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ID Date Author Type Categoryup Subject
  16024   Tue Apr 13 20:45:16 2021 YehonathanUpdatePSLLaser amplifier

{Yehonathan, Rana}

We unpacked the content of the amplifier crate in front of the water fountain (see attachments). Inside we found:

1. Amplifier head. (attachment 1)
2. Amplifier electronics and pump diodes (attachment 2).
3. Optical fiber (attachment 3).
4. 2 Long water hoses (~2m) and 2 short ones.
5. Network cable.
6. A wooden plate.
7. Cable sleeve (attachment 2)?
8. Some manuals will be uploaded to the wiki soon.

Please don't move/touch any of that stuff

Things that we need to consider/obtain:
1. A suitable power cable (attachment 4) with suitable power ratings (800W according to the amplifier specs). The connector head is C19 I believe.
2. A chiller. Rana says Aidan knows where to find one. Should we chill the amplifier head as well?
3. A mounting plate for the amplifier head with good thermal conductivity.
4. The pump wavelength is 808nm, we need to get suitable safety goggles.
5. Where to put the big electronics box. Preferably on 1X1 or 1X2.
6. How do we arrange the different components on the table? We also need to mode match the beam into the amplifier.

 

Attachment 1: 20210413_204721.jpg
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Attachment 2: 20210413_203300.jpg
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Attachment 3: 20210413_204940.jpg
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Attachment 4: 20210413_205549.jpg
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  16032   Wed Apr 14 19:48:18 2021 gautamUpdatePSLLaser amplifier

A couple of years ago, I got some info about the amplifier setup at the sites from Terra - sharing here in case there is some useful info in there (our setup will be rather different, but it looked to me like our Amp is a 2017 vintage and it may be that the performance is not the same as reported in the 2019 paper).

collection of docs (table layout in 'Proposed....setup') : https://dcc.ligo.org/LIGO-T1700046

LVC 70W presentation: https://dcc.ligo.org/LIGO-G1800538 

I guess we should double check that the beam size everywhere (in vacuum and on the PSL table) is such that we don't exceed any damage thresholds for the mirrors used. 

  16034   Thu Apr 15 09:46:24 2021 YehonathanUpdatePSLLaser amplifier

Some more relevant documents provided by Matt:

Phase III:70W amplifier integration at LIGO

70W amplifier External Shutter

aLIGO PSL high power attenuator

 

  16044   Fri Apr 16 18:21:36 2021 YehonathanUpdatePSLLaser amplifier

I surveyed a bit the 1X1/2 area to plan for the installation of the laser amplifier.

There is a vacancy at the bottom of 1X2 (attachment 1). I measured the dimensions of the diode box (DB) and it should fit. The optical fiber bundle is 75m long and should reach the amplifier head on the table easily.

According to the specs, the maximum power consumption of the DB is 800W (typically 600W), it should probably have its own circuit breaker. It can easily draw more than a few amps. The rack power strips are connected to this 4 socket box (attachment 2), is this just another power strip? It is connected to a circuit breaker with a 30A rating. How do we proceed from here?

In any case, we will need at least 2 meters of power cable.

I also tried to find a suitable place for a water chiller. A few suggestions are in the attachments. Basically either between the electronics shelves and the small rack next to 1X2 or next to the small rack close to the optical table. Maybe put it where the ladder sits and find another place for the ladder. Other options?

We would also need a windows machine running the Beckhoff software. The idea is that all the different laser components (DB, chillers, interlocks, switches) are connected to the EtherCat (over the ethernet infrastructure) so that the Beckhoff code can recognize a failure and switch off everything.

The things that are monitored:

1. Is the NPRO on?

2. Is the flow rate from the chillers enough?

3. Is the temperature of the diodes in the normal range?

4. Is one of the interlocks open?

5. Was one of the emergency buttons pushed?

6. Was the key switch on the DB turned to OFF?

The DB is EtherCat ready but the rest of the signals need to be interfaced somehow. Do we have to buy these EtherCAT terminals?

 

 

Attachment 1: 20210416_143642.jpg
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Attachment 2: 20210416_145408.jpg
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Attachment 3: 20210416_145448.jpg
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Attachment 4: 20210416_181324.jpg
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  16046   Sun Apr 18 21:29:55 2021 ranaUpdatePSLLaser amplifier
  • Ideally, we put the chiller outside of the interferometer area. The PSL chiller used to be in the control room near the door by IMC REFL. We could also put it in the drill press room.
  • Once we figure out a couple of places where the Diode Box can go, we can ask facilities to make the appropriate power connections. They will have to eval the situation to figure out if the main power to the lab needs to be shut down.
  • Can we put the laser diode box in the drill press room too? Then the hoses can be short. Perhaps less EMI getting into our sensitive places.
  16056   Wed Apr 21 00:08:15 2021 KojiUpdatePSLPSL Table (sort of) covered / HEPA "chimney"

Shutdown Procedure:
PSL Shutter closed / MC Autolocker disabled / PSL mechanical shutter closed / Laser injection current turned to zero / Laser turn off (red button) / Laser key turned off

The laser stat before the shutdown:
- LD Temp A: Set 22.07 (Untouched)
- LD Temp B: Set 21.03(Untouched)
- Laser Injection Current: Dial 9.53, Actual 2.100 -> Dial was moved to zero upon shutting down
- Laser Crystal Temp: Dial 3.34 (untouched)  Set 30.57 Actual 30.60 (Untouched)

PSL Table covering

- Because of the so many cables going up and down, sealing the PSL table with the metalized sheet was not easy. Therefore, the sheets have been just softly laid above the optics. (Attachment 1)
- The largest sheet which covers the east half of the table was taped to the table at the bottom, so that the air from the chimneys (see below) does not come up to the table

- The large dust could come from the opening of the enclosure during the filter replacement. So it was considered to be easier to seal the openings. (Attachment 2)
- Of course, the HEPAs are going to be tested after the maintenance work. It means that vent paths were needed so that the seals do not explode with the pressure (together with dust).
- Thus, the tubes of the sheets are attached to the seals to form "chimneys" for guiding the airflow beneath the table. (Attachment 2/3/4)
- This configuration was not meant to be sufficiently strong for a continuous run of the fans. Long running of the HEPAs may cause the failure of the seal tapes.
  Therefore the HEPA test should be done with a low flow rate and/or a short period of high flow.

- Once the work has been done, all the sheets should be carefully removed without scattering the fallouts onto the optics.

