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  235   Thu Aug 20 01:35:01 2015 KojiElectronicsGeneralOMC DCPD in-vacuum electronics chain test

We wanted to know the  transimpedance of the OMC DCPD at high frequency (1M~10M).
For this purpose, the OMC DCPD chain was built at the 40m. The measurement setup is shown in Attachment 1.

- As the preamp box has the differential output (pin1 and pin6 of the last DB9), pomona clips were used to measure the transfer functions for the pos and neg outputs individually.

- In order to calibrate the measurements into transimpedances, New Focus 1611 is used. The output of this PD is AC coupled below 30kHz.
This cutoff was calibrated using another broadband PD (Thorlabs PDA255 ~50MHz).

Result: Attachment 2
- Up to 1MHz, the transimpedance matched well with the expected AF transfer function. At 1MHz the transimpedance is 400.

- Above 1MHz, sharp cut off at 3MHz was found. This is consistent with the openloop TF of LT1128.

 

Attachment 1: OMC_DCPD_Chain.pdf
OMC_DCPD_Chain.pdf
Attachment 2: OMC_DCPD_Transimpedance.pdf
OMC_DCPD_Transimpedance.pdf
  234   Mon Aug 10 12:09:49 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151

Still suffering from a power supply issue!

I have been tracking the issues I'm having with the RF AM detector board.

I found that the -5V test point did not show -5V but ~+5V! It seemed that this pin was not connected to -5V but was passive.

I removed the RF AM detector board and exposed the power board again. Pin 11 of P3 interboard connector indeed was not connected to TP12 (-5V). What the hell?

As seen in the attached photo, the PCB pattern for the Pin 11 is missing at the label "!?" and not driven. I soldered a piece of wire there and now Pin11 is at -5V.


This fix actually changed several things. Now the bias setting by the rotary switches works.

Setting BIAS1
 [dBm]   [V]

   0    0.585
   2    0.720
   4    0.897
   6    1.12
   8    1.42
  10    1.79
  12    2.25
  14    2.84
  16    3.60
  18    4.56
  20    5.75
  22    7.37

This allows me to elliminate the saturation of MON1 of the first RF AM detector. I can go ahead to the next step for the first channel.

Now the bias feedback of the second detector is also behaving better. Now TP2 is railing.

Still MON2 is saturated. So, the behavior of the peak detectors needs to be reviewed.

Attachment 1: IMG_20150809_215628585_HDR.jpg
IMG_20150809_215628585_HDR.jpg
  233   Mon Aug 10 11:57:17 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151

Spending some days to figure out how to program CPLD (Xilinx CoolRunner II XC2C384).

I learned that the JTAG cable which Daniel sent to me (Altium JTAG USB adapter) was not compatible with Xilinx ISE's iMPACT.

I need to use Altium to program the CPLD. However I'm stuck there. Altium recognizes the JTAG cable but does not see CPLD. (Attachment 1)

Upon the trials, I followed the instruction on awiki as Daniel suggested.
http://here https://awiki.ligo-wa.caltech.edu/aLIGO/TimingFpgaCode

Altium version is 15.1. Xilinx ISE Version is 14.7

Attachment 1: screen_shot.png
screen_shot.png
  232   Mon Aug 10 11:39:40 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151

Entry for Aug 6th, 2015

I faced with difficulties to operate the RF AM detectors.

I tried to operate the RF AM detector. In short I could not as I could not remove the saturation of the MON outputs, no matter how jiggle the power select rotary switches. The input power was 10~15dBm.

D0900761 Rev.A
https://dcc.ligo.org/LIGO-D0900761-v1

I've measured the bias voltage at TP1. Is the bias such high? And does it show this inversion of the slope at high dBm settings?

Setting Vbias
 [dBm]   [V]

   0    21.4
   2    21.0
   4    20.5
   6    19.8
   8    18.8
  10    17.7
  12    16.3
  14    14.2
  16    11.9
  18    10.6
  20    11.8
  22    15.0


The SURF report (https://dcc.ligo.org/LIGO-T1000574) shows monotonic dependence of Vbias from 0.6V to 10V (That is supposed to be the half of the voltage at TP1). 
I wonder I need to reprogram FPGA?

But if this is the issue, the second detector should still work as it has the internal loop to adjust the bias by itself.
TP3 (Page 1 of D0900761 Rev.A) was railed. But still MON2 was saturated.
I didn't see TP2 was also railed. It was ~1V (not sure any more about the polarity). But TP2 should also railed.

Needs further investigation

  231   Mon Aug 10 02:11:47 2015 KojiElectronicsAM Stabilized EOM DriverRF AM Measurement Unit E1500151

This is an entry for the work on Aug 3rd.

LIGO DCC E1500151

Power supply check

- Removed the RF AM detector board and exposed the D0900848 power board. The board revision is Rev. A.

- The power supply voltage of +30.2V and -30.5V were connected as +/-31V supplies. These were the maximum I could produce with the bench power supply I had. +17.2V and -17.1V were supplied as +/-17V supplies.

- Voltage reference: The reference voltages were not +/-10V but +/-17V. The cause was tracked down to the voltage reference chip LT1021-10. It was found that the chip was mechanically destroyed (Attachment 1, the legs were cut by me) and unluckily producing +17V. The chip was removed from the board. Since I didn't have any spare LT1021-10, a 8pin DIP socket and an AD587 was used instead. Indeed AD587 has similar performance or even better in some aspects. This fixed the reference voltage.

- -5V supply: After the fix of the reference voltage, I still did not have correct the output voltage of -5V at TP12. It was found that the backpanel had some mechanical stress and caused a leg of the current boost transister cut and a peeling of the PCB pattern on the component lalyer (Attachment 2). I could find some spare of the transister at the 40m. The transister was replaced, and the pattern was fixed by a wire. This fixed the DC values of the power supply voltages. In fact, +/-24V pins had +/-23.7V. But this was as expected. (1+2.74k/2k)*10V = 23.7V .

- VREFP Oscillation: Similarly to the EOM/AOM driver power supply board (http://nodus.ligo.caltech.edu:8080/OMC_Lab/225), the buffer stage for the +10V has an oscillation at 762kHz with 400mVpp at VREFP. This was fixed by replacing C20 (100pF) with 1.2nF. The cap of 680pF was tried at first, but this was not enough to completely elliminate the oscilation.

- VREFN Oscillation: Then, similarly to the EOM/AOM driver power supply board (http://nodus.ligo.caltech.edu:8080/OMC_Lab/225), the amplifier and buffer stage for the -10V has an oscillation at 18MHz with 60mVpp at VREFN. This was fixed by soldering 100pF between pin6 and pin7 of U6.

- Voltage "OK" signal: Checked the voltage of pin5 of U1 and U4 (they are connected). Nominally the OK voltage had +2.78V. The OK voltage turned to "Low (~0V)" when:
The +31V were lowered below +27.5V.
The +31V were lowered below -25.2V.
The +17V were lowered below +15.2V.
The +17V were lowered below -15.4V.

