Using instructions from Bram and Suresh, I was able to plug in connectors to BOSEMs. Today I've tested electronics, everything works good. Jamie made an medm screen and channels for TTs. Sliders for pitch and yaw go from -100 to 100 counts. Calibration to angle is 1e-5 rad / count.

TTs are in the clean room waiting for installation.

Please leave here what was the instruction by Bran and Suresh so that the other people can redo it sometime later!

 The connectors can be plugged into the BOSEMs if we loosen the two screws which hold down the mini-D connector and the flex circuit.  Tighten the screws after the connector is pluged in.

[Yoichi, Jenne]

Hooray!!! The Tip Tilts are completely done!  The only things remaining are (1) Install 4 TTs in chambers sometime in September and (2) do shake tests / take TFs of the spare.

Today we balanced and characterized #'s 1 and 5.  All 5 TTs are waiting happily on the flow bench in the cleanroom for installation.

[Jenne, Manasa]

2 colors 2 arms realized!

1. Spot centering:

We spot centered the IR in both arms.
- Use TT1 and TT2 to center in Y arm (I visually center the spots on the ITM and ETM and then use TTs iteratively)
- Use BS-ETM to center in X arm

Spot positions after centering
               X arm            Y arm
         itmx    etmx        itmy    etmy
pitch    -0.86    0.37        1.51    0.05
yaw      0.01    -0.1        0.08    0.10

2. TT1 drifting in pitch (Bistable)
During the arm alignment routine for spot centering, we observed that TRY dropped (from TRY = 0.9 until the arm lost lock) every 40minutes or so. The arm was relocked by moving TT1 in pitch. The (locking - unlocking due to drift - relocking) cycle was monitored and we observed that it was bistable i.e. if TT1 was moved up in pitch (0.2 on the slider) to relock for the first time ; the next time it lost lock, TT1 had to be moved down by nearly the same distance to relock the arm.
Moving TT2 or the testmasses did not help with relocking the arms; so TT1 seems to be the one causing all th trouble atleast for today.

3. ALS - green alignment

We then moved on to Ygreen.  We used the out of vac steering mirrors to center the beam on the 2 irises that are in place on the table, which was a good starting place.  After doing that, and tweaking a small amount to overlap the incident and reflected beams on the green steering mirrors, we saw some mode lock.  We adjusted the end table steering mirrors until the Ygreen locked on TEM00.  We then followed Rana's suggestion of locking the IR to keep the cavity rigid while we optimized the green transmission.  Yuta, while adjusting ITMY and ETMY (rather than the out of vac mirrors) had been able to achieve a green transmission for the Yarm of ~2700 counts using the GTRX DC PD that's on the table. We were only able to get ~2200, with brief flashes up to 2500.

After that, we moved on to the X arm.  Since there are no irises on the table, we used the shutter as a reference, and the ETM optic itself.  Jenne looked through the viewport at the back of the ETM, while Manasa steered mirrors such that we were on the center of the ETM and the shutter.  After some tweaking, we saw some higher order modes lock.  We had a very hard time getting TEM00 to stay locked for more than ~1 second, even if the IR beam was locked.  It looks like we need to translate the beam up in pitch.  The leakage of the locked cavity mode is not overlapped with the incident beam or the promptly reflected beam.  This indicates that we're pretty far from optimally aligned.  Manasa was able to get up to ~2000 counts using the same GTRX PD though (with the Ygreen shutter closed, to avoid confusion).  Tomorrow we will get the Xarm resonating green in the 00 mode.

We need to do a little cleanup on the PSL green setup.  Yuta installed a shutter (I forget which unused one he took, but it was already connected to the computers.), so we can use it to block the PSL green beam.  The idea here is to use the 4th port of the combining beam splitters that are just before each beat PD, and place a PD and camera for each arm.  We already have 2 PDs on the table connected to channels, and one camera, so we're almost there. Jenne will work on this tommorrow during the day, so that we can try to get some beat signals and do some handoffs in the evening.

- I took the shutter from AS table to use it for the PSL green. It was sitting near MC REFL path unused (elog #8259).