 

Attachment 1: 20210420235324_IMG_0560.jpeg
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Attachment 2: 20210420235304_IMG_0559.jpeg
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Attachment 3: 20210420235243_IMG_0558.jpeg
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Attachment 4: 20210420235344_IMG_0562.jpeg
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  16057   Wed Apr 21 01:14:03 2021 KojiUpdatePSLPSL Table (sort of) covered / HEPA "chimney"

I also located the (possible) HEPA filters in the lab. (Attachments 1~3)

Oh! This is NO-NO! We can't place anything in front of the mains breakers. (Attachment 2)
I relocated the objects (Attachment 3)

 

Attachment 1: P_20210421_005056.jpg
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Attachment 2: P_20210421_005114.jpg
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Attachment 3: P_20210421_005302.jpg
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  16062   Wed Apr 21 11:09:57 2021 yehonathanUpdatePSLLaser amplifier

I went to the TCS lab to take a look at the chillers lying around. I spotted two chillers:

1. Thermoflex1400 (attachment 1,2). Spec sheet.

2. Polyscience Recirculator 6000 series (attachment 3,4). Manual.

The Thermoflex has various communication ports. The Recirculator doesn't have any communication ports, but it is connected to a flow meter with what seems to be an electronic readout (attachment 5). Manual.

Both chillers have similar capacity ~ 4 gallons/minute. Thermoflex has 2 times more reservoir capacity than the Recirculator.

None of them seem to be Bechkoff-ready.

I guess we can have interlock code handling mixed signals Beckhoff+Non beckhoffs?

Attachment 1: 20210420_171606.jpg
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Attachment 2: 20210420_171621.jpg
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Attachment 3: 20210420_171611.jpg
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Attachment 4: 20210420_171629.jpg
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Attachment 5: 20210420_171702.jpg
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  16068   Wed Apr 21 19:28:03 2021 AnchalUpdatePSLPSL/IFO recovery

[Anchal, Koji]

Removed the top sheet

  • Opened first from the door side so that any dust would spill outside.
  • Then rolled the sheet inward to meet in the middle.
  • Repeated this twice for the 2 HEPA filters.

Removed the sheets on the table

  • Lifted sheet up making sure the top side face outside always.
  • Rolled it sideways halfway through.
  • Cut down the sheet vertically.
  • Slided the doors to the other side and rolled the remaining half.
  • On the door side, the sheets above the ALS optics were simply lifted off.

Restarting PSL

  • Turned on the HEPAs at the max speed
  • Switched on laser to jsut above the threshold
    • Before the 1st eom, power was 20mW 
    • After the EOM/AOM, 18mW. So about 90% transmission through all polarizing optics.
    • We saw the resonances of the PMC but could not lock it even with highest gain available (30 dB).
  • Increased the input power to PMC to 100mW
    • Locked the PMC at 30dB gain
    • The transmitted power was ~50-60 mW. (Had to use power meter suspended by hand only.
    • The right before the IMC (after the 2nd EOM) 48mW. So none of the alignment was lost.
  • Opened the PSL shutter.
  • We were able to see IMC reflection signal.
  • We were also able to see IMC catching lock as the servo was left ON earlier.
  • Switched off the servo.
  • Decided to increase the power while watching PMC Trans/Refl and IMC REFL
  • Injection diode current to innolight was increased slowly to 2.10A. Saw a mod hopping region aroun 1.8A.
  • We recovered the PMC Trans >0.7 V.
  • PZT was near the edge, so moved by one FSR.
  • The PMC refelction signal is still shown in red at around 48 mV.

Back to control room

  • IMC was locked almost immediately by manually finding the lock while keeping IMC WFS off to preserve the offsets from yesterday.
  • Then switch on IMC WFS. Working good.
  • Then unlocked the servo and switched on IMC Autolocker. Lock was caught immediately.

Decided to start locking the arms

  • The arm transmissions were flashing but at 0.2~0.3 level.
  • Decided to adjust TT1 and TT2 Pitch and Yaw to align the light going into the arms.
  • This made TRY ~0.6 / TRX ~0.8 at the peak of the flashing
  • Locked the arms. (By switching on C1:LSC-MODE_SELECT which engages all servos).
  • Used ASS to align Yarm then align Xarm. Procedure:
    • Sitemap > ASC > c1ass
    • Open striptool to look at progress. ! Scripts YARM > striptool.
    • Switch on ASS. ! More Scripts > ON
    • Wait for the TRY to reach to around 0.97.
    • Freeze the outputs. ! Scripts > Freeze Outputs.
    • Offload the offsets to preserve the output. ! More Scripts > OFFLOAD OFFSETS.
    • Switch off ASS. ! More Scripts > OFF
    • Repeted this for XARM.
  • At the end, both XARM and YARM were locked with TRX ~ 0.97 and TRY ~ 0.96.
  16069   Wed Apr 21 19:43:20 2021 KojiUpdatePSLNew HEPA speed control

The new HEPA speed controllers are attached at the middle of the HEPA unit (not at the edge of the unit)... (Attachment 1)
You still need a step./stool to touch the knob and need a ladder for a more precise setting.

We still don't know the optimal speed of the nominal IFO operation. For now, the HEPAs are running at the max speed (Attachment 2).
Once we know the optimal setting, we mark the knobs so that we can see them only with the step.

Attachment 1: P_20210421_193637.jpg
P_20210421_193637.jpg
Attachment 2: P_20210421_193627.jpg
P_20210421_193627.jpg
  16074   Thu Apr 22 14:41:55 2021 ChubUpdatePSLNew HEPA speed control

When adjusting the blower speed, give the blower at least 30 seconds to speed up or slow down to the set speed.  The flywheel effect of the big motor armature and blower mass requires time to follow the control current.  Note the taller Flanders HEPA filters.  These and the new intake filters should keep the PSL air clean for a long time!

Quote:

The new HEPA speed controllers are attached at the middle of the HEPA unit (not at the edge of the unit)... (Attachment 1)
You still need a step./stool to touch the knob and need a ladder for a more precise setting.

We still don't know the optimal speed of the nominal IFO operation. For now, the HEPAs are running at the max speed (Attachment 2).
Once we know the optimal setting, we mark the knobs so that we can see them only with the step.