- Current draw: The voltage and current supply on the bench top supplies are listed below

+30.2V 0.09A, -30.5V 0.08A, +17.2V 0.21A, -17.1V 0.10A

- Testpoint voltages:

TP12(-5V) -5.00V
TP11(-15) -14.99V
TP10(-24V) -23.69V
TP9(-10V) -9.99V
TP5(-17V) -17.15V
TP6(-31V) -30.69

TP2(+31V) +30.37V
TP3(+17V) +17.24V
TP8(+10V) +10.00V
TP16(+28V) +28.00V
TP13(+24V) +23.70V
TP14(+15V) +15.00V
TP15(+5V) +5.00V

 

Attachment 1: IMG_20150803_223403975.jpg
IMG_20150803_223403975.jpg
Attachment 2: IMG_20150803_221210816_HDR.jpg
IMG_20150803_221210816_HDR.jpg
Attachment 3: IMG_20150803_223420267.jpg
IMG_20150803_223420267.jpg
  230   Tue Jul 28 18:36:50 2015 KojiElectronicsAM Stabilized EOM DriverRF test of the EOM/AOM Driver S1500117

Final Test Result of S1500117: https://dcc.ligo.org/LIGO-S1500117


After some staring the schematic and checking some TFs, I found that the DAQ channels for MON2 have a mistake in the circuit.
Differential driver U14 and U15 of D0900848 are intended to have the gain of +10 and -10 for the pos and neg outputs.
However, the positive output has the gain of +1.

Daniel suggested to shift R66 and R68 by one pad, replace with them by ~5.5K and add a small wire from the now "in air" pad to
the GND near pad 4.

The actual modification can be seen on Attachment 1. The resulting gain was +10.1 as the resisters of 5.49k were used.

The resulting transfer function is found in the Attachment 2. ow the nominal magnitude is ~x20.

You may wonder why the transfer function for MON1 is noisy and lower at low freq (f<1kHz). This is because the input noise of the FFT analizer
contributed to the BNC MON1 signal. High frequency part dominated the RMS of the signal and the FFT analyzer could not have proper range
for the floor noise. The actual voltage noise comparison between the BNC and DAQ signals for MON1 and MON2 can be found in Attachment 3.
 

Attachment 1: IMG_20150727_214536773_HDR.jpg
IMG_20150727_214536773_HDR.jpg
Attachment 2: EOM_Driver_DAQ_TF_test.pdf
EOM_Driver_DAQ_TF_test.pdf
Attachment 3: EOM_Driver_Mon_PSD.pdf
EOM_Driver_Mon_PSD.pdf
  229   Sat Jul 25 17:24:11 2015 KojiElectronicsAM Stabilized EOM DriverRF test of the EOM/AOM Driver S1500117

(Calibration for Attachment 5 corrected Aug 27, 2015)


Now the test procedure fo the unit is written in the document https://dcc.ligo.org/LIGO-T1500404

And the test result of the first unit (S1500117) has also been uploaded to DCC https://dcc.ligo.org/LIGO-S1500117

Here are some supplimental information with plots

Attachment 1: OLTF of the AM amplitude stabilization servo.

Attachment 2: CLTF/OLTF of the 2nd AM detector self bias adj servo

The secondary RF AM detector provides us the out-of-loop measurement. The secondary loop has an internal control loop to adjust the DC bias.
This loop supresses the RF AM error signal below the control bandwidth. This has been tested by injecting the random noise to the exc and taking
the transfer function between the primary RF AM detector error (MON1) and the secondary one (MON2).

Then the closed loop TF was converted to open loop TF to see where the UGF is. The UGF is 1Hz and the phase margin is 60deg.

Above 10Hz, the residual control gain is <3%. Therefore we practically don't need any compensation of MON2 output above 10Hz.

Attachment 3: Comparison between the power setting and the output power

Attachment 4: Raw power spectra of the monitor channels

Attachment 5: Calibrated in-loop and out-of-loop AM noise spectra

Attachment 6: TFs between BNC monitor ports and DAQ differential signals

BIAS2 and CTRL look just fine. BIAS2 has a gain of two due to the differential output. The TF for CTRL has a HPF shape, but in fact the DC gain is two.
This frequency response comesfro that the actual CTRLis taken after the final stage that has LPF feature while the CTRL DAQ was taken before this final stage.

MON1 and MON2 have some riddle. I could not justify why they have the gain of 10 instead of 20. I looked into the issue (next entry)

Attachment 7: TF between the signals for the CTRL monitor (main unit) and the CTRL monitor on the remote control test rig

The CTRL monitor for the test rig is taken from the CTRL SLOW signal. There fore there is a LPF feature together with the HPF feature described above.
This TF can be used as a reference.

 

Attachment 1: EOM_Driver_AM_servo_OLTF.pdf
EOM_Driver_AM_servo_OLTF.pdf
Attachment 2: EOM_Driver_2ndAMdet_CLOLTF.pdf
EOM_Driver_2ndAMdet_CLOLTF.pdf
Attachment 3: EOM_Driver_Output_Power.pdf
EOM_Driver_Output_Power.pdf
Attachment 4: EOM_Driver_Mon_PSD.pdf
EOM_Driver_Mon_PSD.pdf
Attachment 5: EOM_Driver_AM_PSD.pdf
EOM_Driver_AM_PSD.pdf
Attachment 6: EOM_Driver_DAQ_TF_test.pdf
EOM_Driver_DAQ_TF_test.pdf
Attachment 7: EOM_Driver_CTRL_TESTRIG_TF.pdf
EOM_Driver_CTRL_TESTRIG_TF.pdf
  228   Wed Jul 22 10:15:14 2015 KojiElectronicsAM Stabilized EOM DriverRF test of the EOM/AOM Driver S1500117

7) Make sure the on/off RF button works,
=> OK

8) Make sure the power output doesn't oscillate,

Connect the RF output to an oscilloscope (50Ohm)
=> RF output: there is no obvious oscillation

Connect the TP1 connector to an oscilloscope
=> check the oscillation with an oscilloscope and SR785 => OK

Connect the CTRL connector to an oscilloscope
=> check the oscillation with an oscilloscope and SR785 => OK

9) EXC check
Connect a function generator to the exc port.
Set the FG output to 1kHz 2Vpk. Check the signal TP1
Turn off the exc switch -> no output
Turn on the exc switch -> nominally 200mVpk

=> OK

10) Openloop transfer function

Connect SR785 FG->EXC TP2->CHA TP1->CHB
EXC 300mV 100Hz-100kHz 200 line

Network Analyzer (AG4395A)
EXC 0dBm TP1->CHA TP2->CHB, measure A/B
801 line
CHA: 0dBatt CHB: 0dBatt
1kHz~2MHz
UGF 133kHz, phase -133.19deg = PM 47deg

11) Calibrate the output with the trimmer on the front panel

13dB setting -> 12.89dBm (maximum setting)

12) Check MON, BIAS and CTRL outputs,
CTRL:    2.95V
MON(L):    6.5mV
BIAS(L):    1.81V
MON(R):    10.7mV
BIAS(R):    1.85V

13) Output check
4+0dB    3.99dBm
6    5.89
8    7.87
10    9.87
12    11.88
14    13.89
16    15.89
18    17.92
20    19.94
22    21.95
24    24.00
26    26.06

4dB+
0.0    3.99
0.2    4.17
0.4    4.36
0.6    4.56
0.8    4.75
1.0    4.94
1.2    5.13
1.4    5.32
1.6    5.53
1.8    5.73
2.0    5.92
2.2    6.10

16dB+
0.0    15.82
0.2    16.11
0.4    16.31
0.6    16.51
0.8    16.72
1.0    16.92
1.2    17.12
1.4    17.32
1.6    17.53
1.8    17.72
2.0    17.92
2.2    18.13

26dB+
0.0    26.06
0.2    26.27
0.4    26.46
0.6    26.58
0.8    26.68
1.0    26.69
1.2    26.70
1.4    3.98
1.6    3.99
1.8    3.99
2.0    3.99
2.2    3.99

 

 

 

  227   Wed Jul 22 09:43:01 2015 KojiElectronicsAM Stabilized EOM DriverPower supply test of the EOM/AOM Driver

Serial Number of the unit: S1500117
Tester: Koji Arai
Test Date: Jul 22, 2015

1) Verify the proper current draw with the output switch off:

+24 Volt current: 0.08 A Nom.
-24 Volt current: 0.07 A Nom.
+18 Volt current: 0.29 A Nom.
-18 Volt current: 0.24 A Nom.

