ELOG 40m

Arm absl length data taken

[Katrin, Jenne]

We took the data for the new absolute length measurement of both arms, after the latest vent and move. We will analyze soonly. We had done a round of analysis, but then Koji pointed out that our data wasn't so clean because the whitening filters were on (and saturated the ADC). We now have the data (but not the analysis) for the better data with the WF off.

So our dirty-data preliminary number for the X arm is 37.73meters, which is 14cm different from our old length. We were supposed to move by ~20cm, so....either this measurement is bad because the data sucked (which it did), or we are 6cm off. Or both.

I'll do another analysis with the clean data for both arms later today/tomorrow.

5627

Fri Oct 7 04:42:24 2011

DRMI locked and some plans

DRMI has been locked using the same RFPD selection as the old days (i.e. AS55_I, AS55_Q and REFL_I).(#4760)

But remember : this is just a beginning of several measurements and tests to characterize the central part.

Here is a list of the measurements and actions :

- 3f locking related

+ Listing up the necessary RFPDs and their installations.

+ Calibration of the SRM actuator => this is necessary to convert the sensing matrix into unit of [counts/m] or [W/m].

+ Measurement of the sensing matrix => check the performance of 3f signals. Also diagonalization of the LSC sensing matrix

+ Diagonalization of the output matrix.

+ Noise characterization of 3f PDs => confirm the noise are low enough to keep the lock of the central part

- Power-recycling gain issue related (#5541)

+ Estimation of the mode matching efficiency => maybe we can use power-recycled ITMs to estimate it (?)

+ Implementation of auto alignment servos and scripts for MICH, PRCL and SRCL. => integrate it to the existing ASS model

+ Search for a possible loss factor

5628

Fri Oct 7 11:45:24 2011

POY11 installed, 55MHz PD at POY removed

POY11 PD was installed last night. The lock of the Y arm was confirmed with the POY11I signal.

- The DC transimpedance was modified to be 1010V/A as the incident power is tiny.

- The demodulation phase of the roughly adjusted (148deg) to have PDH signal at the I-phase. 
The comparison with AS55I signal exhibits that POY11I have ~150 times weaker signal with 45dB whitening. 
(In total 25000 times weaker.)

On the way to make POY11 functioning, there were many fixes at the LSC rack...

Details:

- The PD interface cards (power supply for the RFPDs) were checked:
So far the two card at the right hand side were checked.  
Desipite the previous entry reported the issues on those boards, they did not show any problem yesterday. 
One hypothetical possibility is the enabling switches that is controlled from the old slow epics targets.

- POY55 was removed 
This 55MHz PD is supposed to be installed at POP.
The PD, an RF cable, an RF amp, the power supply of the RF amp were removed.

- POY11 was installed 
The PD was placed where the 55MHz was placed. 
The beam was aligned on the diode using the IR viewer and the digital multimeter. 
The power supply cable and the RF cable for POY on the ITMY table were used. 
There were an ND filter on the POY beam path. It was removed. 

- On the LSC rack
The PD RF was connected to the patch panel at the top of the rack. 
There were loose connectors on the patch panel. Some connectors were tightened on the panel.

I found that POY11 and POX11 had I&Q signal reversely connected to the whitening board.
==> These were fixed but require the orthogonality test again for those channels.

  The I phase output of the AS11 demod board had a broken connector.  
The onboard SMA has got disintegrated because of too much twist on the connector.
The board was once removed from the rack and the connector was fixed using a heat gun and soldering.

The DC signals were checked. POYDC was not correctly connected. POYDC were correctly connected to the POYDC channel.

- CDS
c1lsc was found with the RFM frozen.
The c1lsc machine was soft-rebooted after stopping all of the RT processes. 
Once the RT processes came back, they were all burtrestored.

- PDH locking
Restored Y-arm. Locked it with AS55Q.
Ran ASS alignment for Y-arm. 100cnt 150Hz sinusoidal signal is applied to ETMY 
Measured the PSD of AS55Q, POY11I, and POY11Q.
Adjusted the demod phase so that the excitation could be minimized in POY11Q. 

5629

Fri Oct 7 11:53:47 2011

DRMI locked and some plans

- REFL165 PD to be fixed (shows constant high voltage at the DC out)

- Make POP22/110 PD

- Install AS11? or use it as POX11?

- Install POP55

5637

Sat Oct 8 00:44:42 2011

calibration of SRM actuator

The AC response of the SRM actuator has been calibrated.

(Summary of the calibration results)

BS = 2.190e-08 / f² [m/counts]
ITMX = 4.913e-09 / f²[m/counts]

ITMY = 4.832e-09 / f² [m/counts]
PRM = 2.022e-08 / f² [m/counts]

SRM = 2.477e-08 / f² [m/counts] ( NEW ! )

(Measurement)

The same technique as I reported some times ago (#4721) were used.

The Signal-Recycled ITMY was locked for measuring the actuator response.

Since the ITMY actuator had been already calibrated, first the sensor was calibrated into [counts/m] by exciting the ITMY actuator and then calibrated the SRM actuator with swept sine measurement.

- - notes to myself

SRCL GAIN = 2.2

Sensor = REFL11_I

Demod. phase = 40 deg

Resonant condition = Carrier resonant

Gain in WF = 0 dB

Quote from #5583

The AC responses of the BS, ITMs and PRM actuators have been calibrated.