 

Attachment 1: 40M_PSL_HEPA.jpg
40M_PSL_HEPA.jpg
  16076   Thu Apr 22 15:15:26 2021 gautamUpdatePSLPMC transmission

I was a bit surprised by these numbers suggesting the PMC transmission is only 50-60%. I went to the table today and confirmed that it is more like 85% (1.3 W in, 1.1 W transmitted, both numbers from with the FieldMate power meter), as I claimed in 2019. Even being conservative with the power meter errors, I think we can be confident T_PMC will be >80% (modulo any thermal effects with higher power degrading the MM). There isn't any reliable record of what the specs of the PMC mirrors are, but assuming the IO couplers have T=4000ppm and the end mirror has T=500ppm as per Alan's plot, this is consistent with a loss of something like 300ppm loss per mirror - seems very high given the small beam spots, but maybe these mirrors just aren't as high quality as the test masses?

It's kind of unfortunate that we will lose ~20% of the amplifier output through the first filter, but I don't see an easy way to clean these mirrors. It's also not clear to me if there is anything to be gained by attempting a cleaning - isn't the inside of the cavity supposed to be completely isolated from the outside? Maybe some epoxy vaporization events degraded the loss?

Quote:

The transmitted power was ~50-60 mW. (Had to use power meter suspended by hand only.

  16077   Thu Apr 22 15:34:54 2021 AnchalUpdatePSLPMC transmission

Koji mentioned that the mode of the laser is different for lower diode currents. So that might be the reason why we got less transmission at the low input power but more afterward.

  16080   Thu Apr 22 17:28:34 2021 YehonathanUpdatePSLLaser amplifier

According to the aLIGO 70W amplifier interlock concept the flow rate of the chiller should be between 5 and 40 l/min. The chillers I found in the TCS lab both have around 15 l/min flow rate so we should be fine in that regard.

Assuming that the power consumption of the diode box is ~800W and that the optical output power of the diode is ~ 300W of optical power, the chillers need to be able to remove the remaining power. At room temperature, they both have enough cooling capacity according to their specs.

As for the idea to put the chiller and diode box in the drill room: There are not a lot of options here. The only viable place is the SW corner (attachment 1). I was told this place is used sometimes for liquid nitrogen dewar. Alternatively, if possible, we can move the fire extinguishers to the SW corner and use the NW corner. In that way, we don't have to clear all the junk from the SW corner, as long as the extinguishers are still accessible.

I made a sketch (attachment 2) showing a possible setup for a diode box + chiller rack. The fiber and network cable can go through the hole in the wall that already exists for the N2. It will have to get bigger though (attachment 3). The rack would also need to host some Acromag unit to convert the communication channel of the chiller/flow meter to Ethernet. The Acromag on 1X7 has no spare channels.

The only power socket in the room, to which the drill is connected, is circuit #36 which is connected to panel L in the lab. The breaker's ampacity seems to be 20A if I'm reading the number on the breaker correctly.

 

Attachment 1: 20210422_124940.jpg
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Attachment 2: DrillRoomSchematics.pdf
DrillRoomSchematics.pdf
Attachment 3: 20210422_125240_1.png
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  16082   Fri Apr 23 18:00:02 2021 gautamUpdatePSLHEPA speed lowered

I will upload some plots later - but in summary, I set the HEPA speed to ~40%. I used (i)IMC transmission RIN, (ii) Arm cavity transmission RIN and (iii) ALS beat noise as 3 diagnostics, to see how noise in various frequency bands for these signals change as a function of the HEPA speed. The MC2T RIN shows elevated noise between 1-10Hz at even the lowest speed I tried, ~20% of the max on each blower. The elevated noise extended to ~50-70 Hz for HEPA speeds >40% of the maximum, and the arm cavity RIN and ALS signals also start to become noisy for speeds >60% of the maximum. So I think 40% is a fine speed to run at - for squeezing measurement we may have to turn off the HEPA for 10mins but for the usual single arm / PRMI / DRMI locking, this should be just fine. For the elevated ALS noise - I'm not sure if the coupling is happening over the top of the enclosure where the fiber bringing light from EX comes close to the HEPA filters, or if it is happening inside the PSL enclosure itself, near the beat mouth - but anyways, at the 40% speed, I don't see any effect on the ALS noise.

I checked with a particle counter at the SW corner of the PSL table (which is the furthest away we can be on the table from the HEPA blowers) after leaving the blowers on for ~30mins and it registered 0 for both 0.3um and 0.5um sized particles (if the blowers are off, the respective numbers are 43 and 9 but I forgot what the units were, and I believe they have to be multiplied by 10). 

I have not yet marked the speed control units yet in case there is some other HEPA science that needs to be done before deciding what is the correct setting. But I think I can get the PRFPMI lock without much issue with this lower speed, which is what I will try later today evening.

Attachment 1: HEPAdiag.pdf
HEPAdiag.pdf
  16083   Fri Apr 23 19:26:58 2021 KojiUpdatePSLHEPA speed lowered

I believe that there is an internal setting for the minimum flow, so the flow is not linear ("0%" is not zero), but we should mark this flow speed once you find this is sufficiently low for the locking too.

  16141   Fri May 14 17:45:05 2021 ranaUpdatePSLHEPA speed raised

The PSL was too hot, so I turned on the south HEPA on the PSL. The north one was on and the south one was off (or so slow as to be inaudible and no vibration, unlike the north one). Lets watch the trend over the weekend and see if the temperature comes down and if the PMC / WFS variations get less. Fri May 14 17:46:26 2021

  16142   Sat May 15 12:39:54 2021 gautamUpdatePSLNPRO tripped/switched off

The NPRO has been off since ~1AM this morning it looks like. Is this intentional? Can I turn it back on (or at least try to)? The interlock signal we are recording doesn't report getting tripped but I think this has been the case in the past too.


After getting the go ahead from Koji, I turned the NPRO back on, following the usual procedure of diode current ramping. PMC and IMC locked. Let's see if this was a one-off or something chronic.

Attachment 1: NPRO.png
NPRO.png
  16144   Tue May 18 00:52:38 2021 ranaUpdatePSLHEPA speed raised

Looks like the fan lowered the temperature as expected. Need to get a few more days of data to see if its stabilized, or if that's just a fluke.

The vertical line at 00:00 UTC May 18 is about when I turned the fans up/on.

Attachment 1: Untitled.png
Untitled.png
  16145   Tue May 18 20:26:11 2021 ranaUpdatePSLHEPA speed raised

Fluke. Temp fluctuations are as usual, but the overall temperature is still lower. We ought to put some temperature sensors at the X & Y ends to see what's happening there too.