2) Verify the proper current draw with the output switch on:
+24 Volt current: 0.53 A Nom.
-24 Volt current: 0.07 A Nom.
+18 Volt current: 0.21 A Nom.
-18  Volt current: 0.26 A Nom.

3) Verify the internal supply voltages:

All look good.

TP13 -5.001V
TP12 -15.00
TP11 -21.05
TP10 -10.00
TP5  -18.19
TP6  -24.22
TP2  +24.15
TP3  +18.22
TP9  + 9.99
TP17 +24.15
TP14 +21.04
TP15 +15.00
TP16 + 4.998

4) Verify supply OK logic:
All look good. This required re-disassembling of the PCBs...

Check then pin 5 on U1 (connected to R11) and U4 (connected to R23):

U1 3.68V (=Logic high)
U4 3.68V (=Logic high)

5) Verify the relays for the power supply sequencing: OK

Turn off +/-24 V. Confirm Pin 5 of K1 and K2 are not energized to +/-18V. => OK
Turn on +/-24 V again. Confirm Pin 5 of K1 and K2 are now energized to +/-18V. => OK

6) Verify noise levels of the internal power supply voltages:

TP13 (- 5V) 13nV/rtHz@140Hz
TP12 (-15V) 22
nV/rtHz@140Hz
TP11 (-21V) 32
nV/rtHz@140Hz
TP10 (-10V) 16nV/rtHz@140Hz
TP9  (+10V)  9
nV/rtHz@140Hz
TP14 (+21V) 21nV/rtHz@140Hz
TP15 (+15V) 13nV/rtHz@140Hz
TP16 (+ 5V) 11nV/rtHz@140Hz

 

Note that the input noise of SR785 is 9~10nV/rtHz@140Hz with -50dBbpk input (AC)

 

  226   Tue Jul 21 20:20:12 2015 KojiGeneralGeneralItem lending

Kate (ATF)

- 4ch color oscilloscope (Tektronix)

- Chopper controller

- Chopper with a rotating disk

  225   Sat Jul 18 11:37:21 2015 KojiElectronicsAM Stabilized EOM DriverD0900848 power board ~ oscillation issue solved

Power Supply Board D0900848 was oscillating. Here is the procedure how the issue was fixed.

PCB schematic: LIGO DCC D0900848

0. Extracting the power board.

The top lid and the front panel were removed. Top two modules were removed from the inter-board connection.
Some of the SMA cables were necessary to be removed to allow me to access to the botttom power board.

1. D1~D4 protection diodes

Daniel asked me to remove D1, D2, D3, D4 as the power supply sequence is controlled by the relays.
This was done.

2. Power supply oscillation
Since the power supply systems are entagnled, the oscillation of the transister boosted amps had to be checked one by one.

2.1 VREFP (U5)

First of all, the buffering stage of the positive voltage reference (U5) was oscillating. Attachment 1 is the observed voltage at "VREFP" at D13.
The oscillation was at 580kHz with 400mVpp. This was solved by replacing C20 with 1.2nF. (0805 SMD Cap)

2.2 VREFN (U6)

Then the buffering stage of the negative voltage reference (U6) was checked. Attachment 2 is the observed voltage at "VREFN" at D16.
The oscillation was at 26MHz with 400mVpp. This seemed to have a different mechanism from the U5 oscillation. This oscillation frequency is
higher than the GBW of OP27. So there must be some spurious path to the transister stage. This amplifier stage is a bit unique.
The input is VREFP, but the positive supply is also VREFP. And the feedback path between R31 and C24 is very long. I was afraid that this oscillation
was caused by some combination of L and stray C by the long feedback path and the output to power VREFP coupling, although I could not reproduce
the oscillation on LTSpice. 

After some struggles, adding a 100pF cap between the output of U6 op27 (PIN6) and VREFP (PIN7) stopped the oscillation.
I think this changes the loop function and fullfills the stability condition. I confirmed by a LTSpice model that additional cap does not
screw up the original function of the stage at audio frequencies when everything is functioning as designed.

2.3 Positive supply systems (U10, U11, U12)

Even after fixing the oscillations of U5 and U6, I kept observing the oscllative component of ~600kHz at U10 (+21V), U11 (+15V), and U12 (+5V) stages.
Among them, U11 had the biggest oscillation of 400mVpp at the opamp out (Attachment 3). The other two had small oscillation like 20mVpp at the opamp outputs.
The solution was the same as 2.1. C50, C51, and C52 were replaced to 1.2nF. After the modification I still had the 600kHz component with 2mVpp.
I wanted to check other channels and come back to this.

2.3 Negative supply systems (U7, U8, U9)

Similarly the outputs of U7, U8, and U9 had the oscillation at 600kHz with 40~80mVpp. Once C35, C36, and C37 were replaced with 1.2nF,
I no longer could see any 600kHz anywhere, including U10~U12.

2.4 -24V system (U13)

Last modification was U13. It had a noise of 50mVpp due to piled-up random pulses (Attachment 4). I just tried to replace C63 with 1.2nF
and remove a soldering jumber of W1
. There still looks random glitches there. But it's no longer the round shaped pulses but a sharp gliches
and the amplitude is 20mV each (Attachment 5). In fact, later I noticed that Q9 is not stuffed and W2 is closed. This means that the +24V external supply is
directly connected to +24AMP. Therefore U13 has no effect to the 24V suppy system.

3. Restoring all connections / final check of the voltages

Restore the middle and top PCBs to the intra-PCB connector board. Attach the front panel. Restore the SMA connections.

The missing soldering of the SMA cable (reported in the previous entry) was soldered.

Once all the circuits are connected again, the power supply voltages were checked again. There was no sign of oscillation.

All the above modifications are depicted in Attachment 6.

Attachment 1: IMG_20150715_215516907.jpg
IMG_20150715_215516907.jpg
Attachment 2: IMG_20150715_215706039.jpg
IMG_20150715_215706039.jpg
Attachment 3: IMG_20150714_203246414.jpg
IMG_20150714_203246414.jpg
Attachment 4: IMG_20150717_215132303.jpg
IMG_20150717_215132303.jpg
Attachment 5: IMG_20150717_220919527.jpg
IMG_20150717_220919527.jpg
Attachment 6: D0900848_modifications.jpg
D0900848_modifications.jpg
  224   Wed Jul 15 22:23:17 2015 KojiElectronicsAM Stabilized EOM DriverE1400445 first look

This is not an OMC related and even not happening in the OMC lab (happening at the 40m), but I needed somewhere to elog...