5638

Sat Oct 8 04:41:07 2011

length fluctuations in SRCL

For a comparison, the length fluctuation of Signal-Recycled ITMX (SRX) and ITMY (SRY) have been measured.

Roughly speaking the length motion of SRX and SRY are as loud as that of PRCL.

Some details about the measurement and data analysis can be found in the past elog entry (#5582).

In the process of converting the raw spectra to the calibrated displacements the SRM actuator was assumed to have a resonance at 1Hz with Q = 5.

(Notes on SRX/Y locking)

Sensor = REFL11_I

Actuator = SRM

Demod. phase = 40 deg

SRCL_GAIN = 20

UGF = 100 - 200 Hz

Resonant condition = Carrier resonance

Whitening gain = 0 dB

ASDC = 360 counts

Quote from #5582

The MICH and PRCL motions have been measured in some different configurations.

+ PRCL is always noisier than MICH.

5639

Sun Oct 9 17:13:46 2011

First attempt to estimate mode matching efficiency using interferometer

The efficiency of the mode matching (MM) to PRC (Power-Recycling Cavity) has been estimated by using the interferometer.

The estimated MM efficiency is about 74 % when losses in the cavity are assumed to be zero.

(Motivation)

There had been an issue that the recycling gain didn't go to the designed high value of about 42 (#5541).

One of the possibilities is a low efficiency in the MM to PRC (also see #5541).

Although the MM efficiency had been measured using a beam scan ( see a summary on the wiki) a long time ago, it haven't been verified.

Therefore the MM has to be reviewed by using the real interferometer.

(Measurement)

The concept of this measurement is observe the amount of the reflected light from a power-recycled cavity and estimate the MM efficiency based on the measured reflectivities.

Since using the real PRC (consisting of BS, ITMs and PRM) could be a too complicated system for this measurement,

simpler cavities, namely Power-Recycled ITMX and ITMY (PRX and PRY), were used to examine the MM efficiency.

The measurement goes in the following order :

(1) Measurement of the amount of the single-bounce reflection from PRM with BS and ITMs misaligned.

(2) Lock PRX or PRY to carrier resonance.

(3) Alignment of PRX/Y to maximize the intracavity power. This time ASDC was used as a monitor of the intracavity power.

(4) Measurement of the amount of the reflected light when the cavity is in resonance. The value in REFLDC was averaged in 100 sec.

=> done by tdsavg 100 C1:LSC-REFLDC_OUT

The same measurement was performed for both PRX and PRY.

- locking parameters -

Sensor = REFL11_I

Whitening gain = 10 (30 dB)

PRCL_GAIN = 2

UGF ~ 200 Hz

(Analysis)

In order to estimate the relation between the MM efficiency vs. the reflected light, two models are considered:

(1) simple model => no loss and no sidebands

(2) sideband-included model => no loss but sidebands are taken into the account of the reflection.

(1) In the simple model the reflectivity P_refl/ P_in is expressed by

[Reflectivity] = P_refl / P_in = Z * R_cav + (1- Z) * R_prm

where Z is MM efficiency and R_prm is the reflectivity of PRM

and R_cav is the reflectivity of PRX/Y when it's resonance and it is defined by

R_cav = | r_prm - r_itm t²_BS|² / |1 -r_prm r_itm t²_BS |²

T_prm = 5.75% and T_itm = 1.4 % are assumed in all the calculations.

In the first equation the first term represents the mode matched light and hence it couples with the cavity through R_cav.

The second term is the non-mode-matched light and because they are not interacting with the cavity they will be simply reflected by PRM through R_prm.

(2) In reality two phase-modulated light (11 MHz and 55 MHz) will behave differently from the carrier.

For example when the carrier is in resonance the sidebands will be anti-resonance against the cavity.

So that the amount of REFLDC will be slightly bigger because of the reflection of the sidebands.

P_refl = Z * R_cav* P_c + Z * R_anti * P_s + (1- Z) * R_prm * (P_c + P_s)

where P_c and P_s are the power in the carrier light and the sidebands respectively.

And R_anti is the reflectivity of the anti-resonance PRX/Y, which can be obtained by replacing the minus sign by the plus sign in the equation of Rcav shown above.

It is assumed that the sum of the carrier power and sidebands power is the incident power P_in = P_c + P_s.

The power in the carrier and the sidebands were estimated based on the OSA measurement (#5519), so that

P_c / P_in = |J₀(0.14)|² * |J₀(0.17)|² = 0.976

P_s / P_in = 2 * |J₁(0.14)|² + 2 * |J₁(0.17)|² = 0.024

(Results)

Here are the measured values in REFLDC

-- Measurement 1 : PRX

Single bounce from PRM = 4802.27 counts

==> the incident power = 5095.25 counts

Reflected light from PRX = 4433.88 counts

==> Reflectivity = 0.8702

-- Measurement 2 : PRY

Single bounce from PRM = 4833.05 counts

==> the incident power = 5127.05 counts

Reflected light from PRX = 4444.48 counts

==> Reflectivity = 0.86672

On average the reflectivity of power-recycled ITM cavity was 0.868 with a standard deviation of 0.001744.

Actually the standard deviation estimated here is not fair because the measurement was done by only twice,

but my intention was that I wanted to see how the error can affect the estimation of the MM efficiency.