  16400   Thu Oct 14 09:28:46 2021 YehonathanUpdatePSLPMC unlocked

PMC has been unlocked since ~ 2:30 AM. Seems like the PZT got saturated. I moved the DC output adjuster and the PMC locked immidiatly although with a low transmission of 0.62V (>0.7V is the usual case) and high REFL.

IMC locked immidiately but IFO seems to be completely misaligned. The beams on the AS monitor are moving quite alot syncronously. BS watchdog tripped. I enabled the coil outputs. Waiting for the RMS motion to relax...

Its not relaxing. RMS motion is still high. I disabled the coils again and reenabled them. This seems to have worked. Arms were locked quite easily but the ETMs oplevs were way off and the ASS couldn't get the TRX and TRY more than 0.7. I align the ETMs to center the oplev. I realign everything else and lock the arms. Maximium TR is still < 0.8.

 

 

  16401   Thu Oct 14 11:25:49 2021 YehonathanUpdatePSLPMC unlocked

{Yehonathan, Anchal}

I went to get a sandwich around 10:20 AM and when I came back BS was moving like crazy. We shutdown the watchdog.

We look at the spectra of the OSEMs (attachment 1). Clearly, the UR sensing is bad.

We took the BS sattelite box out. Anchal opened the box and nothing seemed wrong visually. We returned the box and connected it to the fake OSEM box. The sensor spectra seemed normal.

We connected the box to the vacuum chamber and the spectra is still normal (attachment 2).

We turn on the coils and the motion got damped very quickly (RMS <0.5mV).

Either the problem was solved by disconnecting and connecting the cables or it will come back to haunt us.

 

 

 

Attachment 1: BS_OSEM_Sensor_PSD.pdf
BS_OSEM_Sensor_PSD.pdf
Attachment 2: BS_OSEM_Sensor_PSD_AfterReconnectingCables.pdf
BS_OSEM_Sensor_PSD_AfterReconnectingCables.pdf
  113   Fri Nov 16 18:46:49 2007 steveBureaucracyPSL MOPA was turned off & on
The "Mohana" boys scouts and their parents visited the 40m lab today.
The laser was turned off for their safety.
It is back on !
  2951   Wed May 19 14:36:46 2010 AidanHowToPhase CameraPhase Camera algorithm and stuff

 I had a think about the algorithm we might use for the phase camera measurement. MATLAB has an fft function that will allow us to extract the data that we need with a single command.

We record a series of images from a camera and put them into a 3D array or movie, image_arr, where the array parameters are [x-position, y-position, time], i.e. a 2D slice is a single frame from the camera. Then we can do an FFT on that object with the syntax, f3D = fft(image_arr, [ ], 3), which only does the FFT on the temporal components. The resulting object is a 3D array where each 2D slice is an 2D array of amplitude and phase information across the image for a single temporal frequency of the movie.

So if we recorded a movie for 1s where the sample rate is 58Hz, then the 1st frame of f3D is just a DC image of the movie, the 2nd frame are the complex 1Hz components of the movie, etc all the way up to 29Hz. 

Suppose then that we have a image, part of which is being modulated, e.g. a chopper wheel rotating at 20 or 24Hz, or a laser beam profile which contains a 1kHz beat between a sideband and a reference beam. All we have to do is sample at at least twice that modulation frequency, run the command in MATLAB, and then we immediately get an image which contains the phase and magnitude information that we're interested in (in the appropriate 2D slice o the FFT).

As an example, I recorded 58 frames of data from a camera, sampling at 58Hz, which was looking at a spinning chopper wheel. There was a white sheet of paper behind the wheel which was illuminated from behind by a flashlight. The outer ring was chopping at 24Hz and the inner ring was chopping at 20Hz. I stuck all the images into the 3D array in MATLAB, did the transformation and picked out the DC, 20Hz and 24Hz signals. The results are shown in the attached PDFs which are:

  1. phase_camera_DC_comp.pdf - a single image from the camera and the DC component (zoomed in) of the FFT
  2. phase_camera_F1_comp.pdf - the magnitude and phase information of the 20Hz component of the FFT
  3. phase_camera_F2_comp.pdf - the magnitude and phase information of the 24Hz component of the FFT (this PDF contains a typo that says 25Hz).
  4. load_raw_data.m - the MATLAB routine that loads the saved data from the camera and does the FFT

You can, and I have, run the MATLAB engine from C directly. This will allow you to transfer the data from the camera to MATLAB directly in memory, rather than via the disk, but it does need proper memory allocation to avoid segmentation faults - that was too frustrating for me in the short term. In this case, the 58 frames were recorded to a file as a contiguous block of data which I then loaded into MATLAB, so it was slower than it might've otherwise been. Also the computer I was running this on was a bit of a clunker so it took a bit of time to do the FFT.

The data rate from the camera was 58fps x (1024 x 1024) pixels per frame x 2 bytes per pixel = 116MB per second. If we were to use this technique in a LIGO phase camera, where we want to measure a modulation which is around 1kHz, then we'd need a sample rate of at least 2kHz, so we're looking at at least a 30x reduction in the resolution. This is okay though - the original phase camera had only ~4000 spatial samples. So we could use, for instance, the Dalsa Falcon VGA300 HG which can give 2000 frames per second when the region of interest is limited to 64 pixels high.

Attachment 1: phase_camera_DC_comp.pdf
phase_camera_DC_comp.pdf
Attachment 2: phase_camera_F1_comp.pdf
phase_camera_F1_comp.pdf
Attachment 3: phase_camera_F2_comp.pdf
phase_camera_F2_comp.pdf
Attachment 4: load_raw_data.m
% load a raw data file into MATLAB

fid = fopen('phase_camera_data.dat');
n1 = 750;
A3D = ones(n1, n1, 58);

for jj = 1:58
    A = fread(fid, [1024, 1024], 'uint16');
    A3D(:,:,jj) = A((512-floor(n1/2)):(512-floor(n1/2))+n1-1, ...
                    (512-floor(n1/2)):(512-floor(n1/2))+n1-1);
... 64 more lines ...
  2955   Thu May 20 10:06:56 2010 AidanHowToPhase CameraPhase Camera- raw data video


 

  3096   Tue Jun 22 09:45:21 2010 Aidan, Joe, RazibUpdatePhase CameraCurrent phase camera setup. Seeing Acoustic beat

 We've set up a preliminary test bed for the phase camera. It simply uses a HeNe that is split into two beams. One is frequency shifted by an AOM by -40 MHz - df, where df is some acoustic frequency. The second beam is transmitted through a 40MHz EOM to get sidebands. The two beams are recombined and are, currently, incident on a photodetector, but this can be replaced by the phasecamera.

