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ID Date Author Type Category Subject
8403   Wed Apr 3 16:03:59 2013 ChloeUpdate QPD Voltage Regulators

The voltage regulator on the QPD breadboard seems to be having problems... yesterday Eric helped me debug my circuit and discovered that the +12V regulator was overheating, so we replaced it. Today, I found that the -12V regulator was also doing the same thing, so I replaced it. However, it's still overheating. We checked all of the setup for the power regulators yesterday, so I'm not sure what's wrong.

I've also noticed that not all the connections on the breadboard that I've been using seem to work - I may search for a new breadboard in this case. Need to check I'm not doing something stupid with that.

8406   Wed Apr 3 18:27:03 2013 KojiUpdate QPD Voltage Regulators

Breadboards may not be suitable for a reliable work. Why don't you switch to any protoboard and real soldering?

8478   Tue Apr 23 16:31:13 2013 EricConfiguration PD frequency response

[Eric, Riju]

Summary: Routing Fibers on AP table for Photo Diode Frequency Response Measurement System

Objective: We are to set-up one simultaneous transfer-function measurement system for all the RF-PDs present in 40m lab. A diode laser output is to be divided by 1x16 fiber splitter and to be sent to all the PDs through single-mode fiber. The transfer function of the PDs will be measured using network analyzer. The output of the PDs will be fed to network analyzer via one RF-switch.

Work Done So Far: We routed the fibers on AP table. Fibers from RF PDS - namely  MC REFL PD, AS55, REFL11, REFL33, REFL55, REFL165, have been connected to the 1x16 fiber splitter. All the cables are lying on the table now, so they are not blocking any beam.

We will soon upload the schematic diagram of the set up.

Missing Component: Digital Fiber Power Meter, Thorlab PM20C

8484   Wed Apr 24 14:24:40 2013 RijuUpdate PD frequency response

Here I am attaching the first schematic diagram of the PD frequency response set-up, I will keep updating it with relevant informations with the progress of the work.

Description: Our objective is to set-up one simultaneous transfer-function measurement system for all the RF-PDs present in 40m lab. A diode laser will be used to illuminate the PDs. The diode laser output will be divided by 1x16 fiber splitter and will be sent to all the PDs through single-mode fiber. The transfer function of the PDs will be measured using network analyzer(Agilent 4395A). The output of the PDs will be fed to network analyzer via one RF-switch. The diode laser will be controlled by the controller ILX LDC 3744C. The scanning frequency signal will be fed to this controller from network analyzer through its external modulation port. The output of the controller will be splitted  into two parts: one will go to laser diode and the other will be used as reference signal for network analyzer.

Attachment 1: PD_freq_resp.pdf
8492   Thu Apr 25 17:56:28 2013 RijuConfiguration PD frequency response

[Eric, Riju]

Today we have routed the fibers from 1x16 fiber splitter to POX table for POX11 PD and POP55 PD. Also we labeled the fibers on AP table, they have been fixed on the table. The photo of the table after work is attached here. We will do it for POX table tomorrow.

Attachment 1: IMG_0495.JPG
8493   Thu Apr 25 18:58:06 2013 KojiConfiguration PD frequency response

No.... what I told was to put the roll next to the splitter, not on the table.
The table area is more precious than the rack space.

Koji> The slack of the fibers should be nicely rolled and put together at the splitter side.

8497   Fri Apr 26 17:08:42 2013 RijuConfiguration PD frequency response

 Quote: No.... what I told was to put the roll next to the splitter, not on the table. The table area is more precious than the rack space. Koji> The slack of the fibers should be nicely rolled and put together at the splitter side.

Ok, will do it on the coming week.

8511   Tue Apr 30 12:25:23 2013 ChloeUpdate QPD

Annalisa and I met yesterday and fixed the voltage regulator on the breadboard so the QPD circuit is working. We will meet with Eric on Thursday to determine the course of action with measurements.

8532   Tue May 7 03:08:12 2013 JenneUpdate PRM yaw responsible for RIN

Koji spent some time earlier this evening exploring where the excess RIN that we see in the PRC is coming from.

He did this by locking the PRMI (MICH on AS55Q, PRCL on REFL33I, Pnorm for MICH = sqrt(POP110) with 0.1, Pnorm for PRCL = sqrt(POP110) with 10, MICH gain = -30, PRCL gain = 8), and then exciting each relevant optic, one at a time, in yaw.  The excitation was always using the ASCYAW excitation point on each of the optics (BS, PRM, ITMX, ITMY), with a frequency of 4.56 Hz, and an amplitude of 30 counts.

He also took reference traces with no optics excited.

Here, I plot (for each excited optic separately) the reference traces and traces during excitation for POP110_I_ERR, POPDC, and the OPLEV_YERROR for the optic that is being excited.

What we are looking for (only in yaw, since we see on the cameras that the dominant motion is in yaw) is an increase in POPDC and POP110 at the same frequency as an optic's excitation.

We see that neither ITM is contributing a noticeable amount to either POPDC or POP110.  BS is contributing a little bit, but PRM is clearly contributingNo this entry should be read. (KA)

A week or two ago, I calculated in elog 8489 that the angular motion that we see does not explain the RIN that we're seeing, unless our cavity is much more unstable than Jamie calculated in elog 8316

I think that I need to install one of the T240's on the new granite slab, and see what kind of coherence we have between seismic and PRM yaw motion, and if FF can get rid of it.

8604   Tue May 21 14:50:52 2013 Max HortonUpdate Importing New Code

There was an issue with running the new summary pages, because laldetchar was not included (the website I used for instructions doesn't mention that it is needed for the summary pages).  I figured out how to include it with help from Duncan.  There appear to be other needed dependencies, though.  I have emailed Duncan to ask how these are imported into the code base.  I am making a list of all the packages / dependencies that I needed that weren't included on the website, so this will be easier if/when it has to be done again.

8678   Wed Jun 5 14:39:41 2013 Max HortonUpdate Importing New Code

Most dependencies are met.  The next issue is that matplotlib.basemap is not installed, because it is not available for our version of python.  We need to update python on megatron to fix this.