Here is a plot comparing the model curves and the measured values with 5 sigma error box (5 times of measured standard deviation).

It is shown that the mode matching efficiency is 73.7 % when the sideband-included model is considered.

With the 5 sigma deviation it can go from 65% to 82% but it is still low and lower than the beam scan measurement ( see a summary on the wiki).

Anyways the estimated MM efficiency with the sidebands effect included and without loss effect is

MM efficiency = 73.7 +/- 1.7 % (1 sigma error) or +/- 8.7 % (5 sigma error)

5640

Mon Oct 10 00:01:26 2011

First attempt to estimate mode matching efficiency using interferometer

"^2"s are missing in the second equation, but the calculation results seem correct.

PRX and PRY have different mode matching because of the Michelson asymmetry.
Are individually estimated mode matching indicates any sign of reasonable mode mismatch?
(The difference can be very small because the asymmetry is not so big.)

5641

Mon Oct 10 10:14:43 2011

rana

length fluctuations in SRCL

How does it make sense that the motion at 0.1 Hz of PRC is 10x larger than MICH?

EDIT by KI:

That's actually the point which I was wondering at. One possible reason is that my actuator responses are not so accurate below 1Hz.

I will measure the DC response of all the actuators and it will completely determine the shapes of the actuator responses except for the region around the resonance.

In the process of producing the plot I was assuming that all the actuator response have a 1 Hz resonance with Q of 5.

However in reality this assumption is not true because the resonant frequency is different in each actuator.

5643

Mon Oct 10 13:52:04 2011

RE: First attempt to estimate mode matching efficiency using interferometer

Quote from #5640

"^2"s are missing in the second equation, but the calculation results seem correct.

- Thank you for the correction. The missing square operation has been added correctly on the last entry (#5639).

- As for the individual MM efficiency,

I was assuming that the MM solutions are the same for PRX, PRY and the real PRC, so I haven't carefully checked differences between those cavities.

However as you mentioned the difference in those cavities can be tiny due to the small 3 cm Schnupp asymmetry.

Anyway I will briefly check it to make me sure.

5648

Tue Oct 11 03:35:16 2011

BS actuator reponse at low frequency : measured

The response of the BS actuator in a low frequency regime has been measured.

After the measurement I did a coarse fit to see if the low frequency data agree with the high frequency response which I have measured two weeks ago (#5583)

So far it shows a good agreement with the high frequency data (see the plot below). Tomorrow I will do a serious fitting.

Once the calibration of BS is done, the low frequency responses of ITMs, PRM and SRM will be done by simply exciting BS and comparing them (maybe at a couple of frequency points around 0.1Hz).

(Measurement)

+ With free swinging MICH, the sensor (AS55_Q) was calibrated into counts/m.

=> The peak-peak counts was about 110 counts. So the sensor response is about 6.5x10⁸ counts/m

+ Locked Michelson with AS55_Q and the signal was fedback to BS.

+ Set the UGF high enough so that the open loop gain below 10 Hz is greater than 1.

+ With DDT's swept sine measurement, C1:LSC-MICH_EXC was excited with a big amplitude of 40 counts.

+ Took a transfer function from C1:LSC-MICH_OUT to C1:LSC-MICH_EXC.

+ Calibrated the transfer function into m/counts by dividing it with the sensor response.

Quote from #5641

One possible reason is that my actuator responses are not so accurate below 1Hz.

I will measure the DC response of all the actuators and it will completely determine the shapes of the actuator responses except for the region around the resonance.

5649

Tue Oct 11 15:14:50 2011

rana

BS actuator reponse at low frequency : measured

Quote:

The response of the BS actuator in a low frequency regime has been measured.

This seems like an error prone method for DC responses due to the loop gain uncertainty. Better may be to use the fringe hopping method (c.f. Luca Matone) or the fringe counting method

5652

Tue Oct 11 19:11:25 2011

Re: BS actuator reponse at low frequency : measured

I think the precision due to the loop gain uncertainty is something like 0.1% at 0.1 Hz. It's not the issue.

The real issue was the loud motion of MICH, which degrades the coherence of the measurement.

Also last night I tried the fringe hopping technique and gave it up for several reasons.

(uncertainty due to the loop gain)

When MICH is locked, the signal at C1:LSC-MICH_OUT can be expressed in frequency domain by

MICH_OUT = G / (1+G) * (1 / A) * X + G / (1+G) * (1 / H) * (1 / A) * S, [1]

where G is the open loop gain, A is the actuator response, H is the sensor transfer function (constant factor),

X is the natural (unsuppressed) motion of MICH and S is an excitation injected at C1:LSC-MICH_EXC.

When the natural motion of MICH X is smaller than the excited displacement S/H, dividing MICH_OUT by S gives

[Transfer function] = S / MICH_OUT

= (1+G) /G * H * A

At low frequency the open loop gain is always big, so that the transfer function can be approximated to

[Transfer function] ~ H *A

This approximation is valid with a precision of 1/G.

In my case yesterday, the open loop gain at 0.1Hz was about 10³ or more than that, so the uncertainty due to the loop gain was 0.1% or even less.

(Effect from the MICH motion)

In the equation [1], it is shown that the MICH motion X shows up together with the excitation signal.