E1400445 first look

LIGO DCC E1400445

Attachment 1: Record of the original state

Attachment 2: Found one of the SMA cable has no shield soldering

Attachment 1: IMG_20150714_195534852.jpg
IMG_20150714_195534852.jpg
Attachment 2: IMG_20150714_195227746_HDR.jpg
IMG_20150714_195227746_HDR.jpg
  223   Wed Feb 18 21:51:23 2015 KojiGeneralGeneralNotes on OMC Transportation Fixtures & Pelican

LLO has one empty OMC transportation fixture.

LHO has one empty OMC transportation fixture.

LHO has one OMC transportation fixture with 3IFO OMC in it.

LHO has the Pelican trunk for the OMC transportation. Last time it was in the lab next to the optics lab.

  222   Wed Feb 4 20:07:24 2015 KojiGeneralGeneralItem lending

Shipment to MIT (L. Barsotti, J. Miller)

1. UV Illuminator (LESCO Super Spot MK III)

2. UV Power meter (American Ultraviolet AIB1001) Caltech property C30140

3. UV protection face shield (VWR UVC-803) Qty.2 Caltech property C30141/C30142

4. UV Fiber Optic Light Guide (American Ultraviolet OLB1081) C30143

All returned: Aug 30, 2016

Attachment 1: C30140_1.JPG
C30140_1.JPG
Attachment 2: C30140_2.JPG
C30140_2.JPG
Attachment 3: C30141.JPG
C30141.JPG
Attachment 4: C30142.JPG
C30142.JPG
Attachment 5: C30143.JPG
C30143.JPG
  221   Tue Feb 3 18:23:49 2015 KojiGeneralGeneralItem lending

- The laser was removed and shipped to LHO today.

- UV illuminator / fused silica fiber light guide / UV power meter / UV face shield (Qty 2) will be shipped to MIT.
They are CIT properties except for the illuminator.

Quote:

Gabriele:

PZT HV Amp

Evan:
HP signal generator (990MHz) (prev. setting 32.7MHz / +3dBm)
Black glass beam dump

Dmass:

LB1005 Oct 24.

Quote:

Tara: Laser Safety goggle -> Returned

Evan:
HP signal generator (990MHz) (prev. setting 32.7MHz / +3dBm)
Black glass beam dump

Dmass:

LB1005 Oct 24.

 

 

  220   Fri Jan 30 19:31:08 2015 KojiGeneralGeneralItem lending

Gabriele:

PZT HV Amp

Evan:
HP signal generator (990MHz) (prev. setting 32.7MHz / +3dBm)Returned March 23, 2016
Black glass beam dump

Dmass:

LB1005 Oct 24. This unit is permanently gone to Cryo lab. Acquired a new unit. Aug, 2016.

Quote:

Tara: Laser Safety goggle -> Returned

Evan:
HP signal generator (990MHz) (prev. setting 32.7MHz / +3dBm)
Black glass beam dump

Dmass:

LB1005 Oct 24.

 

  219   Sat Jan 17 11:40:04 2015 KojiGeneralGeneral3rd OMC completed

Jan 15, 2015 3rd OMC completed

The face caps of the DCPD/QPD cables were installed (Helicoils inserted)
PD7&10 swapped with PD11(for DCPD T) and PD12(DCPD R).
Firct Contact coating removed

Note on the 3rd OMC

Before the 3rdOMC is actually used,

- First Contact should be applied again for preventing contamination during the installation

- DCPD glass windows should be removed

  218   Tue Sep 9 20:59:19 2014 KojiMechanicsCharacterizationStructural mode analysis for the PZT mirror

Structural analysis of the PZT mirror with COMSOL.

Inline figures: Eigenmodes which involves large motion of the tombstone. In deed 10kHz mode is not the resonance of the PZT-mirror joint, but the resonance of the tombstone.

Attached PDF: Simulated transfer function of the PZT actuation. In order to simulate the PZT motion, boundary loads on the two sides of the PZT were applied with opposite signs.
10kHz peak appears as the resonance of the tombstone dominates the mirror motion. At 12kHz, the PZT extension and the backaction of the tombstone cancells each other and
the net displacement of the mirror becomes zero.

PZT_10.0kHz.png PZT_14.6kHz.png PZT_18.0kHz.png

PZT_22.5kHz.png PZT_29.7kHz.png

Attachment 1: PZT_response_FEA.pdf
PZT_response_FEA.pdf
  217   Wed Aug 27 23:13:13 2014 KojiOpticsCharacterizationCollection of the power budgetting info

L1 OMC Cavity power budget

H1 OMC Cavity power budget

3IFO OMC Cavity power budget

  216   Tue Aug 5 13:03:25 2014 KojiGeneralGeneralMissing cable components

DCPD Connector Face: Qty2 https://dcc.ligo.org/LIGO-D1201276
QPD Connector Face: Qty2 https://dcc.ligo.org/LIGO-D1201282

PD faster: 92210A07 Qty 4: MCMASTER #2-56 x .25 FHCS

Spare DCPD

  215   Mon Aug 4 18:59:50 2014 KojiGeneralGeneralA memorandom

On breadboarfd cabling for 3IFO OMC

D1300371 - S1301806
D1300372 - S1301808
D1300374 - S1301813
D1300375 - S1301815

  214   Thu Jul 31 15:07:53 2014 KojiGeneralGeneralItem lending

Tara: Laser Safety goggle -> Returned

Evan:
HP signal generator (990MHz) (prev. setting 32.7MHz / +3dBm)
Black glass beam dump

Dmass:

LB1005 Oct 24.

  213   Mon Jul 21 01:02:43 2014 KojiMechanicsCharacterizationSome structual mode analysis

Prisms

Fundamental: 12.3kHz Secondary: 16.9kHz

PRISM_12_3kHz.png PRISM_16_9kHz.png

DCPDs

Fundamental: 2.9kHz Secondary: 4.1kHz

DCPD_2_9kHz.png DCPD_4_1kHz.png

QPDs

Fundamental: 5.6kHz Secondary: 8.2kHz

QPD_6_0kHz.png QPD_8_2kHz.png

  212   Sun Jul 20 17:20:39 2014 KojiGeneralGeneralThe 3rd (LIO) OMC was shipped out to LHO

The 3rd (LIO) OMC was shipped out to LHO on Friday (Jul 18) Morning.

At LHO

- All of the on-breadboard cables should be attached and tied down.

- Peel First Contact paint and pack the OMC for storage.

 

  211   Sun Jul 20 17:19:50 2014 KojiMechanicsCharacterizationI1OMC vibration test ~ 2nd round

Improved vibration measurement of the OMC

Improvement

- Added some vibration isolation. Four 1/2" rubber legs were added between the OMC bread board and the transport fixture (via Al foils).
  In order to keep the beam height same, 1/2" pedestal legs were removed.

- The HEPA filter at the OMC side was stopped to reduce the excitation of the breadboard. It was confirmed that the particle level for 0.3um
  was still zero only with the other HEPA filter.


Method

- Same measurement method as the previous entry was used.

Results

Breadboard

- In this new setup, we could expect that the resonant frequency of the body modes were close to the free resonances, and thus the Q is higher.
  Noise is much more reduced and it is clear that the resonance seen 1.1kHz is definitely associated with the body mode of the breadboard (red curve).

  As a confirmation, some metal objects were placed on the breadboard as tried before. This indeed reduced the resonant frequency (blue curve).