8762   Thu Jun 27 05:44:51 2013 ranaUpdate 40MARS wireless network problems

 Quote: I'm not sure what's going on today but we're seeing ~80% packet loss on the 40MARS wireless network.  This is obviously causing big problems for all of our wirelessly connected machines.  The wired network seems to be fine. I've tried power cycling the wireless router but it didn't seem to help.  Not sure what's going on, or how it got this way.  Investigating...

I'm still seeing some problems with this - some laptops are losing and not recovering any connection. What's to be done next? New router?

8782   Fri Jun 28 11:33:32 2013 SteveUpdate 40MARS wireless network problem

 Quote: I'm not sure what's going on today but we're seeing ~80% packet loss on the 40MARS wireless network.  This is obviously causing big problems for all of our wirelessly connected machines.  The wired network seems to be fine. I've tried power cycling the wireless router but it didn't seem to help.  Not sure what's going on, or how it got this way.  Investigating...

Mike and Christian brought over a Mac laptop for surf Alex.

They power cycled the wireless router of 40Marsh and labtops are working.  Seeing 75-80% signals on all 3 Dell lab top sisters at both end of the lab

8795   Wed Jul 3 11:07:17 2013 AlexSummary Photodetector Characterization

[Alex, Koji]

We characterized Koji's BBPD MOD for REFL165 (see attachment).

First, we calibrated the Agilent 4395 Network Analyzer (NA) to account for differences in cable features between the Ref PD and Test PD connections. This was done using the 'Cal' softkey on the NA.

Then we performed transimpedance measurements for the test PD and reference PD relative to the RF output of the NA and relative to each other (see 2nd attachment. Note that the NA's RF output is split and sent to both the IR Laser and the NA's Ref input).

Next, we made DC measurements of the outputs of the photodetectors to estimate the photocurrent distribution of the transimpedance setup (like the 2nd attachment, but with the outputs of the PDs going to a multimeter). By photocurrent distribution, we mean how the beamsplitter and respective quantum efficiencies/generalized impedance/etc. of the PDs influence how much current flows through each PD at with a DC input.

Finally, we measured the output noise as a function of photocurrent (like the 2nd attachment, but with a lightbulb instead of the IR Laser). Input voltages for the lightbulb ranged from 0mV to 6V. Data was downloaded from the NA using netgpibdata from the scripts directory. Analysis is currently in progress; graphs to come soon.

Attachment 1: BBPD_PCB.pdf
Attachment 2: transimpedance_measurement.pdf
8806   Mon Jul 8 16:27:49 2013 AlexUpdate Planned rack additions

Alex and Eric

For the photodetector frequency response automation project, we plan to add modules to rack 1y1 as shown in the attached picture (Note: boxes are approximately to scale).

The RF switch will choose which photodetector's output is sent to the Agilent 4395A Network Analyzer.

The Diode Laser Module is powered by Laser Power Supply, will be modulated by the Network Analyzer and will be output to a 1x16 optical splitter which is already mounted in another rack (not pictured).

The Transformer Module has not been built yet.

We would like to install the power supply and the laser module tomorrow and will not begin routing fibers and cables until we post a drawing in the elog.

Also, our reference photoreceiver arrived today.

Attachment 1: Annotated_Rack_1y1.pdf
8829   Thu Jul 11 12:00:50 2013 AlexUpdate Planned rack additions

[Eric, Alex]

We mounted our Laser Module and Laser Power Source in rack 1y1. We plan to add our RF Switch and Transformer Module to the rack, as pictured. (Note: drawn-in boxes in picture are approximately to scale.) Note that the panel of knobs which the gray boxes overlap is obsolete and will soon be removed.

Attachment 1: Annotated_Rack_1y1_-_update.pdf
8832   Thu Jul 11 23:50:57 2013 gautamConfiguration PZT Driver Board-changes made

Summary:

Continued with tests on the PZT driver board. I made a few changes to replace defective components and also to modify the gain of the HV amplifier stage. I believe the board has been verified to be satisfactory, and is now ready for a piezo to be connected, tested and calibrated.

• I tested the board with the full 100V bias voltage today, working my way up from 30V in steps of about 20V and verifying the output at each stage.
• In order to deliver 100V to the board, it was necessary to change the maximum current limit on the KEPCO supply, which is set at default at ~1.6 mA. The KEPCO power supply placed near rack 1X2 (which I believe was used to power a piezo driver board) is labelled 150V, 12 mA, though I found that the board only drew 7mA of current when the power supply output 100V. I have set the limit to 10 mA for the time being.
• The potentiometer in the third stage (R44 in the schematic) was faulty so I replaced it with another 100K potentiometer, which was verified to work satisfactorily.
• We expect the DAC output to supply a voltage to the input of the PZT driver board in the range -10V to 10V. Today, I verified this by using my temporary break-out cable. I hooked this up to the DAC at 1Y4 and output a 3 Hz sine wave with amplitude of 32000 counts (the maximum) on channel 9. The output as observed on an oscilloscope (image attached) was a 10Vpp sinusoid, confirming the above hypothesis. As mentioned in my previous elog, the gain of the high-voltage amplifier stage is ~15, which would mean the output would saturate if the input were to be >6V. I have changed the gain of all 4 stages (M1-pitch, M1-yaw, M2-pitch and M2-yaw) to ~4.85 by swapping the 158k resistors (R43, R44, R69 and R70 in the schematic) for 51k resistors.
• It was necessary to change the value of the biasing potentiometers after the change in gain so that 0 input voltage once again provided 50V at the output, as required by the PZTs for there to be no tilt. This was done and verified. This biasing voltage now is ~10.4V in all four stages.
• Having adjusted the gain, I tested the circuit over the expected full range of the input voltage from the DAC (from -10V to 10V) from the DS345 function generator (0.05Hz sinusoid). I monitored the output using a multimeter, as the monitor channels were peaking at ~7V, which was above the limit for the oscilloscope I was using. It was verified for all four channels that the output was between 0 V and 100 V (the safe range quoted in the datasheet for the tip-tilts, for this range of input voltages. So I think we are ready to connect a PZT to the board and conduct further tests, and calibrate the PZT.