- If X green lock is not tight, maybe temporarily increasing loop gain helps. This can be done by increasing the amplitude of the frequency modulation or increasing green refl PD gain. Also, if X green beam spot is too wiggly compared with Y green, it is maybe because of air flow from the air conditioner (elog #6849). I temporarily turned it off when I did X green steering last summer.

- X green transmission on PSL table reached ~270 uW last summer (elog #6849, elog #6914). Y green transmission is now ~240 uW and ~2700 counts at maximum. So, X green transmission should reach ~3000 in counts.

- Did you have to re-align TRX path? We moved the harmonic separator on X end table horizontally to avoid IR TRX clipping before beam centering on X arm (elog #8162). I wonder what is the current situation after the beam centering.

 - We tried locking with the air conditioning switched off at the X-end

- TRX path is unaltered (IR still goes through the center of the harmonic separator.

During the vent we have tried to measure the distances of the optical tables for BS-ITMX and BS-ITMY.
We need to take into account the difference between the AutoCAD drawing and the reality.

X direction distance of the table center for BS and ITMX:
84.086" (= 2135.8mm)
(This is 84.0000" in AutoCAD drawing)

Y direction distance of the table center for BS and ITMX:
83.9685" (= 2132.8mm)
(This is 83.5397" in AutoCAD drawing)

We used two scales attached each other in order to measure the distance of the certain holes on the tables.

We got more numbers that were estimated from several separated measurements.
I think they were not so accurate, but just as a record, I also put the figure as an attachment 2.

I think this table will help us to fix the scanning range of the Marconi frequency. This will also help in predicting the position of the resonance peak corresponding to the injected frequency.

f_diff = f_m ±80 MHz ;                     f_diff = N*FSR_y ;              FSR_y = 3.893 MHz.

Summary:

I have written a code(a basic one which needs a lot of improvements, but still does the job) for taking multiple measurements from the AG4395A. I have also written a separate code for plotting the data taken from the previoius code along with the error bars upto 1 standard deviation.

Details on How To Operate AG4395A:

1. Under 'Measurement' tab, press the 'Meas' button and select the Analyzer Type (Network Analyzer or Spectrum Analyzer).
2. Then under the same options select which 'ratio' needs to be measured (A/R, B/R or A/B).
3. Then press the 'Format' button to select what needs to be measured (Eg - Log|Mag|, Phase, etc.).
4. In order to measure and see two channels at the same time (Eg - Log|Mag| and Phase), press the 'Display' button and select 'Dual Channel'.
5. Using the 'Scale' button we can set the scale/div or use autoscale and also set the attenuator values of the different channels.
6. The 'Bw/Avg' option gives us an averaging option which averages few sets of data to produce the result. In doing this we lose quiet a lot of data and the resulting plot isn't able to give us the information on the statistical errors.
7. This option also allows us to set the 'Intermediate Frequency' Bandwidth. This basically dictates the sampling rate of the Analyzer. The lower the IF bw, the higher is lesser is the noise (due to less uncertainty in Frequency).
8. The 'Cal' button helps us calibrate the Analyzer to the current connections and signals. This is done because there is usually a difference in the 'cable lengths' for the two channels which introduces an extra phase term depnding upon the rf frequency. The calibration can be simply done by removing the Device Under Test (DUT) and diectly connecting the coaxial cables to the channels. After this the 'Calibrate Menu' allows us to calibrate the response using the short, open and thru methods.
9. Now, under the 'Sweep' tab, the 'Sweep' button allows us to select various sweep options such as 'Sweep Time' (Auto, or set a time), 'Number of Points' (b/w 201-801) and 'Sweep Type' (Linear, Log, List Freq. etc.).
10. Using the 'Source' button we can set the source power in dBm units (Usually kept as -20 to -10 dBm).
11. The Scan Range can be set in a few ways such as using the start and end points or using the center and span range/width.
12. After setting up all of the above, we can take the measurement either from the analyzer itself or using one of the control PCs. The command to download the data from AG4395A is netgpibdata -i 192.168.113.105 -d AG4395A -a 10 -f [filename].

