
I forgot to elog (bad Jamie) that I broke out the demodulator from the LOCKIN module to make a new DEMOD part:
The LOCKIN part now references this part, and the demodulator can now be used independently. The 'LO SIN in' and 'LO COS in' should receive their input from the SIN and COS outputs of the OSCILLATOR part.
The new EOM adapter plate and riser just got back from the shop. I just had Mike do the milling, and I'll drill and tap them tomorrow after the TAC. Then we can remount the EOM to see if stiffening the mount helps at all.
EOM is remounted on the fancy-pants new mount that I crafted. EOM is also aligned. 2 green mirrors (the first ones to see the beams coming onto the PSL table from the arm transmissions) had to be moved so I could fit the mount in, since the new mount is bigger than the old one. I put them back, and approximately realigned them, but didn't do any fine alignment. This must be done before looking at beatnotes again.
After playing with the EOM, the MC was flashing on higher order modes. The PSL beam has been realigned to make the MC lock on TEM00, and Suresh helped me center on the WFS and MC2T.
Things look okay for now. Next step: Kiwamu needs to find his happy mode cleaner place, and we'll realign the PSL beam to the MC. The PSL-MC axes were mismatched pretty badly according to Suresh anyway, so this had to be done no matter what.
I have completed the new EPICS channel database for the c1psl and c1ioo channels (now combined into the new c1psl Acromag machine). I've tested a small subset of channels on the electronics bench to confirm that the addressing and analog channel calibrations are correct in a general sense. At this point, we are handing the chassis off to Chub to complete the wiring of the Acromag terminals to Dsub feedthroughs. At the 40m meeting today, we identified Feb. 17-22 as a potential window for installation in the interferometer (Gautam is out of town then). Below are some implementaton details for future reference.
For analog input (ai) channels, the Acromag outputs raw values ranging from +/-30,000 counts, but the EPICS IOC interprets the data type as ranging from +/-2^15 = 32,768. Similarly, for analog output (ao) channels, the Acromag expects a drive signal in the range +/-30,000 counts. To achieve proper scaling, Johannes had previously changed the EGUF and EGUL fields from +/-10 V to +/-10.923 V. However, changing the engineering fields makes it much harder for a human to read off the real physical I/O range of the channel.
A better way to achieve the correct scaling is to simply set the field ASLO=1.09225 (65,536 / 60,001) in addition to the normal EGUF and EGUL field values (+/-10 V). Setting this field forces a rescaling of the number of raw counts that works as so (assuming a 16-bit bipolar ADC or DAC, as are the Acromags):
OVAL = (RVAL * ASLO + AOFF + 2^15) * (EGUF - EGUL) / 2^16 + EGUL
In the above mapping, OVAL is the value of the channel in engineering units (e.g., V) and RVAL is its raw value in counts. It is not the case that either the ASLO/AOFF or EGUF/EGUL fields are used, but not both. The ASLO/AOFF parameters are always applied (but their default values are ASLO=1 and AOFF=0, so have no effect unless changed). The EGUF and EGUL parameters are then additionally applied if the field LINR="LINEAR" is set.
This conversion allows the engineering fields to remain unchanged from the real physical range. The ASLO value is the same for both analog input and output channels. I have implemented this on all the new c1psl and c1ioo channels and confirmed it to work using a calibrated input voltage source.
I am working towards redesigning the endtables. I've attached the first version of the layout. As per Steve's comment I've tried to leave a 2" empty space on all sides of the table. It still has to be updated with the whole 40m layout to be more precise about the pickoff and the ingoing beam directions.
1. I wonder how the mode profiling/matching was considered in the new layout.
I can see the distances between the components and lenses are largely different from the old ones.
This is OK if you plan to go through a new mode matching solution with new lenses.
But it takes
a certain amount of time.
Note that we don't care the distance after the last lens as the Rayleigh range there is supposed
to be long enough to allow this kind of change.
2. The huge frustration of the green alignment in the old setup was caused by the 3D beam steering
at the last two 2" mirrors. i.e. the beam elevation on the table does not match with the beam elevation of the cavity.
In order to avoid this, I suggest you to use three 45 deg 2" mirrors instead of two. In fact these mirrors are supposed to be used at 45deg incidence!
3. The incident green beam and the transmitted IR beam should share a same path as they
share a same cavity mode.
This means that you should use a harmonic separator for the transmitted light pick-off.
4. Use the harmonic separator for the fiber path too. Get the mirror spec from Jamie.
5. Since the optical window on the chamber has a wedge angle, the beam paths are not straightforward.
The cavity beams can't be moved as they are constrained by the arm cavity.
Probably there is almost no freedom to move even for the oplev beams.
It would be safe just to follow the old positions and angles on the window.
Make sure the beam on the drawing is realistic. The angles of the oplev beams in the old setup look strange.
Is there a possibility to replace the optical window so that it has an AR for 532 and 1064 at least???
6. I wonder if the rejected beam by the Farady have a realistic angle or not. Check it with the old setup.
It is definitely better to have a steering mirrror and a lens before the refl PD.
7. The IR QPD and trans PD are intended to be used for the low and high power detection.
I forgot which is which. So check the range of them and think about the power distribution.
8. We should have separated CCDs for IR Trans and Green Refl.
We had a terrible ghost green beam on the IR trans CCD.
Thus, think about the amount of ghost reflection and consider filtering if necessary.
Where is IP-ANG ? It is good practice to use two mirrors at launching and detecting the beam, so you can walk it - precisely adjust it.
The window can be replaced at ~$1,500 ea. 10 weeks as optical quality BK7 with dual AR
As a reference. The elog runs on background in nodus.
To kill the process:
1) pkill -3 elogd
2) rm -f /var/run/elogd.pid
To restart it:
elogd -p 8080 -c /export/elog/elog-2.7.5/elogd.cfg -D
When Sanjit and I were looking at the adaptive filtering system on Monday and Friday, we noticed that turning on the Accelerometers (which had been used in the past) seemed to do good things, but that turning on the seismometers (which I just put into the system last week) made the OAF output integrate up. Rana pointed out that this is an indication of a missing high pass filter. And indeed, when I put the seismometers in, I neglected to copy the high pass filter at low frequencies, and the low pass at 64Hz from the accelerometer path to the seismometer path. The accelerometers had a HP at 1Hz, which is okay since they don't really do useful things down to the mHz level. I gave all of the seismometers HP at 1mHz. These are now in the filter banks in the ASS_TOP_PEM screen. The accelerometers are on channels 15, 16, 17, 18, 19, 20 and the seismometers are on channels 2, 3, 4, 10, 11, 12, 24.
I now need to modify the upass script to turn these filters on before doing adaptive filtering.
Valera and I put the 2 Guralps and the Ranger onto the big granite slab and then put the new big yellow foam box on top of it.
There is a problem with the setup. I believe that the lead balls under the slab are not sitting right. We need to cut out the tile so the thing sits directly on some steel inserts.
You can see from the dataviewer trend that the horizontal directions got a lot noisier as soon as we put the things on the slab.
You'll have to ask Steve how deep he cut, but the tile is cut around the lead balls, so they are not sitting on the linoleum. They might just be sitting on the concrete slab, or whatever Steve found underneath the tile, instead of fancy steel inserts, but at least they're not on the tile. I don't know why things got noisier though...