Pending Issues:

• Koji pointed out that there has to be an anti-imaging filter stage between the DAC output and the filter stage, which I had not considered till this point.Another subtle point is that the DAC output is differential while the driver boards have a single-ended input, which means we effectively lose half the range of the PZTs.
• A suitable candidate is the D000186-rev D. Some information about the present state of this board is detailed in this elog. This board also solves the problem of the differential vs single input as the input to the AI board is differential while the output is single-ended. Koji has given me one of the boards he had collected.
• Some changes will have to be made to this version of the board in order to make it compatible with the existing DAC. I will first have to measure the power spectrum of the DAC output to verify that the AI boards need notches at 64k and 128k. The existing notches are at 16k and 32k, and once the DAC power spectrum has been verified, I hope to affect the necessary changes by switching out the appropriate capacitors on the existing board.
• The AI board is an extra element which I have now added to an updated wiring diagram, attached.

Revised Wiring Diagram:

DAC Max. Output Trace on Oscilloscope

8850   Mon Jul 15 16:51:37 2013 AlexConfiguration Planned AS Table addition

[Eric, Alex]

We are planning to add our reference PD to the southern third of the AS Table as pictured in the attachment. The power supply will go under the table.

8855   Tue Jul 16 10:16:23 2013 KojiUpdate Beatbox XARM whitening modified

The X arm whitening filters of the beatbox were modified.
Now we have about 10 times better floor level above 100Hz and ~3 better at 1Hz.

- The previous whitening was zero@1Hz, pole@10Hz, and the DC gain of the unity.
When the Marconi signal (~30MHz -25dBm) was given to the beatbox (via ZFL-1000LN),
the DC output of the beatbox was only 140mV (lame). This corresponded to 220 counts in
the CDS.
(BTW the signals were calibrated by giving frequency deviation of 1kHz is applied at 125Hz.)

- If you compare the analog measurement of the beatbox output and what we see in the I phase signal,
you can see that we were completely dominated by the ADC noise (attachment 2, blue and red).

- The new whitening is zero@5.2Hz, pole@159Hz, and the DC gain of 10.

- This improved the sensing noise by a factor of ten above 100Hz.

- We are stil llimited by the digitizing noise between 3Hz to 100Hz.
We need steeper whitening like 2nd order from 1Hz to 100Hz. (and probably at DC too).
Now the DC amplitude is about 1.4V (and 2200 counts in the CDS).
So, it is interesting to see how the sensing limit changes by increasing
the overall gain by a factor of 3, and have (zeros@1Hz & poles@10Hz)^2.

This can be implemented on a proto-daughter board.

- By the way, the performance below 2Hz is now better than the analog one with the previous whitening.
This improvement might have come from the replacement of the thick film resistors by thin-film resistors.
(See the circuit diagram)

About the nominal power of the beatbox input.

- Marconi (-20dBm 30MHz) was directly connected to the beatbox. The RF output of -15dBm was observed at the delayline output.
- According to the beatbox schematic, the mixer LO and RF inputs were expected to be -9dBm and -19dBm.
- The nominal mixer LO level is supposed to be 7dBm. Therefore the nominal beatbox input should be -4dBm.

- Assuming 23dB gain of the preamp, the PD output is expected to be -27dBm.

- When the PD out is -27dBm, the RF mon is expected to be -5dBm. This is the level of the RF power expected to be seen in the control room.

- The output of the beatbox was measured as the function of the input to the preamp (before the beatbox input).
With the nominal gain, we should have observed amplitude of ~170. And it is now 1700 because of the whitening modification.

Attachment 1: Beatbox_mod.pdf
Attachment 2: ALS_whitening.pdf
Attachment 3: Beatbox_input_dependence.pdf
9368   Tue Nov 12 21:50:01 2013 ranaUpdate zita network configured

I installed 'nfs-client' on zita (the StripTool terminal). It now has mounted all the shared disks, but still can't do StripTool since its a 32-bit machine and our StripTool is 64.

10657   Fri Oct 31 11:46:15 2014 manasaUpdate Rattling HEPA : Eventually stops

The PSL HEPA stopped working while it was running at 80%. I have closed the PSL enclosure.

Steve is working to fix this.

11392   Tue Jul 7 17:22:16 2015 JessicaSummary Time Delay in ALS Cables

I measured the transfer functions in the delay line cables, and then calculated the time delay from that.

The first cable had a time delay of 1272 ns and the second had a time delay of 1264 ns.

Below are the plots I created to calculate this. There does seem to be a pattern in the residual plots however, which was not expected.

The R-Square parameter was very close to 1 for both fits, indicating that the fit was good.

Attachment 1: cableA_fit.jpg
Attachment 2: cableA_resid.jpg
Attachment 3: cableB_fit.jpg
Attachment 4: cableB_resid.jpg
12352   Fri Jul 29 03:44:04 2016 AakashSummary About Acromag | SURF 2016

I tried to recompile the modbusApp binary for linux-arm acrhitecture since I suspected someting wrong with it. But still the problem persists; I can connect to acromag but cannot access the channels. I have also reconfigured new acromag bus works terminal XT 1221-000 and I want to test if I could access its channels. My target is to complete this acromag setup work before sunday morning so that I can focus towards having some useful results for my presentation.

12825   Mon Feb 13 17:19:41 2017 yinziConfiguration configuring ethernet for raspberry pi

Gautam and I were able to get the Raspberry Pi up and running today, including being able to ssh into it from the control room.

Below are some details about the setup/procedure that might be helpful to anyone trying to establish Ethernet connection for a new RPi, or a new operating system/SD card.

Here is the physical setup:

The changes that need to be made for a new Raspbian OS in order to communicate with it over ssh are as follows, with links to tutorials on how to do them:

3. Enable ssh server: http://www.instructables.com/id/Use-ssh-to-talk-with-your-Raspberry-Pi/

The specific addresses for the RPi we set up today are:

Gateway/Routers/Domain Name Servers: 192.168.113.2

GV: I looked through /etc/var/bind/martian.hosts on chiara and decided to recycle the IP address for Domenica.martian as no RPis are plugged in right now... I'm also removing some of the attachments that seem to have been uploaded multiple times.