We turned everything on with df = 1kHz and confirmed that a 1kHz signal is visible on the output from the photodetector (PD). The signal looks to be about 1:300 of the DC level from the PD.

Attachment 1: 2010-06-22_Phase_camera_layout_version_1.pdf
2010-06-22_Phase_camera_layout_version_1.pdf
  3097   Tue Jun 22 13:38:13 2010 KojiUpdatePhase CameraCurrent phase camera setup. Seeing Acoustic beat

1. In terms of the AOM:

How much beam power is incident on the AOM? How much is the deflection efficiency?
i.e. How much is the power lost by the crystal, deflected in the 1st order, and remaining in the oth order?

I am curious because I assume the AOM (which vender?) is designed for 1064nm and the setup uses 632nm.

2. In terms of the EOM:

How much sidebands do you expect to have?

I assume the EOM is designed for 1064nm, the only difference is the coating at the end. Is this right? 

3. Beating

How much beating strength do you expect?

Is your beating level as expected?

How much is the contrast between the PM sideband and the frequency shifted carrier?
This must include the consideration on the presence of the carrier and the other sidebands.

Quote:

 We've set up a preliminary test bed for the phase camera. It simply uses a HeNe that is split into two beams. One is frequency shifted by an AOM by -40 MHz - df, where df is some acoustic frequency. The second beam is transmitted through a 40MHz EOM to get sidebands. The two beams are recombined and are, currently, incident on a photodetector, but this can be replaced by the phasecamera.

We turned everything on with df = 1kHz and confirmed that a 1kHz signal is visible on the output from the photodetector (PD). The signal looks to be about 1:300 of the DC level from the PD.

 

  3102   Wed Jun 23 12:28:34 2010 RazibSummaryPhase CameraWeeekly Summary

This past week I have completed the following tasks:

 

1. Built a trigger and power box for the camera GC 750M (06058) and took some test images to see whether the trigger box really works. Result: It is doing fine!

2. Went over the setup that is already sitting on the table. Ref: Aidan's elog entry

3. Attended seminars and talks given by Alan, Jahms, Koji and Rana.

4. Attended the mandatory laser safety training by Peter.

 

Expected task for this week (could be more):

1. Work out analytical expressions of the power of the carrier and sidebands going to the camera in the setup. (As suggested by Rana and Joe)

2. Work on producing beat signal to the camera using the He-Ne laser setup.

3. Move,if possible, to the Nd:YAG setup.

4. Go over the codes and paper by the past SURFers on the phase camera experiment.

 

trigger-box_circuit.png

 


 

Attachment 2: test1.png
test1.png
  3146   Wed Jun 30 12:20:49 2010 RazibUpdatePhase CameraWeekly update

This week I have completed following tasks:

1. Worked out the analytical expressions for the amount of power of the DC and oscillatory part going into the camera.

2. Realigned the He-Ne PhaseCam setup as we had to replace the first steering mirror after the laser with a silvered mirror ( one without a dielectric coating for 1064 nm).

3. Gone through the code written by a previous surfer (Zach Cummings).

4. Read the paper 'Real-time phase-front detector for heterodyne interferometers'- F. Cervantes et. el. where they talk about constructing a phase detector for LISA pathfinder mission. One interesting fact I found was that, they used InGaAs chip for their CCD Cam which has a amazing QE of 80% @ 1064 nm. Unfortunately, the one we are using (Micro MT9V022 CMOS) has only ~5% QE for 1064 nm and 50% for 633 nm. One top of it MT9V022 has a built-in infra-red filter infront of it to make it more insenstive to 1064. In such limitations, we may have to find a work-around for this issue. Any idea?

5. Read about the EOM and AOM and their vibrating (!) way to add on and alter the incident light on them. (Source: Intro to Optical Electronics-Yariv)

 

One task that we couldn't accomplish even though I planned on doing is:

1. Move,if possible, to the Nd:YAG setup.

 

Task for this week:

1. Produce breathtaking calibration of the camera at He-Ne setup.

2. Read 'Fringe Analysis'-Y.Surrel and 'Phase Lock Technique'-Gardner.

3. Modify the phasecam code.

4. Produce an alternate triggerbox using diodes instead of Op-Amp as op-amp is suspected to fail at some point driving the camera due to impedance mismatch.

5. Answer Koji's question at Aidan's ELOG .

  3167   Wed Jul 7 12:17:36 2010 RazibUpdatePhase CameraWeekly update

I have completed the following tasks:

1. Find a simplified calibration of the exposure time for the current He-Ne setup. Basically, I triggered the camera to take 20 snapshots with a 20 Hz driving signal at different exposure time beginning from 100 us (microsecond) upto 4000 us with an increment of 200 us.

    Result: The current power allows the camera to have an exposure time of ~500 us before the DC level begans to saturate.

2. Aidan and I did some alignment and connected the AOM and corrected the driving frequency of its PZT to 40 Mhz(which apparently was disconnected which in turn gets the credit of NO beat signal for me until Tuesday 07/06/2010 5:30 PST) .

    Result: I got the beat signal of 1 Hz and 5 Hz. Image follows (the colormap shows the power in arbitrary units).

3. Finished writing my Progress Report 1 .

DC_1Hz_beat_sig.jpgDC_5Hz_beat_sig.jpg

Attachment 1: DC_1Hz_beat_sig.jpg
DC_1Hz_beat_sig.jpg
  3187   Fri Jul 9 12:07:26 2010 RazibUpdatePhase CameraWeekly update

Here are some more details about the current phasecam setup. We are using a He-Ne laser setup

phase_cam_setup_09_08_10.jpg

A crude snap shot of the setup....

mod_setup_(copy)_annotated.jpg

 

We sent light through SM2 (Steering Mirror 2)  to BS1(Beam-Splitter 1) where the laser light is split into two parts, one going to the AOM and the other to the EOM. The EOM adds 40 MHz sidebands to the incoming carrier light after SM3, and the AOM shifts the frequency of the incident light on it to 40.000 005 MHz. The purpose for doing this juggling is to intentionally create a beat signal off the reference beam from the AOM with the sidebands added at the EOM. Note that, we are driving the AOM at 7dBm and the EOM at 13 dBm with 0 (nil) modulation. The two lights are combined at the BS2 and sent off through SM5 to the camera. The CMOS of the camera contains silicon based Micro MT9V022 chip which has a quantum efficiency of 50% at 633 nm. Thus we expected a fairly good response to this He-Ne setup from the camera. 