Actually this MICH motion term was not completely negligible and eventually this term disturbs the measurement resulting in a low coherence.

In order to get a high coherence in the measurement, X should be smaller than the excited displacement S/H,

X << S / H

This the reason why I had to inject a big excitation signal. Although the coherence around 1Hz turned out to be still low due to the loud natural motion in MICH.

The excitation was already close to 0.1 um level in terms of peak-to-peak displacement, and I wasn't able to increase it any more because the MICH signal would run into a nonlinear regime.

In the worst case I lost the lock due to a too much excitation.

(Fringe hopping technique)

Actually I tried and gave up this technique. That's why I did the in-loop measurement.

My feeling is that this technique is not suitable for the 40m.

What I tried was to flip the sign of the MICH control such that the fringe hops from the dark fringe to the neighbor bright fringe or vice versa.

Difference in the control signal (C1:LSC-MICH_OUT) was supposed to give us the amount of signal which drives the actuator by exactly quarter of the laser wave length.

However this technique turned out to be not good because

(1) BS actuator is too strong

=> expected difference in the control signal is quite small.

=> \lambda / 4 / A ~ 12 counts, where A is the actuator DC response of about 2.2e-8 [m/counts].

(2) MICH motion was too loud

=> I saw such a tiny 12 counts difference in the control signal, but once the hopping is done the control signal immediately fluctuated and it was really hard to precisely measure it.

=> It's simply because MICH was loud, and the actuator tried to suppress the motion and it resulted such an immediate signal fluctuation in the control signal

Quote from #5649

This seems like an error prone method for DC responses due to the loop gain uncertainty. Better may be to use the fringe hopping method (c.f. Luca Matone) or the fringe counting method

5653

Tue Oct 11 21:23:51 2011

Quote:

[Katrin, Jenne]

I'll do another analysis with the clean data for both arms later today/tomorrow.

After analyzing the cleaner data, I get the following:

Y_Length_long = 37.757 meters

X_Length_long = 37.772 meters

As stated in the wiki, the goal arm length was L = 37.7974 m for each arm.

So we're within 2cm for X, and within 4cm for Y.

According to Kiwamu's awesome tolerance calculation, we need to be within 2cm for each arm. Given that we started out 20cm wrong for X and 25cm wrong for Y, we're a lot closer now, even though we aren't meeting our Yarm requirement yet.

Probably some Optickle action is in order, to see what these new lengths give us in terms of sideband phase and other stuff.

If you want more digits on my calculated numbers (which are probably meaningless, but I haven't done a careful error analysis), in my directory ...../users/jenne/Xarm and ..../users/jenne/Yarm run Xarm_find_peaks_and_length.m and Yarm_find_peaks_and_length.m respectively. These will output the lengths.

5654

Wed Oct 12 00:35:42 2011

The TRY (TRansmitted light from Y arm ) path was a bit realigned because there had been a small clipping.

This clipping was introducing offsets on the error signals of the C1ASS servo.

(Story)

During I was running the C1ASS servo on the Y arm I found every time after the auto-alignment is done there still remained a slight offset in the beam pointing,

I looked at the CCD camera which looks at the transmitted light and then introduced an intentional misalignment in ETMY in order to find an obvious clipping.

Indeed there was a clipping in horizontal direction. I checked through the optics on the Y end optical bench.

On the second mirror (beam splitter) the beam was on a very edge. So I steered the first steering mirror to fix it,

In addition to that an iris which is placed between the first and second mirror was also clipping the beam,

So I fully opened the aperture of the iris.

5656

Wed Oct 12 17:53:01 2011

BS actuator response : fitting done and histroy of delays

An update on calibration of the BS actuator : A fitting has been done.

(Fitting)

I used LISO for fitting the complex transfer function.

Because the data points around 1 Hz didn't have big coherence a few data points, which had coherence of less than 0.9, were excluded.

Also the fitting of the Q-factor wasn't successful due to the lack of good data points around the resonance.So I left Q fixed to be 5 in the fitting.

(Fitting result)

G = 2.18060874008e-8 +/- 6.425e-10 (2.95%)
f0 = 1.0100491195 +/- 1.51e-2 (1.49%) [Hz]

Q = 5 (fixed)

delay = 423.2753462089e-6 +/- 4.989e-6 (1.18%) [sec]

(History of delay)

Because we have been observing several different amount of delays in different configurations, perhaps it is worth to summarize those numbers.


description	delay [usec]	elog entry
MICH lock (BS actuation)	423	this entry
LSC feed forward path	127	#5218
MICH lock (BS actuation)	600	#4638
ALS on X arm (ETMX actuation)	330	#4196
RFM (from c1lsc to c1sus)	125	#4153
from ADC to DAC (all the front end machine)	38-110	#3961
from ADC to DAC (c1sus)	124	#3838
RFM (c1ioo and c1sus)	8-62	#3855

Quote from #5648

Tomorrow I will do a serious fitting.

5659

Thu Oct 13 03:22:53 2011

measurement of sensing matrix : just began

- status update on LSC activity :

The measurement of the LSC sensing matrix has begun. But no useful results yet.

The measurement script (#4850) ran pretty well after I did some modifications to adopt the script to the latest LSC model.

However the SNR weren't so great particularly in REFL33 in the PRMI configuration.

So I will tune the amplitude of excitations and integration times tomorrow.