Brief Details on How the 'AGmeasure' command works:

AGmeasure is a python script developed by some of the people who work at 40m. It is set as a global command and can be used from within any directory. The source code is in the scripts folder on the network, or else it can also be found in Eric Quintero's git repository. This command accepts at the very least a parameter file. This is supposed to be a .yml file. A template (TFAG4395Atemplate.yml) can be found in the scripts folder or in Eric's repo. There are some other options that can be passed to this command, see the help for more details.

The Multi_Measurement Script:

This script calls the 'AGmeasure' command repetitively and keeps storing the data files in a folder. Right now, the script needs to be fed in th template file manually at prompt.

The Test_Plotting Script:

This script plots the a set of data files obtained from the above mentioned script and produces a plot along with the errors bands upto 1 standard deviation of the data. The format (names) and total number of text files need to be explicitly known, for now at least.

Attachments:​

1. The output test files and the two scripts.
2. This is the 'Bode Plot' for a data set made using the above two scripts.

To Do:

• Improve upon the two scripts to be as compatible as the AGmeasure function itself.
• Try and incorporate the whole script into AGmeasure itself along with improving upon the templates.
• The above details, with some edits perhaps, can go into the 40m wiki too(?).

Update: Increased the font size in the plot. Added a few comments to the two scripts

To Do: Need to consider the transfer function as a single physical quantity (both the magnitude and phase) and then take the averages and calculate the standard deviation and then plot these results. 

EDIT:

The attachment with the test files and the code now also contains a pdf with all the relations/equations I have used to calculate the averages and errors.

I copied the netgpibdata folder onto rossa (under the directory ~/Agilent/), which contains all the necessary scripts and templates you'll need to remotely set up, run, and download the results of measurements taken on the AG4395A network analyzer. The computer will communicate with the network analyzer through the GPIB device (plugged into the back of the Agilent, and whose communication protocol is found in the AG4395A.py file in the directory ~/Agilent/netgpibdata/).

The parameter template file you'll be concerned with is TFAG4395Atemplate.yml (again, under ~/Agilent/netgpibdata/), which you can edit to fit your measurement needs. (The parameters you can change are all helpfully commented, so it's pretty straightforward to use! Note: this template file should remain in the same directory as AGmeasure, which is the executable python script you'll be using). Then, to actually set up, run, and download your measurement, you'll want to navigate to the ~/Agilent/netgpibdata/ directory, where you can run on the command line the following: python AGmeasure TFAG4395Atemplate.yml

The above command will run the measurement defined in your template file and then save a .txt file of your measured data points to the directory specified in your parameters. If you set up the template file such that the data is also plotted and saved after the measurement, a .pdf of the plot will be saved along with your .txt file.

Now if you want to just download the data currently on the instrument display, you can run: python AGmeasure -i 192.168.113.105 -a 10 --getdata

Those are the big points, but you can also run python AGmeasure --help to learn about all the other functions of AGmeasure (alternatively, you can read through the actual python script).

Happy remote measuring! :)

I've modified the lsc.mdl and lsp.mdl files back to an older configuration, where we do not use an IO processor.  This seems to let things work for the time being on megatron while I try to figure out what the is wrong with the "correct" setup which includes the IO processor.

Basically I removed the adcSlave = 1 line in the cdsParameters block.

I've attached a screen shot of the desktop showing one filter bank in the LSP model passing its output correctly to a filter block in the LSC.  I also put in a quick test filter (an integrator) and you can see it got to 80 before I turned off the offset.

So far this is only running on megatron, not the new machine in the new Y end.

The models being use for this are located in /cvs/cds/caltech/cds/advLigoRTS/src/epics/simLink

Took finer measurements of the x-arm aux laser actuator tranfer function (10 kHz - 1 MHz, 1024 pts/decade) using the Moku.

--------------------------------------

I took finer measurements using the moku by splitting the measurement into 4 sections (10 - 32 (~10^4.5) kHz, 32 - 100 kHz, 100 - 320 kHz, 320 - 1000 kHz) and then grouping them together. I took 25 measurements of each ( + a bonus in case my counting was off), plotted them in the attached notebook, and calculated/plotted the standard deviation of the magnitude (normalized for DC offset). Could not upload to the ELOG as .pdf, but the pdf's are in the .zip file.

--------------------------------------

Next steps are to do the same stdev calculation for phase, which shouldn't take long, and to use the vectfit of this better data to create a PZT inversion filter.