Using a trigger circuit, we triggered the camera at 20 Hz by sending a 20Hz sinusoidal signal to it. The trigger circuit converts this to a positive square waves. Then I roughly figured out the optimum exposure time for the camera before the DC levels saturates it by writing a code for taking a series of 25 images at different exposure time. I found that 500µs seems to be a reasonable exposure time. So, using this data, I took 20 consecutive images and sent them through a short Fourier Transform segment using Matlab to see the beat signal. Note that the DC component from these processing of the images have some fringe pattern which is due to the ND 2.5 filter that we were using to reduce the light power incident on the camera. The FT method also gave us the presence of the beat signal at the corresponding bin of the FT (for example: for 5Hz beat signal, I got the DC at bin 1 of the FT and 5Hz component at bin 6 as expected). Then I changed the AOM driving frequency to 40.000 001 MHz in order to see a 1 Hz beat signal. The results for both is in my previous post. 

Quote:

I have completed the following tasks:

1. Find a simplified calibration of the exposure time for the current He-Ne setup. Basically, I triggered the camera to take 20 snapshots with a 20 Hz driving signal at different exposure time beginning from 100 us (microsecond) upto 4000 us with an increment of 200 us.

    Result: The current power allows the camera to have an exposure time of ~500 us before the DC level begans to saturate.

2. Aidan and I did some alignment and connected the AOM and corrected the driving frequency of its PZT to 40 Mhz(which apparently was disconnected which in turn gets the credit of NO beat signal for me until Tuesday 07/06/2010 5:30 PST) .

    Result: I got the beat signal of 1 Hz and 5 Hz. Image follows (the colormap shows the power in arbitrary units).

3. Finished writing my Progress Report 1 .

DC_1Hz_beat_sig.jpgDC_5Hz_beat_sig.jpg

 

  3213   Wed Jul 14 10:00:14 2010 josephbUpdatePhase CameraWork near 1Y2 yesterday

Razib and I were attempting to get the output of a photodiode (PD55A in this case) recorded, so that we could independently measure the slow (~1-10 Hz) fluctuations of the light incident on the camera.  This would then allow us to subtract those fluctuations out, letting us get at the camera noise in the case with signal present (as opposed to just a dark noise measurement when we look at the noise with no signal present).

Originally I was thinking of using one empty patch panel BNCs used for PEM channels down by the 1Y7 rack and go through a 110B, although Alberto pointed out he had recently removed some monitoring equipment, which watched the amplitude modulation at various frequencies of the RF distribution (i.e. 33 MHz, etc).  This equipment output a DC voltage proportional to the amplitude of the RF signals.  The associated channel names were C1:IOO-RFAMPD_33MHZ, C1:IOO-RFAMPD_33MHZ_CAL, C1:IOO-RFAMPD_133MHZ, etc.  These are slow channels, so I presume they enter in via the slow computers, probably via pentek (I didn't check that, although in hindsight I probably should have taken the time to find exactly where they enter the system).  The connections them selves were a set of BNCs on the south side, half way up the 1Y2 rack.

We simply chose one, the 33 MHz channel in this case, and connected.  At around this time, the MC did become unlocked, although it looked like it was due to the MC2 watchdog tripping.  The initial theory was we had bumped the Mode Cleaner while looking around for some BNC cables, although from what Rana had to do last night, it probably was the connection.  We were able to restore the watchdog and confirm that the optic started to settle down again.  Unfortunately, I had to leave about 5 minutes later, and didn't do as thorough an investigation as was warranted.

  3215   Wed Jul 14 11:51:48 2010 RazibUpdatePhase CameraWork near 1Y2 yesterday

Quote:

Razib and I were attempting to get the output of a photodiode (PD55A in this case) recorded, so that we could independently measure the slow (~1-10 Hz) fluctuations of the light incident on the camera.  This would then allow us to subtract those fluctuations out, letting us get at the camera noise in the case with signal present (as opposed to just a dark noise measurement when we look at the noise with no signal present).

Originally I was thinking of using one empty patch panel BNCs used for PEM channels down by the 1Y7 rack and go through a 110B, although Alberto pointed out he had recently removed some monitoring equipment, which watched the amplitude modulation at various frequencies of the RF distribution (i.e. 33 MHz, etc).  This equipment output a DC voltage proportional to the amplitude of the RF signals.  The associated channel names were C1:IOO-RFAMPD_33MHZ, C1:IOO-RFAMPD_33MHZ_CAL, C1:IOO-RFAMPD_133MHZ, etc.  These are slow channels, so I presume they enter in via the slow computers, probably via pentek (I didn't check that, although in hindsight I probably should have taken the time to find exactly where they enter the system).  The connections them selves were a set of BNCs on the south side, half way up the 1Y2 rack.

We simply chose one, the 33 MHz channel in this case, and connected.  At around this time, the MC did become unlocked, although it looked like it was due to the MC2 watchdog tripping.  The initial theory was we had bumped the Mode Cleaner while looking around for some BNC cables, although from what Rana had to do last night, it probably was the connection.  We were able to restore the watchdog and confirm that the optic started to settle down again.  Unfortunately, I had to leave about 5 minutes later, and didn't do as thorough an investigation as was warranted.

 Before I left, I disconnected the PD55, so the 33 MHz channel wasn't physically connected to anything!!! Only one end of the wire was connected to the rack while the other was free...

So it wasn't the PD connection that is responsible for MC tripping at the later time...

  3217   Wed Jul 14 12:12:03 2010 RazibSummaryPhase CameraWeekly update

This week I was mainly interested in investigating the noise source at the phase camera. So having this issue in mind, my activities are the following:

1. I worked on producing multiple beat signal (1Hz and 5Hz). Elog entry.

2. I altered the setup so that instead of triggering the camera from the signal generator, we are now triggering it from the beat signal from the reference beam and sideband.

3. I made the nice little aluminium table for all the amplifiers, mixer and splitters to sit at one place instead of floating around.

4. I talked with Aidan and Joe and verified my calculation and extended it to further investigation of the noise source in the setup.

 

Plan for the upcoming week:

1. Measure and calibrate the camera w.r.t the power incident on it.

2. Investigate the noise source.

  3221   Wed Jul 14 18:09:50 2010 josephb, razibUpdatePhase CameraSome cleanup behind 1Y2 rack of phasecamera electronics

We made an attempt at cleaning up the phase camera setup electronics.