12949   Fri Apr 21 13:59:47 2017 Eric GustafsonSummary 1064 nm Semiconductor Laser Fiber Distribution System and Mirror Tomography

1064 nm Semiconductor Laser Fiber Distribution System and Mirror Tomography

Below threshold these Semiconductor Fabry-Perot lasers have an axial mode structure with a spacing of about a THz. As you turn up the current to above threshold the first mode to oscillate saturates the gain down on all the modes and only it oscillates.  The laser I have here in my office (a backup for the one you have at the 40 meter) has a wavelength of 1064.9 nm at 70 Degrees C.  We should be able to temperature tune it down to 1064.3 nm although this could be a bit tedious the first time we do it. The specifications claim a "spectrum width" of 1.097 nm which I believe is the temperature tuning range.  I don’t know what the line width is but it will be single frequency and we shouldn’t have mode hoping problems.  So we should be able to use it in the “Mirror Tomography” experiment.  You might want to use some sort of polarization diversity to avoid the problems of fiber polarization drift.

There have been 2 student projects on using the fiber distributed PD frequency response at1064 nm laser.

“Automated Photodiode Frequency Response Measurement System,” Alexander Cole - T1300618

“Final Report: Automated Photodiode Frequency Response Measurement System for Caltech 40m lab,” Nichin Sreekantaswamy - P140021

I’ll look up a few more references and add include them in the next elog.

Eric

13686   Mon Mar 19 07:37:00 2018 Angelina PanSummary Proposed QPD Optical Arrangement

I am currently working on an optical arrangement consisting of a QPD that measures the fluctuations of an incoming HeNe laser beam that is reflected by a mirror. The goal is to add a second QPD to the optical arrangement to form a linear combination that effectively cancels out the (angular) fluctuations from the laser beam itself so that we can only focus on the fluctuations produced by the mirror.

In order to solve this problem, I have written a program for calculating the different contributions of the fluctuations of the HeNe laser and fluctuations from the mirror, for each QPD (program script attached). The goal of the program is to find the optimal combination of L0, L1, L2, and f2 that cancels the fluctuations from the laser beam (while retaining  solely the fluctuations from the mirror) when adding the fluctuations of QPD 1 and QPD 2 together.

By running this program for different combinations of distances and focal lengths, I have found that the following values should work to cancel out the effects of the oscillations from the HeNe laser beam (assuming a focal length of 0.2 m for the lens in front of the original QPD):

• L0 = 1.0000 m (distance from laser tube to mirror)
• L1 = 0.8510 m (distance from mirror to lens in front of QPD 1)
• L2 = 0.9319 m (distance from beamsplitter to lens in front of QPD 2)
• f2 = 0.3011 m (focal length of lens in front of QPD 2)

Based on these calculations, I propose to try the following lens for QPD 2:

1’’ UV Fused Silica Plano-Convex Lens, AR-Coated: 350 - 700 nm (focal length 0.3011 m). https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=6508

Attachment 1: angelinaCode.py.tar.bz2
13699   Thu Mar 22 17:47:16 2018 Angelina PanSummary Proposed QPD Optical Arrangement
Attachment 1: IMG_0869.jpg
13915   Mon Jun 4 19:41:01 2018 keerthanaUpdate Finesse code for cavity scan

The cavity scan data obtained from the Finesse simulation is attached here. Fig1 indicates the cavity scan data in the absence of induced misalignment. In that case only the fundemental mode is resonating. But when a misalignment is induced, higher order modes are also present as seen in Fig2. This is in the absence of surface figure error in the mirrors. Now I am trying to provide perturbations to the mirror surface in the form of zernike polynomials and get the scan data fom the simulation. These cavity scan data can be used to develop fitting models. Once we have a model, we can use it to analyse the data from the experimental cavity scan.

Attachment 1: Fig1.png
Attachment 2: Fig2.png
13928   Thu Jun 7 20:19:53 2018 poojaUpdate

Just to inform, I'm working in optimus to develop python code to train the neural network since it requires a lot of memory.

13956   Wed Jun 13 18:08:36 2018 keerthanaUpdate Finesse code for cavity scan

The unit mentioned in the x-axis was wrong. So I have remade the graphs. The point where frequency equals to zero is actually the frequency corresponding to the laser, which is in the range of 1014 Hz and it caliberated as zero.

 Quote: The cavity scan data obtained from the Finesse simulation is attached here. Fig1 indicates the cavity scan data in the absence of induced misalignment. In that case only the fundemental mode is resonating. But when a misalignment is induced, higher order modes are also present as seen in Fig2. This is in the absence of surface figure error in the mirrors. Now I am trying to provide perturbations to the mirror surface in the form of zernike polynomials and get the scan data fom the simulation. These cavity scan data can be used to develop fitting models. Once we have a model, we can use it to analyse the data from the experimental cavity scan.
Attachment 1: finesse1.pdf
Attachment 2: finesse2.pdf
13994   Thu Jun 21 09:33:02 2018 JonUpdate AUX Mode Scans of YARM, PRC cavities

[Jon, Keerthana, Sandrina]

Yesterday we carried out preliminary proof-of-concept measurements using the new AS-port-injected AUX laser to resolve cavity mode resonances.

At the time we started, I found the beat note levels consistent with what Johannes had reported the night before post-realignment. Hence we did not change the AUX alignment.

Test 1: YARM Mode Scan

• IFO locked in YARM configuration on carrier.
• Confirmed the presence of a -80 dBm beat note on the temporary YEND broadband PD (i.e., at the cavity transmission).
• Slowly canned the RF offset of the AUX laser from 50 MHz (nominal) to 60 MHz in 10 kHz steps.
• Attachment 1 shows the measured scan in "max hold" mode. The bottom panel is the transmission spectrum and the top panel is the reflection, with the AUX/PSL carrier-carrier beat note visible to the far left. In addition to the FSR, it looks to me like the scan resolves at least two HOMs.

Test 2: PRC Mode Scan

• IFO locked in PRMI configuration on carrier.
• Moved the temporary 150 MHz PDA10CF from the YEND to an unused pickoff of the REFL33 beam (i.e., the PRC transmission of the AUX beam). There was an existing 50-50 beamsplitter just before REFL33 whose reflected beam was directed onto a beam dump. The PD is now placed in that location. The modification to the AS table is shown in Attachment 2.
• We made a similar slow scan of the AUX RF offset over ~35 MHz in 10 kHz steps.
• We resolve the 22 MHz FSR, but it is apparent that an incoherent "max-hold" analyzer measurement is inadequate. The problem is that in max-hold mode, because the 11 MHz-spaced PSL sidebands also beat with the AUX subcarrier, we measure a messy superposition of the PSLcarrier-AUXcarrier beat AND all of the PSLsideband-AUXcarrier beats. The next step is to use the AOM to make a coherent measurement at only the frequency of PSL/AUX carrier-carrier beat.