After finishing my last elog entry, I monitored the digital loop's error signal (the control signal for the fast loop) and the output to the laser heater remotely, (from West Bridge), using dataviewer. The ref cav surrounding can temperature was set to 36 degrees C.

With the loop closed and a gain of 0.008, after seeing the output voltage to the laser heater (TMP_OUTPUT) remain fairly constant and the error signal (TMP_INMON) stay close to zero for ~3 hours, I tried to step the temperature. (This was at 2am last night). I was working remotely from West Bridge. To step the temperature I used the following command:

ezcawrite C1:PSL-FSS_RCPID_SETPOINT 35.5

Rather than change the can temperature to 35.5 C, it outputted:

C1:PSL-FSS_RCPID_SETPOINT=0.

It had set the setpoint to 0 degrees C, which was essentially turning the heater off. I tried resetting it back to 36 and had no luck. I tried changing the syntax slightly.: ezcawrite C1:PSL-FSS_RCPID_SETPOINT=36 and ezcawrite C1:PSL-FSS_RCPID_SETPOINT (36). No success.

I ran over to the 40m and changed the temperature back to 36 manually. The in-loop temp sensor had decreased to 31.5 degrees C before I was able to step the setpoint back up. The system seems to have recovered from this large impulse though, and the laser has remained locked.

(5 hours of minute-trend data)

From left to right: 

Top: Out-of-loop can temp sensor; Voltage sent to heat can

Middle: signal sent to heat the laser (TMP_OUTPUT); room temp

Bottom: Error signal for slow loop (sampled control signal from fast loop); In-loop can temp sensor

At 9:30 this morning (7 and a half hours after accidentally setting the setpoint to zero), I came in to the 40m. TMP_OUTPUT was still decreasing but was slowing somewhat, so I decided to step the can temperature up half a decree to 36.5 C.

TMP_OUTPUT responded to the step, but it is also oscillating slowly with room-temperature changes, and these oscillations are on the same order as the step response. The oscillations look like the room-temp oscilations, but inverted. (TMP_OUTPUT reaches maxima when RMTEMP reaches minima). Oddly, there does not appear to be much of a time delay between the room temperature and TMP_OUTPUT signals. I would expect a time delay since there's a time constant for a room-temperature change to propagate into the cavity. Perhaps the laser itself is susceptible to room-temperature changes and those propagate into the laser cavity on a much faster time scale. I don't know the thermal coupling of ambient temperature changes into the laser.

(24-hours of second-trend data)

Options are:

--If the system can handle it, do a larger temperature step (3 degrees, say), so that I can more clearly distinguish the oscillations with room temp from the step response.

--Insulate the cavity with foam (will in principle make the temperature over the can surrounding the ref cav more uniform and less affected by room temperature changes).

--Insulate the laser? Is this possible?

--Leave the system as is and, as a first approximation, fit the room-temp data to a sine wave and subtract it off somehow from my data to just see the step response.

--Don't bother with steps and just try to get the transfer function from out-of-loop temperature (RCTEMP, which is affected by temperature noise from the room) to TMP_OUTPUT via taking the Fourier transforms of both signals.

I'm flying out tomorrow morning, so I'll either need to figure out how to step the temperature set point of the can remotely, successfully, or I'll need someone to manually enter in the temperature steps for me in the control room.

[Jenne Kiwamu Joe Osamu Steve Koji]

Yesterday (21st), we closed the BSC and the four testmass chambers.

We splitted the team into three.

- Wiping team (Jenne/Kiwamu)
- Suspension team (Osamu/Koji)
- Door closing team (Joe/Steve)

While the wiping team was working, the suspension team prepared the next suspension.
Once the mirror was wiped, the suspension team restored that suspension at the position of the markings on the table.

After the wipe of the first mirror, the wiping team got experienced and they were the fastest among the teams.
So the wiping team worked as the second suspension team when necessary.

All of us became the closing team after the last suspension has been restored.

We checked that we still have the Michelson fringes and the oplev pointings.

In total, the work was very efficient such that we only took four hours for the entire process.

We left the suspension marking on the optical tables because they are quite useful.