Currently the excitation is at 238.1 Hz, where no disturbing structures are found in the spectra.

5664

Thu Oct 13 23:58:38 2011

I already have reported in this entry that REFL165 shows too high DC output which does not depend on the light level on the diode.
Today I removed REFL165 from the table and inspected it.

The diode has been burnt as shown in the first picture (left).
The window is smoked, and the photo sensitive surface has been removed from its base. It moves in the can.

The burnt diode was replaced to the new one.
The new one shows ~30% better capacitance of ~50pF and I had to increase the inductance from 14nH (i.e. 15nH//220nH) to 18nH.
After some struggles to increase/decrease the stray inductance by moving the SMD capacitors a little, the resonance is reasonably tuned to 166MHz.

The comprehensive test will be performed shortly.

Attachment 1: PA131612.jpg

Attachment 2: PA131618.jpg

5665

Fri Oct 14 04:35:45 2011

The lock of DRMI wasn't stable enough to measure the sensing matrix. Failed.

PRMI and SRMI were okay and in fact they could stay locked robustly for a long time.

I added a new option in the C1IFO_CONFIGURE screen so that one can choose Signal-Recycled Michelson in carrier resonant condition.

Additionally the orthogonalization of the I-Q signals on REFL55 should be done because it hasn't been done.

5671

Sat Oct 15 16:42:08 2011

Test results of new REFL165 (the first attachment)

- The resonant freq 166.2MHz, Q=57 (previous Q was ~7)

- If we believe the TF measurement, the transimpedance at the resonance is 7.8k [V/A] and the shotnoise intercept current of ~1mA.
The linearity of the peak was confirmed by changing the modulation level of the beam.

- There is a riddle: the white light test indicates 4.5k [V/A] and 2.8mA for those numbers.
There are big descrepancies from those by the TF measurements.

Further analysis of the descrepancies:

Using the noise measurements with different DC current levels, the transimpedance for each frequency can be reconstructed.

Does this indicate the satiration by the white light???

- The TF measurement shows consistent mag&phase relationship at the resonance (c.f. LISO fit).
So this steep resonance is not an artifact by a noise or glitch but the real structure of the electronics.

- The TF measurement has been done with the photocurrent of ~0.3mA, while the transimpedance measurement
with the white light illumination has the practical effect only when the DC photocurrent is larger than 1mA
because of the circuit noise. Does this higher photo current affected the resonance?

- The off-resonant transimpedance agree with the TF measurement as far as we can see with those measurements.
This may mean that the actual resonant structure has been affected in the white light measurement.
(i.e. not the saturation of the RF opamp which causes the change of the gain at any freq.)
Is the above mentioned higher DC current causing the change of the diode capacitance or other property of the diode or the inductors???

Attachment 1: REFL165_test_111014_KA.pdf

Attachment 2: REFL165_transimpedance2.pdf

5672

Sat Oct 15 17:06:20 2011

REFL165 was installed on the AP table last night.

Meanwhile I found the DC power level at the REFL PDs were 0.8~1.2V if the PRM is aligned and the IFO is not locked.
This corresponds to 16~24mA (20~30mW). This is too big.

The HWP of the REFL path were adjusted so that we have 6~10mA (8~12mW) on each PDs.

5678

Mon Oct 17 11:40:44 2011

REFL165 removed from the table

REFL165 removed from the table for the C(V) test

5681

Mon Oct 17 22:20:42 2011

REFL165 removed from the table

Quote:

REFL165 removed from the table for the C(V) test

The PD was returned on the table.

The C(V) compensation path was modified and the change of the resonant freq was cancelled.
A more precise analysis comes later.

5684

Tue Oct 18 04:04:27 2011

measurement of sensing matrix : touchy SRM

I made some attempts to measure the sensing matrix of the central part.

I could measure the matrix in the PRMI configuration but wasn't able to measure the matrix in the DRMI configuration.

=> I will report the result of the PRMI sensing matrix tomorrow.

The main reason why I couldn't lock DRMI was that the suspensions were touchy and especially the SRM suspension wasn't good.

Some impacts due to the feedback during the lock acquisition completely kicks SRM away.

The watchdogs' RMS monitor on SRM easily rang up to more than 10 counts once the acquisition started.This is quite bad.

Also the stability of the PRMI lock was strongly depending on the gains of the PRM oplevs.

I guess I have to revisit the vertex suspensions more carefully (i.e. f2a coupling, actuator output matrix, damping gains, input matrices, oplev filters)

otherwise any LSC works in the vertex will be totally in vain.

5685

Tue Oct 18 10:04:41 2011

REFL165 removed from the table

The original REFL165 had ~50MHz/A dependence on the DC photocurrent.
The resistr R21, which was 2670 Ohm contrary to the original drawing, was replaced to 532 Ohm
to increase the feedforward gain by factor of 5.

The resulting dependence is reduced to ~0.5MHz/A although it has Q reduction of ~20% at 6mA.

Some concerns:

These transfer functions were measured between TEST IN and RF OUT while the diode was illuminated with the white light from a light bulb.

There looks some thermal effect on the resonant freq. If the white light illumination is suddenly removed, the bias compensation
is immediately removed but the resonance takes some time (~min) to come back to the original freq.

I am afraid that the light bulb gave too much heat on the surrounding PCB and lead unnecesarily high level dependence of the resonant freq on the DC current.