I1OMC_vibration_test_Breadboard.pngI1OMC_vibration_test_Breadboard_HiRes.png

DCPD / QPD

- Vibration on the DCPDs and QPDs mainly excited the modes above 2~3kHz.
  In order to check if they are coming from the housing, we should run FEA models.

- Some excitation of the breadboard mode at 1.1kHz was also seen.

I1OMC_vibration_test_DCPD.pngI1OMC_vibration_test_QPD.png

CM1/CM2 (PZT mirrors)

- Baseically excitation was dominated by the PZT mode at 10kHz. Some spourious resonances are seen at 4~5kHz but I believe this is associated with the weight placed on the excitation PZT.

I1OMC_vibration_test_CM.png

FM1/FM2 and peripheral prism mirrors (BSs and SMs)

- The modes of the FMs are seen ~8k or 12kHz. I believe they are lowered by the weight for the measurement. In any case, the mode frequency is quite high compared to our frequency region of interest.

- As the prism resonance is quite high, the excitation is directly transmitted to the breadboard. Therefore the excitation of the non-cavity caused similar effect to the excitation on the breadboard.
  In fact what we can see from the plot is excitation of the 1.1kHz body mode and many high frequency resonances.

I1OMC_vibration_test_FM.pngI1OMC_vibration_test_Prism.png

Beam dumps

- This is also similar to the case of the peripheral mirrors.

I1OMC_vibration_test_BD.png

Attachment 1: I1OMC_vibration_test.pdf
I1OMC_vibration_test.pdf I1OMC_vibration_test.pdf I1OMC_vibration_test.pdf I1OMC_vibration_test.pdf I1OMC_vibration_test.pdf I1OMC_vibration_test.pdf I1OMC_vibration_test.pdf I1OMC_vibration_test.pdf
  210   Thu Jul 17 02:19:20 2014 KojiMechanicsCharacterizationI1OMC vibration test

Summary

- The breadboard has a resonance at 1.2kHz. The resonant freq may be chagned depending on the additional mass and the boundary condition.

- There is no forest of resonances at around 1kHz. A couple of resonances It mainly starts at 5kHz.

- The PZT mirrors (CM1/CM2) have the resonance at 10kHz as I saw in the past PZT test.


Motivation

- Zach's LLO OMC characterization revealed that the OMC length signals have forest of spikes at 400-500Hz and 1kHz regions.

- He tried to excite these peaks assuming they were coming from mechanical systems. It was hard to excite with the OMC PZT,
but actuating the OMCS slightly excited them. (This entry)

Because the OMC length control loop can't suppress these peaks due to their high frequency and high amplitude, they limit
the OMC residual RMS motion. This may cause the coupling of the OMC length noise into the intensity of the transmitted light.
We want to eventually suppress or eliminate these peaks.

By this vibration test we want to:

- confirm whether the peaks are coming from the OMC or not.
- identify what is causing the peaks if they are originated from the OMC
- correct experimental data for comparison with FEA

Method

- Place a NOLIAC PZT on the object to be excited.
- Look at the actuation signal for the OMC locking to find the excited peaks.

Results

Breadboard

- This configuration excited the modes between 800-1.2kHz most (red curve). As well as the others, the structures above 5kHz are also excited.

- The mode at 1.2kHz was suspected to be the bending mode of the breadboard. To confirm it, metal blocks (QPD housing and a 4" pedestal rod)
  were added on the breadboard to change the load. This actually moved (or damped) the mode (red curve).

- Note that the four corners of the breadboard were held with a PEEK pieces on the transport fixture.
  In addition, the installed OMC has additional counter balance mass on it.
  This means that the actual resonant frequency can be different from the one seen in this experiment. This should be confirmed with an FEA model.
  The breadboard should also exhibit higher Q on the OMCS due to its cleaner boundary condition. 

 

I1OMC_vibration_test_Breadboard.png

DCPD / QPD

- Vibration on the DCPDs and QPDs mainly excited the modes above 3kHz. The resonances between 3 to 5kHz are observed in addition to the ubiquitous peaks above 5kHz.
  So are these coming from the housing? This also can be confirmed with an FEA model.

- Some excitation of the breadboard mode at 1.2kHz is also seen.

 

I1OMC_vibration_test_DCPD.pngI1OMC_vibration_test_QPD.png

CM1/CM2 (PZT mirrors)

- It is very obvious that there is a resonance at 10kHz. This was also seen in the past PZT test. This can be concluded that the serial resonance of the PZT and the curved mirror.
- There is another unknown mode at around 5~6kHz.

- Some excitation of the breadboard mode at 1.2kHz is also seen.

I1OMC_vibration_test_CM.png

FM1/FM2 and Peripheral prism mirrors (BSs and SMs)

- They are all prism mirrors with the same bonding method.

- The excitation is concentrated above 5kHz. Small excitation of the breadboard mode at 1.2kHz is also seen. Some bump ~1.4kHz is also seen in some cases.

I1OMC_vibration_test_FM.png I1OMC_vibration_test_Prism.png

Beam dumps

- The excitation is quite similar to the case of the peripheral mirrors. Some bump at 1.3kHz.

I1OMC_vibration_test_BD.png


Other tapping test of the non-OMC object on the table

- Transport fixture: long side 700Hz, short side 3k. This 3K is often seen in the above PZT excitation

- Fiber coupler: 200Hz and 350Hz.

- The beam splitter for the back scattering test: 900Hz

  209   Tue Jul 15 03:34:16 2014 KojiOpticsCharacterizationOMC backscatter measurement

Backscatter measurement ~ 2nd round


Summary

- The backscatter reflectivity of the 3rd OMC is 0.71 ppm

- From the spacial power distribution, it is likely that this is not the upper limit but the actual specular spot from the OMC,
propagating back through the input path.


Improvement

- The power meter was heavily baffled with anodized Al plates and Al foils. This reduced many spourious contributions from the REFL path and the input beam path.
  Basically, the power meter should not see any high power path.

- The beam dump for the forward going beam, the beamsplitter, and the mirrors on the periscope were cleaned.

- The power meter is now farther back from the BS to reduce the exposed solid angle to the diffused light

- The REFL path was rebuilt so that the solid angle of the PD was reduced.

OMC_backscatter.png


Backscattering measurement

- Pin = 12.3 +/- 0.001 [mW]

- RBS = 0.549 +/- 0.005

- Pback = 4.8 +/- 0.05 [nW] (OMC locked)       ==> ROMC(LOCKED) = 0.71 +/- 0.01 [ppm]

- Pback = 3.9 +/- 0.05 [nW] (OMC unlocked)   ==> ROMC(UNLOCKED) = 0.57 +/- 0.01 [ppm]

Note that the aperture size of Iris(B) was ~5.5mm in diameter. 


V-dump test

- Additional beam dump (CLASS A) was brought from the 40m. This allowed us to use the beam dump before and after the periscope.

- When the beam dump was placed after the periscope: P = 0.9+/-0.05nW

- When the beam dump was placed before the periscope: P=1.0+/-0.1nW

===> This basically suggests that the periscope mirrors have no contribution to the reflected power.

- When the beam dump was placed in the REFL path: P=2.1+/-0.1nW


Trial to find backward circulating beam at the output coupler

The same amount of backreflection beam can be found not only at the input side of the OMC but also transmission side.
However, this beam is expected to be blocked by the beamsplitter. It was tried to insert a sensor card between the output coupler
and the transmission BS, but nothing was found.