[Steve, Bob, Joe, Zach, Alberto, Kiwamu, Koji]

We opened the OMC-IMC access connector, ITMX North door, and ITMY West door.
We worked from 9:30-11:00.
The work was quite smooth thanks to the nice preparation of Steve as usual.

Thank the team for the great work!

[Gautam/Chub/Koji] ~ Mini discussion

Maintenance / Upgrade Items

(Priority high to low)

• TT/IO suspension upgrade (solidworks work) -> order components -> TT characterization
• Acromag upgrade c1susaux
  • Produce spread sheetfor DB files. Learn new format of the DB file with Acromag. Develop a python code for the DB file generation (Jon->Koji)
• Satellite Box upgrade
  • Rack mount? Front panel DB connectors. New circuits (PD-LED)
     
• Acromag iscaux1/2 & isc whitening upgrade
   
• new RC mirror characterization -> installation

I have acquired 5 pieces of the Teledyne AP1053 from Koji - these are now at the 40m. I will determine an appropriate location for storage of these and update. We are also looking to acquire 5 more of these. The combination of high power output (26dBm), low gain (10dB), and low noise figure (1.5dB) are quite uncommon in an amplifier and so these should be used only when such properties are required simultaneously.

*Steve informs me that these amps have been stored in the RF cabinet E6 along the east arm.

Steve's note: Teledyne rf amp product selection guide

                   Teledyne rf low noise amp guide

Teledyne AP1053 etc were transported from Rich's office to the 40m. The box is placed on the shelf at the entrance.

My record tells that there are 7 AP1053 in the box. I did not check the number this time.

 This is the fone storree 

we should turn off 3977,3979 and 2351 has no function

Edit, JD:  x8925 is at the Visitor desk, and isn't on the map.

[Kruthi, Milind]

Yesterday, we were able to capture some images of objects at a distane of approx 60cm (see the attachment), with the GigE mounted onto the telescope. I think, Johannes had used it earlier to image the ETMX (https://nodus.ligo.caltech.edu:8081/40m/13375). His elog entry doesn't say anything about the focal length of the lenses that he had used. The link to the python code he had used to calculate the lens solution wasn't working. After Gautam fixed it, I took a look at it. He has used 150mm (front lens) and 250mm (back lens) as the focal length of lenses for the calculation. Using the lens formula and an image of a nearby light source, with a very rough measurement, I found the focal lengths to be around 14 cm and 23 cm. So, I'm assuming that the lenses in the telescope are of same focal lengths as in his code, i.e 150mm and 250mm.

no BMP files 

With the objective of designing a telescope system for the Gig-E, a system of two lenses is implemented. A rough schematic of the telescope system is attached. Variables in the system include the focal lengths of the two spherical lenses(f1, f2), distance between the lenses(t), distance between the test mass and the lens combination(u), distance between the other lens and the sensor(v). Also the size of the object to be desired ranges from 3’’ which is the size of the test mass to 1’’ which is approximately focusing on the beam spot implying that the required magnification ranges from 0.06089 to 0.1826 (since the sensor image circle size if ¼”)
The lenses are selected to be 2” in diameter so as to ensure sufficient collected power.

Going through the focal lengths available, namely 50, 100, 150, 200, 250 mm, and noting that the object distance would be within the ranges of 1500 to 2500 mm, plots of various accessible u and v for different values of t were obtained. This optimization was done to ensure the proper selection of the lenses. Additionally, a sensitivity analysis was performed and plots depicting the dependence of magnification on the precision limiting measurements of u (1 mm) and t (5 mm) were obtained. (These were scatter plots quantifying the deviation from the desired magnification ranges). The plots depict the error term induced on the magnification if there was an error in measuring the distance between the lenses as 5mm and if the precision in measuring the object to lens distance by 1mm.

The telescope design might be limited by spherical aberrations and coma, which might be resolved by either using aspherical lenses or by increasing the f-number (typically with an f number around 5 or 6). The use of aspherical lenses particularly parabolic lenses was considered, however this was found to be quite an expensive route. 