Or, if this thermal effect comes from the power consumption on the diode itself, we need to characterize it for aLIGO.

In order to check this, we need a test with the 1064nm illumination on the diode in stead of the light bulb.

Attachment 1: REFL165_original.pdf

Attachment 2: REFL165_new.pdf

Attachment 3: REFL165_schematic_111017_KA.pdf

5703

Wed Oct 19 17:21:16 2011

Modification on the RFPD interface cards

I have modified all of the three RFPD interface cards to be enabled permanently.
This prevents an accidental disabling caused by a stray voltage of the logic input (or whatever),
which was reported in multiple occasions by Anamaria and me.

The logic ICs (74LS04) for buffering of the EPICS switches were removed by 14pin sockets with additional wires soldered.
The modification shorts the inputs to the second logic chips, resulting in the permanent enabling of the PD circuit.

Attachment 1: D990543-B_mod.pdf

5709

Thu Oct 20 04:47:37 2011

clipping search round 1

[Koji / Kiwamu]

We tried finding a possible clipping in the vertex part.

We couldn't find an obvious location of a clipping but found that the recycling gain depended on the horizontal translation of the input beam.

We need more quantitative examination and should be able to find a sweet spot, where the recycling gain is maximized.

(what we did)

+ locked the carrier-resonant PRMI.

+ with IR viewers we looked at the inside of ITMX, ITMY and BS chambers to find an obvious clipping.

=> found two suspicious bright places and both were in the ITMY chamber.

(1) POY pick off mirror : looked like a small portion of a beam was horizontally clipped by the mirror mount but not 100% sure whether if it is the main beam or a stray beam.

(2) The top of an OSEM cable connectors tower : although this is in the way of the SRC path and nothing to do with PRC.

+ Made a hypothesis that the POY mirror is clipping the main beam.

+ To reject/prove the hypothesis we shifted the translation of the incident beam horizontally such that more beam hits on the suspicious mirror

+ Realigned and relocked PRMI.

=> Indeed the recycling gain went down from 6 to 0.8 or so. This number roughly corresponds to a loss of about 50%.

However the MICH fringe still showed a very nice contrast (i.e. the dark fringe was still very dark).

Therefore our conclusion is that the POY mirror is most likely innocent.

5743

Wed Oct 26 20:30:47 2011

Katrin

POX11 and POP55 installed

[Katrin,Jenne]

RF photo diodes POP55 and POX11 are installed. The beams are aligned to the photo diodes.

PD	DC out dark	DC out bright	light power	calculated DC output
POX11	0.1mV	1.3mV	0.09mW	3mV
POP55	35mV	55mV	3 to 4 µW	25mV

I used 0.7 A/W for the response and 50V/A for POP55 according to elog page #4576.

To install the third RF photo diode we need to order a plano-convex lens with a focal length of 750 or

maybe even better 1000

5744

Wed Oct 26 23:03:03 2011

RF distribution box : two more 55MHz available

The RF distribution box has been modified so that it generates two more 55 MHz LO signals.

After the modification I put the box back in place.

Then I checked the MICH and YARM locking quickly as a working test of the distribution box and it is working fine so far.

I will update the diagram of the RF distribution box (#4342) tomorrow.

(Motivation)

Since we newly installed POP55 (#5743) an LO signal was needed for the demodulation.

However the RF distribution box didn't have any extra LO outputs.

Therefore we had to make a modification on the RF distribution box so that we can have a 55MHz LO signal for POP55.

Eventually I made two more 55MHz outputs including one spare.

(Modification)

The box actually had two extra output SMAs which had been just feed-thru connectors on the front panel without any signals going through.

In the box the modules consist of two categories; the 11MHz system and 55MHz system. I modified only a part of the 55MHz system.

The modification was done in this way:

* split two branches of 55MHz into four branches by installing two new power splitters (ZMSC-2-1).

* made and installed some SMA cables whose length were adjusted to be nicely fit in the box.

* readjustment of the RF levels to 0-2 dBm at the outputs by replacing some attenuators.

* checked the signals if all of them were happily coming out or not.

Also I found that the POX11 and POY11 demod boards were connected to the whitening filters in a wrong way.

The I and Q signals were in a wrong order. So I corrected them so that the upper inputs in the whitening filter is always the I signal.

(RF levels on 55MHz LO outputs)

Since the demod board requires a certain level of the RF signal as as LO, the LO signals have to be 0-2 dBm.

Here are the RF level in each 55MHz output after the adjustment of the level.

AS55 = 0.76 dBm

REFL55 = 0.76 dBm

POP55 = 0.79 dBm

spare = 0.83 dBm

Those numbers were measured by an oscilloscope and the oscilloscope was configured to measure the rms with the input impedance matched to 50Ohm.

In the measurement I used the actual input seed 55MHz signal from the RF generation box to drive the distribution box.

5746

Thu Oct 27 16:09:37 2011

RF distribution box : two more 55MHz available

The diagram of the RF distribution box has been updated according to the modification ( #5744).

Both pdf and graffle files are available on the 40m svn : https://nodus.ligo.caltech.edu:30889/svn/trunk/suresh/40m_RF_upgrade/

Here shows the latest version of the diagram.

Quote from #5744

I will update the diagram of the RF distribution box (#4342) tomorrow.