In order to see if the detected power is diffused light or not, the dependence of the detected light power on the aperture size was measured.
Note that the dark offset was nulled during the measurement.

IRIS B
aperture   detected
diameter   power

[mm]       [nW]
 1.0        1.1

 2.5        2.6
 4.25       4.0
 5.5        4.6
 8.0        5.3
 9.0        6.1
11.0        6.3
15.0        7.0

We can convert these numbers to calculate the power density in the each ring. 
(Differentiate the detected power and aperture area. Calculate the power density in each ring section, and plot them as a function of the aperture radius)


This means that the detected power is concentrated at the central area of the aperture.
(Note that the vertical axis is logarithmic)

If the detected power is coming from a diffused beam, the power density should be uniform.
Therefore this result strongly suggests that the detected power is not a diffused beam but
a reflected beam from the OMC.

According to this result, the aperture size of 2.6mm in raduis (5.5mm in diameter) was determined for the final reflected power measurement.

Attachment 1: OMC_backscatter.pdf
OMC_backscatter.pdf
  208   Tue Jul 15 03:00:42 2014 KojiOpticsCharacterizationOMC backscatter measurement

Presence of the misaligned SRM (T=20%) was forgotten in the previous entry.
This effectively reduces the OMC reflectivity by factor of 25.

This is now reflected in the original entry. Also the argument about the power spectram density was modified.

Quote:

First, I'm looking at the alog by Zach: https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=8674

I'm not sure how this measurement can be converted into RIN. Well, let's try. Assuming his measurement is done with the single bounce beam from an ITM,
and assuming this plot is already normalized for RIN, we may need to multiply the number on the plot by factor of two or so. Then it's about factor of 5 lower RIN
than the expected RIN. And in terms of R, it is 25 times lower.

 

  207   Sun Jul 13 17:46:28 2014 KojiOpticsCharacterizationOMC backscatter measurement

Backscattering reflectivity of the 3rdOMC was measured.


Attached: Measurement setup

1) A CVI 45P 50:50 BS was inserted in the input beam path. This BS was tilted from the nominal 45 deg so that the reflection of the input beam is properly dumped.
This yielded the reflectivity of the BS deviated from 45deg. The measured BS reflectivity is 55%+/-1%.

2) The backward propagating beam was reflected by this BS. The reflected beam power was measured with a powermeter.

3) The powermeter was aligned with the beam retroreflected from the REFL PDH and the iris in the input path. The iris was removed during the measurement
as it causes a significant scatter during the measurement.

4) While the cavity was either locked or unlocked, no visible spot was found at the powermeter side.


The input power to the OMC was 14.6mW. The detected power on the powermeter was 66.0+/-0.2nW and 73.4+/-0.3nW with the cavity locked and unlocked, respectively.
This number is obtained after subtraction of the dark offset of 5.4nW.

Considering the reflectivity of the BS (55+/-1%) , the upper limit of the OMC reflectivity (in power) is 8.18+/-0.08ppm and 9.09+/-0.09ppm for the OMC locked and unlocked respectively. Note that this suggests that the REFL path has worse scattering than the OMC cavity but it is not a enough information to separate each contribution to the total amount.


Impact on the OMC transmission RIN in aLIGO:

- The obtained reflectivity (in power) was 8ppm.
- For now, let's suppose all of this detected beam power has the correct mode for the IFO.
- If the isolation of the output faraday as 30dB is considered, R=8e-9 in power reaches the IFO.
- The IFO is rather low loss when it is seen as a high reflector from the AS port.
- Thus this is the amount of the light power which couples to the main carrier beam.

When the phase of the backscattered electric field varies, PM and AM are produced. Here the AM cause
the noise in DC readout. Particularly, this recombination phase is changing more than 2 pi, the fringing
between the main carrier and the backscattered field causes the AM with RIN of 2 Sqrt(R).

Therefore, RIN ~ 2e-4 is expected from the above of backscattering.


Now I'm looking for some measurement to be compared to with this number.

First, I'm looking at the alog by Zach: https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=8674

I'm not sure how this measurement can be converted into RIN. Well, let's try. Zach told me that the measured value is already normalized to RIN.
He told me that the modulation was applied at around 0.1Hz. The maximum fringe velocity was 150Hz from the plot.
At 100Hz, let's say, the RIN is 2e-6 /rtHz. The fringe speed at 100Hz is ~70Hz/sec. Therefore the measurement stays in the 100Hz freq bin
only for delta_f/70 = 0.375/70 = 5.3e-3 second. This reduces the power in the bin by sqrt(5.3e-3) = 0.073.

2e-6 = 2 sqrt(R) *0.73 ==> R = 2e-10

This number is for the combined reflectivity of the OMC and the OMC path. Assuming 30dB isolation of the output Faraday
and 20% transmission of SRM, the OMC reflectivity was 5e-6. This is in fact similar number to the measured value.

If I look at the OMC design document (T1000276, P.4), it mentions the calculated OMC reflection by Peter and the eLIGO measurement by Valera.
They suggests the power reflectivity of the order of 1e-8 or 1e-7 in the worst case. This should be compared to 8ppm.
So it seems that my measurement is way too high to say anything useful. Or in the worst case it creates a disastrous backscattering noise.


So, how can I make the measurement improved by factor of 100 (in power)

- Confirm if the scattering is coming from the OMC or something else. Place a good beam dump right before the OMC?

- Should I put an aperture right before the power meter to lmit the diffused (ambient) scatter coming into the detector?
  For the same purpose, should I cover the input optics with an Al foil?

- Is the powermeter not suitable for this purpose? Should I use a PD and a chopper in front of the OMC?
  It is quite tight in terms of the space though.

- Any other possibility?

Attachment 1: OMC_backscatter.pdf
OMC_backscatter.pdf
  206   Fri Jul 11 00:06:33 2014 KojiOpticsCharacterizationI1OMC PD

DCPD#             DCPD1      DCPD2
Housing#          #009       #010
Diode#            #07        #10
Shim              1.00mm 01  1.00mm 02   (1.00mm = D1201467-09)

-------------------------------------
Power Incident     11.1 mW   10.6 mW
Vout                7.65 V    7.33 V

Responsivity[A/W]   0.69      0.69
Q.E.                0.80      0.81
-------------------------------------
photo              2nd        1st

 

PD alignment confirmation

  205   Thu Jul 10 23:22:28 2014 KojiOpticsCharacterizationI1OMC QPD

QPD#              QPD1       QPD2
Housing#          #006       #007
Diode#            #50        #51
Shim              1.25mm 03  1.25mm 02   (1.25mm = D1201467-10)

-------------------------------------
Power Incident    123.1-13.0 uW  124.5-8.0 uW
Sum Out            77.0 mV   82.5 mV
Vertical Out      -24.0 mV  - 8.8 mV
Horizontal Out      4.2 mV    9.0 mV
SEG1              -11.6 mV  -16.0 mV
SEG2              -12.6 mV  -18.0 mV
SEG3              -25.2 mV  -24.4 mV
SEG4              -21.4 mV  -21.4 mV
-------------------------------------
Spot position X   -21   um  -19   um  (positive = more power on SEG1 and SEG4)
Spot position Y   +102  um  +47   um  (positive = more power on SEG3 and SEG4)
-------------------------------------

Responsivity[A/W] 0.70      0.71
Q.E.              0.82      0.83
-------------------------------------