The SURFs have the data from last night's scans and will be separately posting plots of these measurements. We'll continue today with mode scans using AM sidebands rather than the AUX RF offset.

Attachment 1: YARM_AUX_RF-offset_scan.pdf
14005   Fri Jun 22 10:42:52 2018 poojaUpdate Developing neural networks

Aim: To find a model that trains the simulated data of Gaussian beam spot moving in a vertical direction by the application of a sinusoidal signal.

All the attachments are in the zip folder.

The simulated video of beam spot motion without noise (amplitude of sinusoidal signal given = 20 pixels) is given in this link https://drive.google.com/file/d/1oCqd0Ki7wUm64QeFxmF3jRQ7gDUnuAfx/view?usp=sharing

I tried several cases:

Case 1:

I added random uniform noise (ranging from 0 to 25.5 i.e. 10% of the maximum pixel value 255) using opencv to 64*64 simulated images made in the last case( https://nodus.ligo.caltech.edu:8081/40m/13972), clipped the pixel values from 0 to 255 & trained using the same network as in the previous elog and it worked well. The variation in mean squared error with epochs is given in Attachment 1 & applied signal and output of the neural network (NN) (magnitude of the signal vs time) as well as the residual error is given in Attachment 2.

Case 2:

I simulated images 128*128 at 10 frames/sec by applying a sine wave of frequency 0.2Hz that moves the beam spot & resized it using opencv to 64*64. Then I trained 300cycles & tested with 1000 cycles with the following sequential model:

(i) Layers and number of nodes in each:

4096 (dropout = 0.1) -> 1024 (dropout = 0.1) -> 512 (dropout = 0.1) -> 256  ->  64 ->  8   ->   1

Activation :                        selu                   ->                 selu             ->         selu                -> selu ->  selu -> selu -> linear

(ii) loss function = mean squared error ( I used mean squared error to easily comprehend the result. Initially I had tried log(cosh) also but unfortunately I had stopped the run in between when test loss value had no improvement), optimizer = Nadam with default learning rate = 0.002

(iii) batch size = 32, no. of epochs = 400

I have attached the variation in loss function with epochs (Attachment 3). It was found that test loss value increases after ~50 epochs. To avoid overfitting, I added dropout to the layer of 256 nodes in the next model and removed the layer of 4096 nodes.

Case 3

Same simulated data as case 2 trained with the following model,

(i) Layers and number of nodes in each:

1024 (dropout = 0.1) -> 512 (dropout = 0.1) -> 256 (dropout = 0.1) ->  64 ->  8   ->   1

Activation :                              selu             ->         selu                ->              selu ->             selu -> selu -> linear

(ii) changed the learning rate from default value of 0.002 to 0.001. Rest of the hyperparameters same.

The variation in mean squared error in attachment 4  & NN output, applied signal & residual error (zoomed) in attachment 5. Here also test loss value increases after ~65 epochs but this fits better than the previous model as loss value is less.

Case 4:

Since in most of the examples in keras, training dataset was more than test dataset, I tried training 1000 cycles & testing with 300 cycles. The respective plots are attached as attachment 6 & 7. Here also, there is no significant improvement except that the test loss is increasing at a slower rate with epochs as compared to the last case.

Case 5:

Since most of the above cases were like overfitting (https://machinelearningmastery.com/diagnose-overfitting-underfitting-lstm-models/, https://github.com/keras-team/keras/issues/3755) except that test loss is less than train loss value in the beginning , I tried implementing case 4 with the initial model of 2 layers of 256 nodes each but with Nadam optimizer. Respective graphs in attachment 8, 9 & 10(zoomed). The loss value is slightly higher than the previous models as seen from the graph but test & train loss values converge after some epochs.

I have forgot to give ylabel in some of the graphs. It's the magnitude of the applied sine signal to move the beam spot. In most of the cases, the network almost correctly fits the data and test loss value is lower in the initial epochs. I think it's because of the dropout we added in the model & also we are training on the clean dataset.

Attachment 1: NN_fig.zip
14045   Sun Jul 8 22:27:25 2018 keerthanaUpdate AUX diagram

(Analisa, Keerthana, Sandrine)

So far we tried four different techniques to scan the AUX laser. They are,

1. Scanning the marconi frequency to sweep the central frequency of the AUX laser.

2. Sweeping the side band frequency of the AUX laser by providing RF frequency from the spectrum analyser.

3. Double demodulation technique.

4. Single demodulation technique.

Now we are taking all the scan data with the help of Single demodulation technique.

Attachment 1: PLL-single_demodulation.pdf
Attachment 2: PLL-double_demodulation.pdf
14058   Thu Jul 12 15:15:47 2018 SandrineUpdate Beat Note Measurements for Cavity Scans

(Gautam, Sandrine)

We calculated the expected power of the beat note for Annalisa's Y arm cavity scans.

Beat Note Measurement

We began by calculating the transmitted power of the PSL and AUX. We assumed that the input power of the PSL was 25 mW and the input power of the AUX was 250 uW. We also assumed a loss of 25 ppm for the ITM and ETM. We used T1 = 0.0138 and T2 = 25 x 10-6.

$P_{t} = \frac{t _{1}^{2}t_{2}^{2}}{1+r_{1}^{2}r_{2}^{2}-2r_{1}r_{2}}$

$t = \sqrt{T}$

$r = \sqrt{1-T-L} = {\sqrt{R}}$

The transmitted power of the PSL is approximately 100 uW, and the transmitted power of the AUX is approximately 0.974 uW.

$P_{t}^{PSL} = 100 uW$                          $P_{t}^{AUX} = 0.974 uW$

The beat note was calculated with the following:

$P_{beat} = 2\sqrt{P_{PSL}P_{AUX}} = 20 uW$

The  expected beat note should be approximately 20 uW.