We have moved a portion of the electronics onto the SP table (specifically the mixer, splitters, amplifiers, and associated power).  We put away a large number of cables which were unneeded, both BNC and power cables. The Innolight Mephisto power supply and one signal generator are still behind 1Y2 on top of a non-functioning VME crate.  The second VME crate was put along the south arm where two other VME crates already were.  We placed a fair number of BNC cables and power cords back on their cable racks or approriate storage space, so the rats nests of cables has been reduced.

We moved one power strip from plugging in beyind 1Y1, to the far side of the SP table (closer to the 1Y3 rack), and also found and plugged in another power strip (also on the far side of the SP table) and placed this underneath the SP table to be able to power the signal generator and Innolight Mephisto laser (its not plugged in currently, but we'd like to do so next week).

 

  3258   Wed Jul 21 12:20:58 2010 RazibUpdatePhase CameraWeekly update

This past week I have worked on the following:

1. Setting up the infrastructure to do noise analysis: We added a temporary channel on the DAQ to connect to the PD 55 which we are using to take the power measurement. Before that, I connected the PD55 to an oscilloscope and recorded the power.

    phase_cam_setup_21_07_2010.jpg

The power at PD55 as measured using the oscilloscope = 600 µV.

Then I tried to calibrate the channel by sending up a signal from the function generator and measuring up the offset.. However, the channels seems noisy enough, especially due to electronics noise as suggested by the measurements and FFT calculation.

2. I worked on trying to sync the data acquisition of the PD and the CAM. After sometime spent on fiddling with the software method such as taking images at stamped time and then lining them up with the daq timestamps, I found a hardware method as suggested by Aidan. It was putting up a shutter (Uniblitz shutter and driver VMMD1) in the setup. I synced the shutter with the camera for which I had to tear apart the previously made trigger box and add a sync output from the camera (took a while as I also had to make a new cable).

3. I worked (still working) on making a differential amplifier to blow up the signal from the PD.

 

 

 

  3309   Wed Jul 28 13:06:47 2010 RazibUpdatePhase Camera 

Attached are some calculation that I did previously for the phasecamera setup. This shows the nature of the beat signal that we are measuring.

I am also trying to characterize the noise source of the camera also. Following images shows the mean dark noise (with no light on the camera) and the standard deviation for 100 snaps at an exposure time of 500 µs.

mean_100_snaps.pngstd_100_snaps.png

My target now is to measure the response gain of each pixel and how they vary over intensity. I already have a simplified setup on the table and will work on it today. Details will follow at the end of the day.

Attachment 3: phase_cam_calc.pdf
phase_cam_calc.pdf phase_cam_calc.pdf phase_cam_calc.pdf
  3360   Wed Aug 4 16:52:59 2010 Razib, AidanUpdatePhase CameraSideband power measurement (updated)

Aidan and I made some attempt to measure the power of the sidebands so that we can calculate our expected signal strength.

Our setup looks like the following:

Setup_08_04_2010.jpg

 

As light from the laser is split into two at BS1, the transmitted beam has higher power as our BS1 is only coated for 1064nm. We get two reflected beams from BS1, one reflected of the front surface and the other from the back surface. We took the stronger back reflected beam to the EOM driven at 40 MHz (also at 25 MHz at  a later time). The AOM produced a reference beam with 40 .000 005 MHz offset which we recombined with the sidebands obtained from the EOM. The beat produced is sent off to PDA 10CF connected to 4395A spectrum analyzer.

The plots for 40MHz sidebands and 25 MHz sidebands looks like this:

power_40MHz.png

From the above spectra, at 40 MHz sideband regime:

Power of the carrier @ 40 MHz = -39.72 dBm

Power of the sideband @ 80 MHz = -60.39 dBm

 

 

power_25MHz.png

At 25 MHz sideband regime,

Power of the carrier @ 40 MHz = -40.22 dBm

Power of the upper sideband @ 65 MHz = -61.72 dBm

Power of the lower sideband @ 15 MHz = -60.99 dBm

 

Power Measurement:

We made some necessary power measurement using a PD connected to a voltmeter after the EOM and the AOM when the EOM is driven at 40 MHz:

___________________________________________________________

Dark :  0.025 V

AOM on: 4.10 V    (EOM blocked)

EOM : 2.425 V      (AOM blocked)

___________________________________________________________

 From the earlier calculation (ref: Elog entry July 28) the power that we expect to see at the PD is,

P= A_c ^2 + A_r^2 + A_(-sb)^2+ A_sb ^2 +2* A_r* A_sb * cos ( w_(r,sb) t ) ,                         where A_c= carrier;   A_r= reference beam;     A_sb=Upper sideband;    A_(-sb)= Lower sideband,     w_(r,sb) = w_r - w_sb

P = A_c ^2 + A_r^2 + A_(-sb)^2+ A_sb ^2 +2* A_r* A_sb  , letting cos (w_(r,sb) go to 1) is order to approximate the maximum signal

So the signal that we expect to see relative to the DC ( i.e    A_c ^2 + A_r^2 + A_(-sb)^2+ A_sb ^2,    the first four terms of the power equation) is,

Sig = 2* A_r* A_sb    / { A_c ^2 + A_r^2 + A_(-sb)^2+ A_sb ^2 },

Since the modulation index is small, the power in the sideband is very small compared to carrier and the reference beam. So we can ignore the sideband power for the signal expression.

So,

Sig = 2* A_r* A_sb  /  ( A_c ^2 + A_r^2 )

So if we want to maximize this signal w.r.t the reference then,

d (sig)/ d(A_r) = 2 { ( A_c ^2  - A_r^2) *A_sb } / {( A_c^2 + A_r^2)} ^2

Thus, the signal is maximized when,

A_r^2 = A_c^2

 

We adjusted the AOM to be driven at + 7.7 dBM so that the new power at the AOM matched the EOM power, which is 2.397 in the voltmeter.

So the power at both the AOM and the EOM are:

P_AOM = ( V_AOM - V_dark) / (PD responsitivity * Transimpedance gain)

               = ( 2.397 - 0.025 ) / ( 0.45  * 1.5 x 10 ^5 )

               = 3.51 x 10 ^ - 5  W

P_EOM = (V_EOM - V _dark) / (PD responsitivity * Transimpedance gain)

               = ( 2. 425 - .0.025) / ( 0.45 * 1.5 x 10 ^5 )

               = 3.55 x 10^ - 5  W

 

From the spectra of the 40 MHz sideband above, the ratio of the carrier and the sideband amplitude is:  A_c / A_sb = 10.8 .

