DGS calibration

The DGS input/input output voltage ranges are:

ADC:  ± 20 V

DAC:  ± 5 V

The volts to counts calibration is  2^15/(Vpk):

ADC: 1 V  =  1638 count

DAC: 1 V  =  6544 count 

Measurement of phase noise of coherent control PLL

I followed the Marco method and measured the phase noise of CC PLL. It shows an RMS phase noise of 149mrad. It is almost 50 times higher than p-pol PLL phase noise level.

p-pol PLL servo correction signal

I measured the p-pol PLL fast and slow loop correction signal. We can see from the attached figure. Although at that time fast loop is not stable, it shows very low-frequency drift. But slow loop reads this signal can try to bring the loop back to the original state. Since I calculated the correlation coefficient of these two signal, the slope of these two signal is the same. So the correlation coefficient is -1.

I think this is better than the coherent control loop. It is measured and shown in the entry here.

Coherent control loop realized by Pierre

Yuhang and Pierre

We tune the servo for locking the coherent control loops.

For green coherent control, we use 20dB attenuator and 50Om for error in. The measured open loop transfer function is attached as figure 1. We have unity gain frequency of 85Hz.

For local oscillator coherent control, we use 30dB attenuator and 50Om for error in. The measured open loop transfer function is attached as figure 2. We have unity gain frequency of 51Hz.

IR injection and reflection telescope update

I did another simulation for injection (-400 mm focal is not a common lens) and for the reflection (avoiding to change the already installed injection telescope into the homodyne).

The robustness for the injection telescope is really good, less than 3% moving the first lens in a range of +/- 5mm and less than 10% for the other one.

The robustness for the reflection telescope is not as good, we reach also 20% mismatch for +/- 5mm movement of one lens.

Squeezing and anti-squeezing spectrum

Modification of the CC-2 Servo-filter (IR Phase Coherent Control)

The following settings and modifications were done for the CC-2 (IR Phase Coherent Control) Servo-filter to the original Servo-filter which electronic schematics and bill of material are saved on the wiki.

0- Current configuration:

Notch filter 1, Notch filter 2 ans LP filter are disable.
The Servo-filter must be set only on 1/f integrator.
An attenuator of 30dB with a 50 Ohm load is set on the ERROR IN input.
The gain is set to minimum (position 0).
The unity gain frequency was measured to 50Hz.


1-Setting of switches on the front panel:

* The differentiator shall be disabled on the front panel in setting the switch on "OFF".

* The switch INV/NON INV on the front panel, shall be set on INV.


2-Setting of the 8 straps on the board:

Notch filter 1, notch filter 2 and Low-pass filter are disabled in setting strap on connectors P7, P8 and P9 between pins 2 and 3.

* The transmission signal is ont used.
The strap on connector P4 (3 pins) is set between pin 2 and 3.

* Strap is set on connector P11 (3 pins), between pins 2 and 3, in order to activate the sample-and-hold on the triangular signal, on the locking.
* Strap is set on connector P3 (2 pins) to connect the triangular signal to the output stage.

* Strap is set on connector P2 (3 pins), between pins 1 and 2, for test purpose.
To check notch 1 and notch 2 filters (in scan mode) between TEST IN and TEST OUT. For this test the differentiator, shall be set on "ON" (not intuitive but important). After this test, the differentiator shall be disabled the front panel in setting the switch on "OFF".

* Strap is set on connector P1 (2 pins), in order to be able to tune the offset.


3-Modification of components:

* Integrator 1/f: corner frequency changed to 22 kHz
Capacitor CMS 1206: C38 = 3.3nF

* Integrator 1/f2: unchanged

* Low-pass filter: unchanged

* Notch filter 1: unchanged

* Notch filter 2: unchanged

* Gain adjustment (G): Gmin = 0.0125 / Gtyp = 5

* Input impedance
Resistor CMS 1206 : R145 and R146 removed

Modification of the CC-1 Servo-filter (Green Phase Coherent Control)

The following settings and modifications were done for the CC-1 (Green Phase Coherent Control) Servo-filter to the original Servo-filter which electronic schematics and bill of material are saved on the wiki.

0- Current configuration:

Notch filter 1, Notch filter 2 ans LP filter are disable.
The Servo-filter must be set only on 1/f integrator.
The gain is set to minimum (position 0).
An attenuator of 20dB with a 50 Ohm load is set on the ERROR IN input.
The unity gain frequency was measured to 85Hz.