14111   Sat Jul 28 22:16:49 2018 John MartynUpdate Characterization of Transimpedance Amplifier

Kevin and I meaured the transfer function of the photodiode circuit using the Jenne laser and agilent in the 40m lab. The attached figures depict our measured transfer function over the modulation frequency ranges of 30kHz-30MHz and 1kHz-30MHz when the power of the laser was set to 69 and 95 μW. These plots indicate a clear roll off frequency around 300 kHz. In addition, the plots beginning at 1kHz display unstable behavior at frequencies below 30kHz. I am not sure why there is such a sharp change in the transfer function around 30kHz, but I suspect this to be due to an issue with the agilent or photodiode.

Attachment 1: PD_TF1.pdf
Attachment 2: PD_TF2.pdf
Attachment 3: PD_and_TIA_Transfer_Function_Measurements.zip
14278   Tue Nov 6 19:41:46 2018 JonOmnistructure c1vac1/2 replacement

This afternoon I started setting up the Supermicro 5017A-EP that will replace c1vac1/2. Following Johannes's procedure in 13681 I installed Debian 8.11 (jessie). There is a more recent stable release, 9.5, now available since the first acromag machine was assembled, but I stuck to version 8 for consistency. We already know that version to work. The setup is sitting on the left side of the electronics bench for now.

14282   Wed Nov 7 19:17:18 2018 JonOmnistructure modbusIOC is running on c1vac replacement

Today I finished setting up the server that will replace the c1vac1/2 machines. I put it on the martian network at the unassigned IP 192.168.113.72. I assigned it the hostname c1vac and added it to the DNS lookup tables on chiara.

I created a new targets directory on the network drive for the new machine: /cvs/cds/caltech/target/c1vac. After setting EPICS environment environment variables according to 13681 and copying over (and modifiying) the files from /cvs/cds/caltech/target/c1auxex as templates, I was able to start a modbusIOC server on the new machine. I was able to read and write (soft) channel values to the EPICS IOC from other machines on the martian network.

I scripted it as a systemd-managed process which automatically starts on boot and restarts after failure, just as it is set up on c1auxex.

14287   Fri Nov 9 22:24:22 2018 JonOmnistructure Wiring of Vacuum Acromag Chassis Complete

Wiring of the power, Ethernet, and indicator lights for the vacuum Acromag chassis is complete. Even though this crate will only use +24V DC, I wired the +/-15V connector and indicator lights as well to conform to the LIGO standard. There was no wiring diagram available, so I had to reverse-engineer the wiring from the partially complete c1susaux crate. Attached is a diagram for future use. The crate is ready to begin software developing on Monday.

Attachment 1: IMG_2987.jpg
Attachment 2: IMG_2985.jpg
Attachment 3: IMG_2986.jpg
14296   Wed Nov 14 21:34:44 2018 JonOmnistructure Vacuum Acromags installed and tested

All 7 Acromag units are now installed in the vacuum chassis. They are connected to 24V DC power and Ethernet.

I have merged and migrated the two EPICS databases from c1vac1 and c1vac2 onto the new machine, with appropriate modifications to address the Acromags rather than VME crate.

I have tested all the digital output channels with a voltmeter, and some of the inputs. Still more channels to be tested.

I’ll follow up with a wiring diagram for channel assignments.

Attachment 1: IMG_3003.jpg
14308   Mon Nov 19 22:45:23 2018 JonOmnistructure Vacuum System Subnetwork

I've set up a closed subnetwork for interfacing the vacuum hardware (Acromags and serial devices) with the new controls machine (c1vac; 192.168.113.72). The controls machine has two Ethernet interfaces, one which faces outward into the martian network and another which faces the internal subnetwork, 192.168.114.xxx. The second network interface was configured via the following procedure.

1. Add the following lines to /etc/network/interfaces:

allow-hotplug eth1
iface eth1 inet static
netmask 255.255.255.0

2. Restart the networking services:

$sudo /etc/init.d/networking restart 3. Enable DNS lookup on the martian network by adding the following lines to /etc/resolv.conf: search martian nameserver 192.168.113.104 4. Enable IP forwarding from eth1 to eth0: $sudo echo 1 > /proc/sys/net/ipv4/ip_forward

5. Configure IP tables to allow outgoing connections, while keeping the LAN invisible from outside the gateway (c1vac):

$sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE$sudo iptables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT \$sudo iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT

6. Finally, because the EPICS 3.14 server binds to all network interfaces, client applications running on c1vac now see two instances of the EPICS server---one at the outward-facing address and one at the LAN address. To resolve this ambiguity, two additional enviroment variables must be set that specify to local clients which server address to use. Add the following lines to /home/controls/.bashrc:

EPICS_CA_AUTO_ADDR_LIST=NO
EPICS_CA_ADDR_LIST=192.168.113.72

A list of IP addresses so far assigned on the subnetwork follows.

 Device IP Address Acromag XT1111a 192.168.114.1 Acromag XT1111b 192.168.114.2 Acromag XT1111c 192.168.114.3 Acromag XT1111d 192.168.114.4 Acromag XT1111e 192.168.114.5 Acromag XT1121a 192.168.114.6 Acromag XT1121b 192.168.114.7 Perle IOLAN SDS16 192.168.114.8 c1vac 192.168.114.9
14309   Mon Nov 19 23:38:41 2018 JonOmnistructure Vacuum Acromag Channel Assignments

I've completed bench testing of all seven vacuum Acromags installed in a custom rackmount chassis. The system contains five XT1111 modules (sinking digital I/O) used for readbacks of the state of the valves, TP1, CP1, and the RPs. It also contains two XT1121 modules (sourcing digital I/O) used to pass 24V DC control signals to the AC relays actuating the valves and RPs. The list of Acromag channel assignments is attached.

I tested each input channel using a manual flip-switch wired between signal pin and return, verifying the EPICS channel readout to change appropriately when the switch is flipped open vs. closed. I tested each output channel using a voltmeter placed between signal pin and return, toggling the EPICS channel on/off state and verifying the output voltage to change appropriately. These tests confirm the Acromag units all work, and that all the EPICS channels are correctly addressed.

Attachment 1: Binary_IO_Channel_Assignments.pdf
14315   Sun Nov 25 17:41:43 2018 JonOmnistructure Vacuum Controls Upgrade - Status and Plans

New hardware has been installed in the vacuum controls rack. It is shown in the below post-install photo.