5747

Thu Oct 27 18:00:38 2011

Offsets in LSC signals due to the RFAMs : Optickle simulation

The amount of offsets in the LSC signals due to the RFAMs have been estimated by an Optickle simulation.

The next step is to think about what kind of effects we get from the RFAMs and estimate how much they will degrade the performance.

(Motivation)

We have been having relatively big RFAM sidebands (#5616), which generally introduce unwanted offsets in any of the LSC demodulated signals.

The motivation was that we wanted to estimate how much offsets we've been having due to the RFAMs.
The extreme goal is to answer the question : 'How big RFAMs do we allow for operation of the interferometer?'.

Depending on the answer we may need to actively control the RFAMs as already planed (#5686).

Since the response of the interferometer is too complicated for analytic works, so a numerical simulation is used.

(Results : Offsets in LSC error signals)

Figure: Offsets in unit of meter in all the LSC demodulated signals. Y-axis is the amount of the offsets and the X-axis represents each signal port.

In each signal port, the signals are classified by color.

(1) Offsets in the PRCL signal. (2) Offsets in the MICH signal. (3) Offsets in the SRCL signal.

Roughly the signals showed offsets at a 0.1 nm level.

The numerical error was found to be about 10^-10 nm by running the same simulation without the AM sidebands.

Here is a summary of the amount of the offsets:

	offsets [nm] (1f signal port)	offsets [nm] (3f signal port)	biggest offsets [nm] (signal port)
PRCL	0.3 (REFL11)	0.2 (REFL33)	1 (REFL55)
MICH	0.00009 (AS55)	0.8 (REFL33)	7 (POP11)
SRCL	0.1 (REFL55)	0.1 (REFL165)	40 (POX11)

In the SRCL simulation REFL11I, REFL11Q, POP11I, POP11Q and POX11I didn't show any zero crossing points within 100 nm range around the resonance.

It is because that the SRCL doesn't do anything for the 11MHz sidebands. So it is the right behavior.

However POX11 was somewhat sensitive to the SRCL motion and showed a funny signal with a big offset.

(Simulation setup)

I applied the current PM/AM ratio according to the measurement (#5616, #5519)

The modulation indices used in the simulation are :

+ PM index in 11MHz = 0.17

+ PM index in 55MHz = 0.14

+ AM index in 11MHz = 0.17 / 200 = 8.5x10^-4

+ AM index in 55MHz = 0.14 / 200 = 7.0x10^-4

Note that the phases of the AM and PM sidebands are the same.

For clarity, I also note the definition of PM/AM ratio as well as how the first order upper sideband looks like.

The optical parameters are all at ideal length although we may want to check the results with more realistic parameters:

+ No arm cavities

+ PRCL length = 6.75380

+ SRCL length = 5.39915

+ Schnupp asymmetry = 3.42 cm

+ loss in each optic = 50 ppm

+ PRCL = resonant for 11 and 55MHz

+ MICH = dark fringe

+ SRCL = resonant for 55 MHz

The matlab script will be uploaded to the cvs server.

Quote from #5686

8. In parallel to those actions, figure out how much offsets each LSC error signal will have due to the current amount of the RFAMs.

=> Optickle simulations.

5752

Fri Oct 28 03:42:50 2011

ITMX table needs to be refined

(POX)

The POX beam had been 80% clipped at a black glass beam dump of the POX11 RFPD.

I steered the first mirror in the POX path to fix the clipping. Then the beam was realigned onto the RFPD.

However the beam is still very close to the black glass, because the incident angle to the second mirror is not 45 deg .

We need to refine the arrangement of the POX11 optics a bit more so that the beam will never be clipped at the black glass.

(POP)

The POP optics also need to be rearranged to accommodate one more RFPD.

Additionally Rana, Suresh and I discussed the possible solutions of POP22/110 and decided to install a usual PD (PDA10A or similar) instead of a custom-made.

So a plan for the POP detectors will be something like this:

+ design an optical layout.

+ buy a 2 inch lens whose focul length is long enough (#5743)

+ rearrange the optics and install POP22/110

+ lay down a long SMA cable which sends the RF signal from POP22/110 to the LSC rack.

+ install a power splitter just before the demod board so that the signal is split into the 22MHz demoad board and 110MHz demod board.

=> make sure we have a right splitter for it.

+ install a band pass filter after the power splitter in each path.

=> A 22MHz band pass filter is already in hand. Do we have 110MHz band pass filter somewhere in the lab ?

The picture here shows the latest configuration on the ITMX table.

Quote from #5743

RF photo diodes POP55 and POX11 are installed. The beams are aligned to the photo diodes.

5753

Fri Oct 28 04:57:00 2011

POX11 demod board broken

The POX11 demodulation board is broken. It needs to be fixed in the daytime tomorrow.
It only outputs the Q signal and nothing is coming out from the I output.

(Some stuff checked)
[OK] ADCs
[OK] Whitening filters looked fine. Their gains were controllable from EPICS.
[OK] Connection between the POX11 RFPD and demodulator box
[OK] The Q signal showed the PDH signal of the X arm with an amplitude of about 200 counts, which almost is the same as that of POY11.

[NOT GOOD] The I signal from the demod board
[OK] Outputs cables, which send the I and Q signals from the demod board to WFs are fine.