1-Setting of switches on the front panel:

* The differentiator shall be disabled on the front panel in setting the switch on "OFF".

* The switch INV/NON INV on the front panel, shall be set on INV.


2-Setting of the 8 straps on the board:

Notch filter 1, notch filter 2 and Low-pass filter are disabled in setting strap on connectors P7, P8 and P9 between pins 2 and 3.

* The transmission signal is ont used.
The strap on connector P4 (3 pins) is set between pin 2 and 3.

* Strap is set on connector P11 (3 pins), between pins 2 and 3, in order to activate the sample-and-hold on the triangular signal, on the locking.
* Strap is set on connector P3 (2 pins) to connect the triangular signal to the output stage.

* Strap is set on connector P2 (3 pins), between pins 1 and 2, for test purpose.
To check notch 1 and notch 2 filters (in scan mode) between TEST IN and TEST OUT. For this test the differentiator, shall be set on "ON" (not intuitive but important). After this test, the differentiator shall be disabled the front panel in setting the switch on "OFF".

* Strap is set on connector P1 (2 pins), in order to be able to tune the offset.


3-Modification of components:

* Integrator 1/f: corner frequency changed to 22 kHz
Capacitor CMS 1206: C38 = 3.3nF

* Integrator 1/f2: corner frequency changed to 22.5 Hz
Capacitor CMS 1206: C26 = C33 = 2200nF
Capacitor CMS 1206: C25 = C32 = 1000nF

* Low-pass filter: unchanged

* Notch filter 1: notch frequency changed to 11.8 kHz / quality factor changed to 0.9 (measured)
[Capacitor CMS 0805 1% : C49 ; C50 ; C51 ; C53 = unchanged (560 pF)]
Resistor CMS 1206 : R65 ; R66 ; R67 ; R68 = 24k
Resistor CMS 1206 : R73 = 13k

* Notch filter 2: notch frequency changed to 14.2 kHz / quality factor changed to 4.85 (measured)
[Capacitor CMS 0805 1% : C60 ; C61 ; C62 ; C63 = unchanged (560 pF)]
Resistor CMS 1206 : R79 ; R80 ; R81 ; R82 = 16k
Resistor CMS 1206: R89 = 1.3k

* Gain adjustment (G): Gmin = 0.4 / Gmax = 16.5 / Gtyp = 6

* Input impedance
Resistor CMS 1206 : R145 and R146 removed

Re-alignment of ML PLL fiber and homodyne

Comment to IR injection and reflection telescopes new scheme (Click here to view original report: 1305)

-200 lens for reflection telescope is on OPO transmission path and it changes mode matching of OPO transmission. So this configuration is not feasible.

IR injection and reflection telescopes new scheme

I found a new solution, better than the previous one, considering a larger database of lenses.

The robustness is good, moving one lens in a range of 1cm, the total mismatch is lower than 20%.

More boards for GALVO control

I have found (between BS adn NM1 chamber) a rack with 5 more boards for the galvo control. See attached picture.

Maybe some of them are the "new version" Yuefan was talking about?

On two of them there is also a label specifing if the QPD has big or small range. 

PR yaw loop closed with new DGS

After solving the DGS issue with the filter loading, I could test the simulink model on the control of YAW of PR.

The mechanical TF and the closed loop TF are shown in pic 1 and 2.  The comparison between the open and closed loop spectrum is shown in pic 3. The control seems to work fine.

UGF is at ~ 6 Hz and phase margin is ~ 50 deg.  A first, rather basic version of medm screen developped for the control is shown in pic 4.

Error and correction signals are currenty in counts and needs to be calibrated.

200Hz noise from our cleaning room fan

Today we used the sound spectrum analyzer characterized the sound environment. We found a clear frequency from our cleanroom fan. It is 200Hz.

Broken connector for Alignment-Mode-Cleaner PZT

Yuhang, Pierre, Aritomi

In the beginning, we tried to check the alignment of homodyne. But we cannot see a meaningful signal from AMC transmission.

We found the PZT of AMC was broken. I guess it is related with the strong force we(mainly it's me) enforced on this connector or its wire. I am sorry that I made very ugly soldering.

Anyway, we repaired it and we heard the sound of PZT by sending a 4kHz signal.

So in the future, let's be kind for our wires!

Robustness of injection telescope and reflection telescope

I report the robustness of the injection and reflection telescopes described in entry #1296.

The two telescopes can be consiedered robust enough (till 20% of mismath) only in a range of +/- 2 mm.