Arrangement of the segments
View from the beam
/ 2 | 1 X
|---+---|
\ 3 | 4 /

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

I(w,x,y) = Exp[-2 (x^2 + y^2)/w^2]/(Pi w^2/2)

(SEG_A+SEG_B-SEG_C-SEG_D)/(SEG_A+SEG_B+SEG_C+SEG_D) = Erf[sqrt(2) d/w]

d: distance of the spot from the center
w: beam width

  204   Thu Jul 10 08:34:57 2014 KojiGeneralGeneralTo Do

Optical tests

  • Cleaning
  • Power Budget
  • FSR measurement
  • TMS measurement
  • TMS measurement (with DC voltage on PZTs)
  • PZT DC response
  • PZT AC response
  • QPD alignment
  • DCPD alignment

Backscattering test

Cabling / Wiring

  • Attaching cable/mass platforms
  • PZT cabling
  • DCPD cabling (to be done at LHO)
  • QPD cabling (to be done at LHO)

Vibration test

Baking

First Contact

Packing / Shipping

  203   Thu Jul 10 01:39:38 2014 KojiElectronicsGeneralPZT wire

Rich came to the OMC lab. Pins for the mighty mouse connector were crimped on the 4 PZT wires.
We found the male 4pin mighty mouse connector in the C&B area.

The cable inventory was checked with ICS/DCC combo. It turned out that most of the on-board cables
are at LHO. We decided to send the OMC there and then the cables are installed at the site.

Attachment 1: P7096669.JPG
P7096669.JPG
  202   Tue Jul 8 18:54:54 2014 KojiMechanicsCharacterizationPZT characterization

Each PZT was swept with 0-150V 11Hz triangular wave.
Time series data for 0.2sec was recorded for each PZT.

The swept voltage at the resonances were extracted and the fringe number was counted.
Some hysteresis is seen as usual.

The upward/downward slopes are fitted by a linear line.

The average displacement is 11.3nm/V for PZT1 and 12.7nm/V.

The PZT response was measured with a FFT analyzer. The DC calibration was adjusted by the above numbers.

Attachment 1: PZT_Scan.pdf
PZT_Scan.pdf
Attachment 2: I1OMC_PZT_Response.pdf
I1OMC_PZT_Response.pdf
  201   Tue Jul 8 04:08:06 2014 KojiGeneralGeneralExpoxy reapplication for beam dumps

Firstly, the excess epoxy was removed using a cleaned razor balde

Secondly, EP30-2 epoxy was applied at the exterior edges of the beam dump.
Interior of the V were glued at two points. This is to keep the gap away from being trapped

Here is the result of the gluing. Some epoxy was sucked into the gap by capillary action.
I believe, most of the rigidity is proivded by the bonds at the edges.

  200   Mon Jul 7 01:36:03 2014 KojiGeneralGeneralTo Do

Optical tests

  • Cleaning
  • Power Budget
  • FSR measurement
  • TMS measurement
  • TMS measurement (with DC voltage on PZTs)
  • PZT DC response
  • PZT AC response
  • QPD alignment
  • DCPD alignment

Backscattering test

Cabling / Wiring

  • Attaching cable/mass platforms
  • PZT cabling
  • DCPD cabling
  • QPD cabling

Vibration test

Baking

First Contact

Packing / Shipping

  199   Sun Jul 6 08:31:14 2014 KojiOpticsCharacterizationHOM measurement with PZT vol swept

3rd OMC, HOM diagram at PZT1=0V and PZT2=50V.

First coincidence with the carrier is the 32nd-order carrier mode. Very good.

Attachment 1: HOM_plot.pdf
HOM_plot.pdf
  198   Sun Jul 6 03:56:40 2014 KojiOpticsCharacterizationHOM measurement with PZT vol swept

Cavity FSR/TMS measurement (2014/7/5) with PZT voltages swept from 0V to 200V (50V step)

Attachment 1: Cav_scan_response_PZT1.pdf
Cav_scan_response_PZT1.pdf Cav_scan_response_PZT1.pdf Cav_scan_response_PZT1.pdf Cav_scan_response_PZT1.pdf Cav_scan_response_PZT1.pdf Cav_scan_response_PZT1.pdf Cav_scan_response_PZT1.pdf Cav_scan_response_PZT1.pdf
Attachment 2: Cav_scan_response_PZT2.pdf
Cav_scan_response_PZT2.pdf Cav_scan_response_PZT2.pdf Cav_scan_response_PZT2.pdf Cav_scan_response_PZT2.pdf Cav_scan_response_PZT2.pdf Cav_scan_response_PZT2.pdf Cav_scan_response_PZT2.pdf Cav_scan_response_PZT2.pdf
Attachment 3: OMC_HOM_140705.pdf
OMC_HOM_140705.pdf
  197   Sun Jul 6 02:46:20 2014 KojiOpticsCharacterizationOMC power budget

3rd OMC power budget (2014/7/2)

Input power: 34.8mW

REFLPD dark offset:  -7.57mV
REFLPD unlocked: 6.22 V
REFLPD locked: 110mV

Transmitted Power: 16.8mW (T) and 15.9mW (R)
CM1 transmission: 0.176mW
CM2 transmission: 0.181mW

Cavity Finesse: 399.73


Junk light: 0.64mW (out of 34.8mW)
Coupled beam: 34.16 mW (out of 34.8mW)
Mode Matching: 0.982
Cavity reflectivity: 467ppm
Loss per mirror in ppm: 63.8ppm
Cavity transmission (for TEM00 carrier): 0.957

FM1: R = 0.992277, T = 7659.46
FM2: R = 0.992277, T = 7659.46
CM1: R = 0.999895, T = 41.5461
CM2: R = 0.999893, T = 42.7309


Compare the above number with the best result obtained during the alignment trials

Input power: 34.4mW

REFLPD dark offset:  -7.5mV
REFLPD unlocked: 5.99 V
REFLPD locked: 104mV

Transmitted Power: Total 32.7mW (T+R)
CM1 transmission: 0.194mW
CM2 transmission: 0.194mW

Cavity Finesse: 400


Junk light: 0.631mW (out of 34.4mW)
Coupled beam: 33.77 mW (out of 34.4mW)
Mode Matching: 0.982
Cavity reflectivity: 255ppm
Loss per mirror in ppm: 39.7ppm
Cavity transmission (for TEM00 carrier): 0.968


  196   Sun Jul 6 02:45:56 2014 KojiOpticsGeneralFSR Measurement

3rd OMC FSR / Finesse measurement

RF AM was injected by detuning a HWP.

Attachment 1: finesse_measurements_log.pdf
finesse_measurements_log.pdf
  195   Thu Jul 3 17:45:18 2014 KojiGeneralGeneralBeam dump delamination

Here is the resolution.

I'll apply fillets of EP30-2 along the edges of the black glass (See figure).
In order to allow the air escape from the gap, the inside of the V will not be painted.
In any case, I don't have a good access to the interior of the V.

Dennis assured that the outgassing level will be ok even if the EP30-2 is cured at the room temp if the mixture is good.
But just in case, we should run an RGA scan (after 50degC for 24hour vac bake).
I prefer to do this RGA scan right after all of the test and cabling and right before the shipment.
Dennis is checking if we can even waive the RGA scan owing to the small volume of the glue.

beamdump_delamination_solution.png

  194   Wed Jul 2 18:58:42 2014 KojiGeneralGeneralBeam dump delamination

While the OMC breadboard was being inspected, it was found that two out of five black-glass beam dumps showed sign of delamination.
(attached photos).