• Supermicro server (c1vac) which will be replacing c1vac1 and c1vac2.
• 16-port Ethernet switch providing a closed local network for all vacuum devices.
• 16-port IOLAN terminal server for multiplexing/Ethernetizing all RS-232 serial devices.

Below is a high-level summary of where things stand, and what remains to be done.

## Completed:

Set up of replacement controls server (c1vac).

• Supermicro 1U rackmount server, running Debian 8.5.
• Hosting an EPICS modbus IOC, scripted to start/restart automatically as a system service.
• First Ethernet interface put on the martian network at 192.168.113.72.
• Second Ethernet interface configured to host a LAN at 192.168.114.xxx for communications with all vacuum electronics. It connects to a 16-port Ethernet switch installed in the vacuum electronics rack.
• Server installed in vacuum electronics rack (see photo).

Set up of Acromag terminals.

• 6U rackmount chassis frame assembled; 15V DC, 24V DC, and Ethernet wired.
• Acromags installed in chassis and configured for the LAN (5 XT1111 units, 2 XT1121 units).

EPICS database migration.

• All vacuum channels moved to the modbus IOC, with the database updated to address the new Acromags. [The new channels are running concurrently at "C1:Vac2-...." to avoid conflict with the existing system.]
• Each hard channel was individually tested on the electronics bench to confirm correct addressing and Acromag operation.

Set up of 16-port IOLAN terminal server (for multiplexing/Ethernetizing the serial devices).

• Configured for operation on the LAN. Each serial device port is assigned a unique IP address, making the terminal server transparent to client TCP applications.
• Most of the pressure gauges are now communicating with the controls server via TCP.

## Ongoing this week:

• [Jon] Continue migrating serial devices to ports on the terminal server. Still left are the turbo pumps, N2 gauge, and RGA.
• [Jon] Continue developing Python code for communicating with gauges and pumps via TCP sockets. A beta version of gauge readout code is running now.
• [Chub] Install feedthrough panels on the Acromag chassis. Connect the wiring from feedthrough panels to the assigned Acromag slots.
• [Chub/Jon] Test all the hard EPICS channels on the electronics bench, prior to installing the crate in the vacuum rack.
• [Chub/Jon] Install the crate in the vacuum rack; connect valve/pump readbacks and actuators; test each hard EPICS channel in situ.
• [Jon] Once all the signal connections have been made, in situ testing of the Python interlock code can begin.
Attachment 1: rack_photo.jpg
14320   Mon Nov 26 21:58:08 2018 JonOmnistructure Serial Vacuum Signals

All the serial vacuum signals are now interfaced to the new digital controls system. A set of persistent Python scripts will query each device at regular intervals (up to ~10 Hz) and push the readings to soft channels hosted by the modbus IOC. Similar scripts will push on/off state commands to the serial turbo pumps.

Each serial device is assigned an IP address on the local subnet as follows. Its serial communication parameters as configured in the terminal server are also listed.

Device IP Address Baud Rate Data Bits Stop Bits Parity
MKS937a vacuum gauge controller 192.168.114.11 9600 8 1 even
MKS937b vacuum gauge controller 192.168.114.12 9600 8 1 even
GP307 vacuum gauge controller 192.168.114.13 9600 8 1 even
GP316a vacuum gauge controller 192.168.114.14 9600 8 1 even
GP316b vacuum gauge controller 192.168.114.15 9600 8 1 even
N2 pressure line gauge 192.168.114.16 9600 7 1 odd
TP2/3 192.168.114.17/18 9600 8 1 none

## Hardware Modifications

• Each of the five vacuum gauge controllers has an RJ45 adapter installed directly on its DB9/DB25 output port. Because the RJ45 cable now plugs directly into the terminal server, instead of passing through some additional adapters as it formerly did, it was necessary to reverse the wiring of the controller TXD and RXD pins to Ethernet pins. The DB9/25-to-RJ45 adapters on the back of the controllers are now wired as follows.
• For the MKS controllers: DB2 (RXD) --> Eth4;  DB3 (TXD) --> Eth5;  DB5 (RTN) --> Eth6
• For the Granville-Phillips controllers: DB2 (TXD) --> Eth5;  DB3 (RXD) --> Eth4;  DB7 (RTN) --> Eth6
• I traced a communications error with the GP307 gauge controller all the way back to what I would have suspected least, the controller itself. The comm card inside each controller has a set of mechanical relay switches which set the communications parameters (baud rate, parity, etc.). Knowing that this controller was not part of the original installation, but was swapped in to replace the original in 2009, I pulled the controller from the rack and checked the internal switch settings. Sure enough, the switch settings (pictured below) were wrong. In the background of the photo is the unit removed in 2009, which has the correct settings. After setting the correct communications parameters, the controller immediately began communicating with the server. Did these readouts (PRP, PTP1) never work since 2009? I don't see how they could.
Attachment 1: GP307_relays.jpeg
14420   Tue Jan 29 16:12:21 2019 ChubUpdate

The foam in the cable tray wall passage had been falling on the floor in little bite-sized pieces, so I investigated and found a fiber cable that had be chewed/clawed through.  I didn't find any droppings anywhere in the 40m, but I decided to bait an un-set trap and see if we'd find activity around it. There has been none so far.  If there is still none tomorrow, I will move the trap and keep looking for signs of rodentia.  At the moment, the trap is in a box in front of the double doors at the north end of the control room.  Next it will be place in the IFO room, up in the cable tray.

gautam: the fiber that was damaged was the one from the LSC rack FiBox to the control room FiBox. So no DAFI action for a bit...

14435   Tue Feb 5 10:22:03 2019 chubUpdate oil added to RP-1 & 3

I added lubricating oil to roughing pumps RP1 and RP3 yesterday and this morning.  Also, I found a nearly full 5 gallon jug of grade 19 oil in the lab.  This should set us up for quite a while.  If you need to add oil the the roughing pumps, use the oil in the quart bottle in the flammables cabinet.  It is labeled as Leybold HE-175 Vacuum Pump Oil.  This bottle is small enough to fill the pumps in close quarters.