DGS: Filter loading issue fixed going back to old version

[T.Yamamoto, Y.Fujii, Eleonora]

Here the report from Yamamoto-san about today's work:

- Real-time models was not able to read filter files.
Models detected the modification of filter files.
But “COEFF LOAD” button did not work well.

- We unified the RCG version as v3.1.1.
At first master and slave model run as v2.8.8 and v3.1.1, respectively.
But the problem was not solved by unifying the version.

- System clock of STDA on BIOS was fixed.
System clock should be set as UTC. But it was set as JST.
So system time showed 9 hours future and date of file modification was wrong.
We fixed the time-stamp of filter file, but problem was not solved.

- Filter files re-generated after fixing system clock.
We moved filter files and re-generated them by rebuilding models.
But the problem was not solved.

- The version of real-time system returned back form v3.1.1 to v2.8.8.
The problem was solved by using v2.8.8.

#####################

Thanks a lot to Yamanoto-san and Fujii-san for the precious help and for all the time spent!

IR injection e reflection telescope

I made new simulations taking into account also the telescope for the beam reflected from the cavity into the homodyne. 

Injection telescope:

focal lenght 1 = -101.65 mm

focal lenght 2= 204.6 mm

Reflection telescope:

focal lenght 1= 203.3 mm

focal lenght 2 = -101.65 mm

In fig 3 you can find the scheme of the two telescopes on the bench.

Next step:

- Test the two telescopes

Comment to System performances with CC power reduced (Click here to view original report: 1252)

I just measured there are 3uW of p-pol is going also into homodyne.

Modification of the OPO Servo-filter

The following settings and modifications were done for the OPO Servo-filter to the original Servo-filter which electronic schematics and bill of material are saved on the wiki.


1-Setting of switches on the front panel:

* The differentiator shall be disabled on the front panel in setting the switch on "OFF".

* The switch INV/NON INV on the front panel, shall be set on INV.


2-Setting of the 8 straps on the board:

Low-pass filter, Notch filter 1 and notch filter 2 are activated on the board in setting strap on connectors P7, P8 and P9 (3 pins) between pins 1 and 2

* The transmission signal is positive with a peak at 1.26V.
It shall be inverted: the strap on connector P4 (3 pins) is set between pin 2 and 3.
The threshold level must normally be tuned to a negative level of 600mV (THRESHOLD OUT).
We had also to increase the sample-hold capacitor (C89). See below.

* Strap is set on connector P11 (3 pins), between pins 2 and 3, in order to activate the sample-and-hold on the triangular signal, on the locking.
* Strap is set on connector P3 (2 pins) to connect the triangular signal to the output stage.

* Strap is set on connector P2 (3 pins), between pins 1 and 2, for test purpose.
To check low-pass filter, notch 1 and notch 2 filters (in scan mode) between TEST IN and TEST OUT. For this test the differentiator, shall be set on "ON" (not intuitive but important). After this test, the differentiator shall be disabled the front panel in setting the switch on "OFF".

* Strap is set on connector P1 (2 pins), in order to be able to tune the offset.


3-Modification of components:

* Integrator 1/f: corner frequency changed to 3.3 kHz
Capacitor CMS 1206: C38 = 22nF

* Integrator 1/f2: corner frequency changed to 220 Hz
Capacitor CMS 1206: C26 = C33 = 330nF

* Low-pass filter: cut-off frequency changed to 3.3 kHz
Capacitor CMS 0805 : C45 = 2.2nF (0805)
Resistor CMS 1206 : R59 = 22k

* Notch filter 1: notch frequency changed to 10.5 kHz / quality factor changed to 6 (measured)
[Capacitor CMS 0805 1% : C49 ; C50 ; C51 ; C53 = unchanged (560 pF)]
Resistor CMS 1206 : R65 ; R66 ; R67 ; R68 = 27k
Resistor CMS 1206 : R73 = 820

* Notch filter 2: notch frequency changed to 14.2 kHz / quality factor changed to 6 (measured)
[Capacitor CMS 0805 1% : C60 ; C61 ; C62 ; C63 = unchanged (560 pF)]
Resistor CMS 1206 : R79 ; R80 ; R81 ; R82 = 20k
Resistor CMS 1206: R89 = 820

* Gain adjustment (G): Gmin = 0.125 / Gmax = 05 / Gtyp = 1
No modification.

* Modification of he sample-hold capacitance on the triangular signal:
Capacitor 1206 of 4.7microFarad added on the 1microFarad capacitor (C89).