Analyzing the plots and taking into consideration the restrictions of the slotted lens tubes, the precision in measurement of the distances, a 150 mm- 250mm focal length solution is proposed. With a diameter of 2”, the f number is computed to be 2.95 and 4.92. With this combination and the object distances lying between 1500 to 2500 mm, the image distance to the sensor varies between 51 to 100mm. So a slotted lens tube controlling the distance between the lenses would be required.

I also considered a combination of focal lengths 250mm and 250mm, as then both of the lenses would at least have an f number of 4.92. The results for this combination are also attached. The image distance from the lens combination is about a 100 to a 140 mm. However, this would require much longer slotted length tubes thereby adding to the cost of the system. The number of accessible u-v points is the same as that for the 150-250 combination. 

I am still trying to search for a much more concrete way of quantifying aberrations.

 I used a la mode to make a design for the coupling telescope with a 3.3um target waist, that included the collimator in the overall design. The plot is below, and code is attached.

The components are as follows:

 label         z (m)     type    parameters         

   -----         -----     ----    ----------         

    lens1         0.7681    lens    focalLength: 0.5000

    lens2         0.8588    lens    focalLength: 0.0350

    collimator    0.8832    lens    focalLength: 0.0020

The z coordinates are as measured from the beam waist of the NPRO (the figure on the far left  of the plot).

Moving forward, this setup will be used to couple the NPRO (more specifically, the AUX lasers) light into the SM 980 fibers, as well as to help characterize the fibers themselves.

Ultimately, this will be a key component in the Frequency Offset Locking project that Akhil and I are working on, as it will transport the AUX light to the PSL, where the two beams will be beaten with each other to generate the input signal to the PID control loop, which will actuate the temperature servos of the AUX lasers.

Aim: To find telescopic lens solution to image test mass onto the sensor of GigE camera.

I wrote a python code to find an appropriate combination of lenses to focus the optic onto the camera keeping in mind practical constraints like distance of GigE camera from the optic ~ 1m and distance between the lenses need to be in accordance with the Thorlab lens tubes available. We have to image both the enire optic of size 3" and beam spot of 1" using this combination of lens. The image size that efficiently utilizes the entire sensor array is 1/4". Therefore the magnification required for imaging the entire optic is 1/12 and that for the beam spot is 1/4.

I checked the website of Thorlabs to get the available focal lengths of 2" lenses (instead of 1" lenses to collect sufficient power). I have tried several combination of lenses and the ones I found close enough to what is required have been listed below along with thier colorbar plots.

a) 150mm-150mm (Attachment 2 & 3)

With this combination, object distance varies like 50cm for 1" beam spot to 105cm for 3" spot. Therefore, it posses a difficulty that there is a difference of ~48cm in the distances between the optic and camera in the two cases: imaging the entire optic and the beam spot.

b) 125mm-150mm (Attachment 4 & 5)

With this combination, object distance varies like 45cm for 1" beam spot to 95cm for 3" spot. There is a difference of ~43cm in the distances between the optic and camera in the two cases: imaging the entire optic and the beam spot.

c) 125mm-125mm (Attachment 6 & 7)

The object distance varies like 45cm for 1" beam spot to 90cm for 3" spot. There is a difference of ~39cm in the distances between the optic and camera in the two cases: imaging the entire optic and the beam spot.

Sensitivity check was also done for these combination of lenses. An error of 1cm in object distance and 5mm in the distance between the lenses gives an error in magnification <2%.

The schematic of the telescopic lens system has been given in Attachment 8.

[Yuta, Jenne]

In an effort to see what is going on with the beam spot motion, and to investigate whether or not it might be caused by passive TT motion, Yuta and I installed some oplev mirrors in-vac, to make a PR2 oplev.

Yuta did not move either of the in-vac oplev mirrors that are for ITMX.  Instead, he took the incident red beam as it was, and put a spare in-vac oplev mirror there.  Then he used another spare oplev mirror to get the beam out, and on to the one out-of-vac steering mirror before the QPD.  I then steered the out of vac mirror to center the beam on the QPD.

This means (1) that ITMX cannot have an oplev right now, although the HeNe was off anyway, and (2) that as soon as we take these spare oplev mirrors out, we should immediately have ITMX oplev back (may need to steer out of vac mirror to get beam onto QPD).

Yuta is currently taking measurements to see if PR2 motion has high coherence with the intracavity motion.