14437   Wed Feb 6 10:07:23 2019 ChubUpdate pre-construction inspection

The Central Plant building will be undergoing seismic upgrades in the near future.  The adjoining north wall along the Y arm will be the first to have this work done, from inside the Central Plant.  Project manager Eugene Kim has explained the work to me and also noted our concerns.  He assured me that the seismic noise from the construction will be minimized and we will always be contacted when the heaviest construction is to be done.

Tomorrow at 11am, I will bring Mr. Kim and a few others from the construction team to look at the wall from inside the lab.  If you have any questions or concerns that you want to have addressed, please email them to me or contact Mr. Kim directly at x4860 or through email at eugene.kim@caltech.edu .

14476   Fri Mar 8 08:40:26 2019 AnjaliConfiguration Frequency stabilization of 1 micron source

The schematic of the homodyne configuration is shown below.

Following are the list of components

 Item Quantity Availability Part number Remarks Laser (NPRO) 1 Yes Couplers (50/50) 5 3 No's FOSC-2-64-50-L-1-H64F-2 Fiber type : Hi1060 Flex fiber Delay fiber two loops of 80 m Yes PM 980 One set of fiber is now kept along the arm of the interferometer InGaAs PD (BW > 100 MHz) 4 Yes NF1611 Fiber coupled (3 No's) Free space ( 2 No's) SR560 3 Yes
• The fiber mismatch between the couplers and the delay fiber could affect the coupling efficiency
Attachment 1: Homodyne_setup.png
14621   Sat May 18 12:19:36 2019 KruthiUpdate CCD calibration and telescope design

I went through all the elog entries related to CCD calibration. I was wondering if we can use Spectralon diffuse reflectance standards (https://www.labsphere.com/labsphere-products-solutions/materials-coatings-2/targets-standards/diffuse-reflectance-standards/diffuse-reflectance-standards/) instead of a white paper as they would be a better approximation to a Lambertian scatterer.

Telescope design:
On calculating the accessible u-v ranges and the % error in magnification (more precisely, %deviation), I got %deviation of order 10 and in some cases of order 100 (attachments 1 to 4), which matches with Pooja's calculations. But I'm not able reproduce Jigyasa's %error calculations where the %error is of order 10^-1. I couldn't find the code that she had used for these calculations and I even mailed her about the same. We can still image with 150-250 mm combination as proposed by Jigyasa, but I don't think it ensures maximum usage of pixel array. Also for this combination the resulting conjugate ratio will be greater than 5. So, use of plano-convex lenses will reduce spherical aberrations. I also explored other focal length combinations such as 250-500 mm and 500-500mm. In these cases, both the lenses will have f-numbers greater than 5. But the conjugate ratios will be less than 5, so biconvex lenses will be a better choice.

Constraints: available lens tube length (max value of d) = 3" ; object distances range (u) = 70 cm to 150 cm ; available cylindrical enclosures (max value of d+v) are 52cm and 20cm long (https://nodus.ligo.caltech.edu:8081/40m/13000).

I calculated the resultant image distance (v) and the required distance between lenses (d), for fixed magnifications (i.e. m = -0.06089 and m = -0.1826 for imaging test masses and beam spot respectively) and different values of 'u'. This way we can ensure that no pixels are wasted. The focal length combinations - 300-300mm (for imaging beam spot), and 100-125mm (for imaging test masses) - were the only combinations that gave all positive values for 'd' and 'v', for given range of 'u' (attachments 5-6). But here 'd' ranges from 0 to 30cm in first case, which exceeds the available lens tube length. Also, in the second case the f-numbers will be less than 5 for 2" lenses and thus may result in spherical aberration.

All this fuss about f-numbers, conjugate ratios, and plano-convex/biconvex lenses is to reduce spherical aberrations. But how much will spherical aberrations affect our readings?

We have two 2" biconvex lenses of 150mm focal length and one 2" biconvex lens of focal length 250mm in stock. I'll start off with these and once I have a metric to quantify spherical aberrations we can further decide upon lenses to improve the telescopic lens system.

Attachment 1: 15-25.png
Attachment 2: 25-25.png
Attachment 3: 25-50.png
Attachment 4: 50-50.png
Attachment 5: 30-30_for_1%22.png
Attachment 6: 10-12.5_for_3%22.png
14626   Mon May 20 21:45:20 2019 MilindUpdate Traditional cv for beam spot motion

Went through all of Pooja's elog posts, her report and am currently cleaning up her code and working on setting up the simulations of spot motion from her work last year. I've also just begun to look at some material sent by Gautam on resonators.

This week, I plan to do the following:

1) Review Gabriele's CNN work for beam spot tracking and get his code running.

2) Since the relation between the angular motion of the optic and beam spot motion can be determined theoretically, I think a neural network is not mandatory for the tracking of beam spot motion. I strongly believe that a more traditional approach such as thresholding, followed by a hough transform ought to do the trick as the contours of the beam spot are circles. I did try a quick and dirty implementation today using opencv and ran into the problem of no detection or detection of spurious circles (the number of which decreased with the increased application of median blur). I will defer a more careful analysis of this until step (1) is done as Gautam has advised.

3) Clean up Pooja's code on beam tracking and obtain the simulated data.

4) Also data like this  (https://drive.google.com/file/d/1VbXcPTfC9GH2ttZNWM7Lg0RqD7qiCZuA/view) is incredibly noisy. I will look up some standard techniques for cleaning such data though I'm not sure if the impact of that can be measured until I figure out an algorithm to track the beam spot.

A more interesting question Gautam raised was the validity of using the beam spot motion for detection of angular motion in the presence of other factors such as surface irregularities. Another question is the relevance of using the beam spot motion when the oplevs are already in place. It is not immediately obvious to me how I can ascertain this and I will put more thought into this.

14782   Fri Jul 19 22:48:08 2019 KruthiUpdate Dataviewer error

I'm not able to get trends of the TM adjustment test that Rana had asked us to perform, from the dataviewer. It's throwing the following error:

Connecting to NDS Server fb (TCP port 8088)
Connecting.... done
Server error 7: connect() failed
datasrv: DataWrite failed: daq_send: Resource temporarily unavailable
T0=19-07-20-01-27-39; Length=600 (s)
No data output.

ELOG V3.1.3-