The base of the each beam dump is a fused silica disk (25mm dia.). The black glass pieces are bonded to the disk. The bond is EP30-2
epoxy without glass beads for bond lining. The disk is bonded on the fused silica bread board with Optocast UV low-viscous epoxy.
The delamination is about 70% of the bonded area. They don't seem to fall off immediately. But the glass pieces are not completely secure.
(i.e. finger touch can change the newton ring fringes) So there might be some risk of falling off during transportation.

The engineering team and I are exploring the way to secure them in-situ, including the method to apply UV epoxy with capillary action.

Attachment 1: beamdump_delamination.png
beamdump_delamination.png
  193   Wed Jul 2 16:41:43 2014 KojiGeneralGeneralOMC baking

OMC is back from the oven today.

To Do:

Optical tests

  • Cleaning
  • Power Budget
  • FSR measurement
  • TMS measurement
  • TMS measurement (with DC voltage on PZTs)
  • PZT DC response
  • PZT AC response
  • QPD alignment
  • DCPD alignment
  • First Contact

Backscattering test

Cabling / Wiring

  • Attaching cable/mass platforms
  • PZT cabling
  • DCPD cabling
  • QPD cabling

Vibration test

Packing / Shipping

  192   Fri Jun 27 18:51:33 2014 KojiGeneralGeneralSupply

PTOUCH TAPE (12mm white) x 2

9V batteries

  191   Fri Jun 27 12:29:50 2014 KojiGeneralGeneralOMC baking

The OMC went into the oven at around 2PM on Thursday. It will be baked at 80degC for 48 hours.
The RGA result will be obtained on Monday.

Link to the ICS entry

P6266536.jpg

  190   Tue Jun 24 18:43:15 2014 KojiGeneralGeneralICS entries for the OMC baking/assembly

For baking:

  • Assembly Name aLIGO Output Mode Cleaner
    Assembly Number D1201439
     
  • Part Name: Breadboard transport fixture
    Part # / Drawing #: D1201515
     

TO BE ADDED TO THE ASSEMBLY after the bake: [DONE]
803-003-07M6-4PN-598A-0-Bulk-H42Q001
D1201274-V1-00-S009: OMC DCPD Housing        (remove part)
D1201274-V1-00-S010: OMC DCPD Housing        (remove part)
D1201275-V1-00-0006: OMC DCPD FACE PLATE        (remove part)
D1201275-V1-00-0007: OMC DCPD FACE PLATE        (remove part)
D1201280-V1-00-0006: OMC QPD HOUSING        (remove part)
D1201280-V1-00-0007: OMC QPD HOUSING        (remove part)
D1201281-V1-00-0006: OMC QPD FACE PLATE        (remove part)
D1201281-V1-00-0007: OMC QPD FACE PLATE        (remove part)
D1300052-V1-00-0003: aLIGO OMC BRACKET, CABLE CONNECTOR        (remove part)
D1300057-v2-00-0021: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0022: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0023: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0024: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0025: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0026: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0027: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0028: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0029: aLIGO CABLE PEG        (remove part)
D1300057-v2-00-0030: aLIGO CABLE PEG        (remove part)
D1300060-V1-00-0005: aLIGO OMC BRACKET, MASS MOUNTING        (remove part)
D1300060-V1-00-0006: aLIGO OMC BRACKET, MASS MOUNTING        (remove part)


====================================
More entries to be added (Found in the LHO OMC entry) [DONE]
D1300371-V2-00-S1301806: ISC DCPD Cable for OMC-Breadboard Bracket to DCPD #1
D1300372-V2-00-S1301807: ISC DCPD Cable for OMC-Breadboard Bracket to DCPD #2
D1300373-V3-00-S1301810: ISC QPD Cable for OMC-Structure to Breadboard Bracket
D1300374-V2-00-S1301813: ISC QPD Cable for OMC-Breadboard Bracket to QPD #1

  189   Mon Jun 23 21:54:16 2014 KojiOpticsGeneralAll of the gluing completed

The bottom-side templates were removed.

The last beam dump was removed

TODO

ICS entry

Bring the OMC to the bake lab

Vacuum baking

Bring it back to the OMC lab

Cabling / Wiring

VIbratin test

Optical tests

Backscattering test

Packing / Shipping

 

  188   Fri Jun 20 18:59:12 2014 KojiOpticsGeneralAll of the invar blocks have been glued

All of the INVAR blocks have been glued.

I found thinner shims in the stock.

On Monday, the template will be removed.

EP30-2 7g mixed with 0.35g of 75-90um sphere


TODO

EP30-2 gluing of the INVAR blocks for the PDs

PDs/QPDs need to be slightly lower -> order more shims

Remove the templates

Glue the last beam dump

Vibration test?

Bring the OMC to the bake lab

Vacuum baking

Bring it back to the OMC lab

Cabling / Wiring

Optical tests

Backscattering test

Packing / Shipping

  187   Thu Jun 19 23:16:50 2014 KojiOpticsGeneralAll of the prisms have been glued

- All of the PRISM mirrors have been glued

- 4 out of 5 beam dumps have been glued


TODO

EP30-2 gluing of the INVAR blocks for the PDs

PDs/QPDs need to be slightly lower -> order more shims

Remove the templates

Glue the last beam dump

Vibration test?

Bring the OMC to the bake lab

Vacuum baking

Bring it back to the OMC lab

Cabling / Wiring

Optical tests

Backscattering test

Packing / Shipping

P6196525.JPG

  186   Sat May 17 07:40:14 2014 KojiOpticsCharacterizationI1OMC cavity mirrors glued

I1OMC cavity mirrors were glued.

FSR = 264.82MHz => Lcav = 1.132m (nominal 1.132m)

TMS/FSR for Vpzt1=Vpzt2=0: 0.2185 (V) and 0.2196 (H) (nominal 0.219)

 

aLIGO OMC: Power Budget 2014/5/16

<<<Measured Values>>>
Input Power: 35.7 [mW]
Transmitted Power through FM2: 33.5 [mW]
Transmitted Power through CM1: 0.188 [mW]
Transmitted Power through CM2: 0.192 [mW]
Reflection PD DC output (Unlocked): 6.2 [V]
Reflection PD DC output (Locked): 0.096 [V]
Reflection PD DC output (Dark Offset): -0.00745 [V]
Assumed cavity finesse : 400.

<<<Results>>>
Input Power: 35.7 [mW]
Uncoupled light Power (Junk light + sidebands): 0.575698 [mW]
Input TEM00 Carrier Power: 35.1243 [mW]  (Ratio: 0.983874)
Cavity reflectivity (in power): 548.319 ppm
Cavity transmission (in power): 0.953756
Loss per mirror: 70.1183 ppm
FM1 power transmission: 7640.17 ppm
FM2 power transmission: 7640.17 ppm
CM1 power transmission: 43.2093 ppm
CM2 power transmission: 44.1337 ppm

 

Attachment 1: Cav_scan_response_140516_Pitch.pdf
Cav_scan_response_140516_Pitch.pdf
Attachment 2: Cav_scan_response_140516_Yaw.pdf
Cav_scan_response_140516_Yaw.pdf
ELOG V3.1.3-