P_EOM = A_c ^2 + 2 A_sb ^2

Therefore, A_sb = sqrt ( P_EOM / 118.64) = 5.47 x 10^ - 4   V/m

Thus,     A_c = 5.908 x 10^ -3   V/m

and    A_r = sqrt ( P_AOM) = 5.92 x 10 -3    V/m.

 

This measurement can be used to calculate the signal to contrast ratio (SCR) that we expect to see:

SCR = 2 A_r * A_sb  / ( A_c^2  + A_r^2 )  = 0.09

 

Our next step is to measure the actual signal to constrast ratio as seen by the camera. Details of that will be posted soon.

  3411   Thu Aug 12 16:52:02 2010 RazibUpdatePhase CameraSideband power measurement (updated)

I made some measurement of the SCR (signal to contrast ratio) from the signal from the EOM and the AOM.

The recipe for that was:

1. Trigger the camera at 20 Hz (from function generator).

2. Take a series of 20 images.

3. Do FFT to take out the DC component.

4. Extract the beat signal out of the FFT'd data.

5. Block the EOM.

6. Take another set of images of the AOM beam.

7. Take more(!) images, but this time of the background (blocking both EOM and AOM).

 

So the SCR is calculated by the ratio of the FFT'd DC and the 5 Hz signal. Using the CCD, I obtained the SCR to be 0.075 ± 0.01. Previously, we expected our SCR to be 0.09 as in the previous e-log entry.

The plot for that is:

SCR.jpg

 After measuring the SCR, I also measured the amplitude of the sideband and made an amplitude profile of the 40 MHz sideband.

The amplitude measurement is done as follows:

We know that the our 5 Hz signal consists of,

Sig = A_r * A_sb    where A_r = amplitude of the reference beam, A_sb= amplitude of the sideband

So, A_sb = Sig / A_r .

But,  A_r = sqrt ( P_AOM - Background),

Thus  A_sb = Sig / sqrt( P_AOM - Background) .

So the amplitude profile is done by taking the 5 Hz beat signal and dividing by the square root of the AOM beam minus the background light.

The plots looks like this:

DC_sig_sideband_profile.jpg

The solo sideband profile looks like this:

sideband_profile.jpg

Next we plan to trigger the camera with a 1 KHz signal and take snaps at n* T/4 (where n=0,1,2,3) of the period of the beat signal. So the plan is to trigger the camera at the point where the red dots appear in following cartoon.

sine_trig.jpg

Some more details of this setup will be posted later.

  

Quote:
 

 

Attachment 4: sine_trig.jpg
sine_trig.jpg
  3412   Thu Aug 12 17:10:07 2010 KojiUpdatePhase CameraSideband power measurement (updated)

This sounds very relieving although this could be a lower bound of the number.
Why didn't you use the output on the PD which just give us the direct observation of your so-called SCR.

Ed: I meant time series of the PD output

Quote:

So the SCR is calculated by the ratio of the FFT'd DC and the 5 Hz signal. Using the CCD, I obtained the SCR to be 0.075 ± 0.01. Previously, we expected our SCR to be 0.09 as in the previous e-log entry. 

 

  3413   Thu Aug 12 17:28:28 2010 RazibUpdatePhase CameraSideband power measurement (updated)

Quote:

This sounds very relieving although this could be a lower bound of the number.
Why didn't you use the output on the PD which just give us the direct observation of your so-called SCR.

Quote:

So the SCR is calculated by the ratio of the FFT'd DC and the 5 Hz signal. Using the CCD, I obtained the SCR to be 0.075 ± 0.01. Previously, we expected our SCR to be 0.09 as in the previous e-log entry. 

 

 The SCR was at first measured using the output of the PD. That was exactly from where we got our 0.09 (previous elog entry). The second measurement was from the CCD.

  50   Thu Nov 1 19:53:02 2007 Andrey RodionovBureaucracyPhotosTobin's picture
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  51   Thu Nov 1 19:53:34 2007 Andrey RodionovBureaucracyPhotosRobert's photo
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  52   Thu Nov 1 19:54:22 2007 Andrey RodionovBureaucracyPhotosRana's photo
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  53   Thu Nov 1 19:55:03 2007 Andrey RodionovBureaucracyPhotosAndrey's photo
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  54   Thu Nov 1 19:55:59 2007 Andrey RodionovBureaucracyPhotosAndrey, Tobin, Robert - photo
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  55   Thu Nov 1 19:58:07 2007 Andrey RodionovBureaucracyPhotosSteve and Tobin's picture
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  56   Thu Nov 1 20:03:00 2007 Andrey RodionovSummaryPhotosProcedure "Drop and Drag" in pictures
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  210   Fri Dec 21 20:32:25 2007 tobinUpdatePhotosGigE camera
I couldn't resist any longer: I plugged in the Prosilica GC 750 GigE camera and took it for a spin. This is the little CMOS camera which sends out video over gigabit ethernet.

There were no difficulties at all in getting it running. I just plugged in the power, plugged in ethernet, and put on a lens from Steve's collection. I downloaded the "Sample Viewer" from the Prosilica website and it worked immediately.

It turns out that "Kirk's" computer has not only a gigabit ethernet card, but a little gigabit ethernet switch. I plugged the camera into this switch. The frame rate is amazing. With the camera under fluorescent lights I thought I saw some wacky automatic gain control, but I think this ~10Hz flicker is aliasing of the 60 Hz room lighting.

I put the camera on the PSL table briefly and tried viewing the image from a laptop over the (54mbs) wireless network. This didn't work so well: you could get a couple frames out of the camera, but then the client software would complain that it had lost communications. It appeared that scattered 1064nm light did show up brightly on the camera image. There is a green ethernet cable currently stashed on the roof of the PSL that appears unused. We can try mounting the gigE CMOS cable in place of one of the CCD video cameras.

I did not try the Linux software.

The camera is currently set up at Kirk's desk, using the cool little tripod Rana got from CyberGuys.

This camera looks very promising! Also, in the test image attached below, a very unusual condition has been documented.
Attachment 1: robs_desk.png
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  243   Wed Jan 16 19:57:49 2008 tobinConfigurationPhotosISCT_EX
Here's a photo of the ISCT_EX table, for the purpose of planning our auxiliary laser arm locking scheme. Note the (undumped!) beam from the beamsplitter before QPDX (the leftmost gold-colored box); perhaps we could inject there.
Attachment 1: trx-annotated-small.jpg
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ELOG V3.1.3-