(Test on the POX11 demod board)
As usual, a test signal whose frequency is shifted by a little bit from that of LO was injected to the RF input of the board to see if the circuit is working.
The I signal didn't show up and there were no signals even in the monitor LEMO output.
Something is wrong in the I signal demodulation path on the circuit board.

Here is an actual time series of the I and Q signals in dataviewer. The I signal outputs just junk while the Q showed a nice sine curve.

5754

Fri Oct 28 05:17:13 2011

locking activity : PZT1 is still railing

Status update on the LSC activity:

To see how good/bad the beam pointing is, I locked the Y arm with POY11.
Then I ran the ASS servo to automatically correct the alignment of the ITMY and ETMY suspensions and also the beam pointing.
The result is that the PZT1_X is still railing to the negative side.

Due to it the transmitted light from the Y arm is about 0.6 or so which is supposed to be 1 if the beam pointing is perfect.
The EPICS value of PZT1_X is at the minimum of -10 and the ASS servo tried to push it more negative side.

Tomorrow night I will intentionally introduce offsets in the MC suspensions to avoid the railing.

The goal will be a scan of the incident beam while measuring the recycling gain.

5760

Fri Oct 28 20:39:19 2011

MIrko

RFAM monitor in place. ( Uncalibrated ) EPICS troubles

{Suresh, Jamie, Mirko]

We adapted the Stochmon box to include LP filters at 1.8Hz behind the RMS parts.
Then measured the RMS signals for different RF signal levels at 11.0.65, 29.5, 55.325MHz provided by a RF freq. generator.
As you can see in the data below the suppression of the BP filters of neighboring frequencies is only 35-35dB in power (see also manufacturer specs).

We therefor want to substract crosstalk, by calculating it out. We decided to use C-code in CDS. No computer crashing this time :)

We however ran into the problem that the RMS signal channels are acquired by the slow (EPICS) maschine c1iool0. Channels are (C1:IOO-RFAMPD_33MHZ , -"-133MHZ, -"-166MHZ) and we could not access those in the CDS c1ioo model. Using the EpicsIn block we got an CA.Exception stating that the variable was hosted on multiple servers. We then tried to use the EzcaRead to access the variables. Got an compile error, about the compiler not beeing able to connect all parts. It seems that the EzcaRead left behind a "ghost" part in the model (something with M1:SYS-FOO_BAR which is the default naming of the EzcaRead block) even after we deleted that block. We toyed around with the /opt/rtcds/caltech/c1/chans/daq/C1EDU_IOO.ini and /cvs/cds/caltech/target/c1iool0/ioo.db files. We tried to uncomment the "old" (33,133,166) channels there to get rid of the conflict, but that didn't work.

We want to write the outputs to C1:IOO-RFAMPD_11MHZ , -"-29MHZ, -"-55MHZ EPICS channels.

We had to get the model back from the svn to get it running again.

Attachment 1: MC_DC11MHz.m

Pwr=[-60,-55,-50,-45,-40,-35,-30,-25,-20,-10,-5,0,5,10]';
Voltage11=[2.12,2.10,2.03,1.93,1.83,1.71,1.59,1.47,1.35,1.10,0.97,0.85,0.71,0.61]';

Voltage11=spline(Pwr,Voltage11,linspace(-60,10,15));
PwrSmooth=linspace(-60,10,15);

Voltage29=[2.14,2.14,2.14,2.14,2.14,2.14,2.13,2.12,2.09,1.94,1.84,1.73,1.61,1.49];
Voltage29=spline(Pwr,Voltage29,linspace(-60,10,15));

Voltage55=[2.16,2.16,2.16,2.16,2.16,2.16,2.16,2.15,2.14,2.13,2.10,2.04,1.94,1.83];

... 5 more lines ...

Attachment 2: MC_DC29MHz.m

Pwr=[-60,-55,-50,-45,-40,-35,-30,-25,-20,-15,-10,-5,0,5,10]';
Voltage11=[2.16,2.16,2.16,2.16,2.15,2.16,2.15,2.13,2.10,2.03,1.93,1.81,1.70,1.58,1.46]';

Voltage29=[2.12,2.10,2.03,1.93,1.83,1.70,1.59,1.47,1.34,1.22,1.09,0.97,0.84,0.71,0.61]';

Voltage55=[2.16,2.15,2.16,2.16,2.15,2.15,2.14,2.10,2.0,1.97,1.97,1.77,1.65,1.50,1.37]';

%%  Example 55MHz inj.

Voltage11=[2.00];

... 21 more lines ...

Attachment 3: MC_DC55MHz.m

Pwr=[-60,-55,-50,-45,-40,-35,-30,-25,-20,-15,-10,-5,0,5,10]';
Voltage11=[2.16,2.16,2.16,2.16,2.16,2.15,2.15,2.15,2.15,2.15,2.12,2.09,2.00,1.89,1.78]';

Voltage29=[2.14,2.14,2.14,2.13,2.14,2.13,2.11,2.06,1.98,1.88,1.76,1.64,1.52,1.40,1.27]';

Voltage55=[2.14,2.11,2.05,1.96,1.85,1.73,1.61,1.48,1.36,1.23,1.10,0.98,0.84,0.71,0.61]';

plot(Pwr,Voltage55)

%%

... 17 more lines ...

Attachment 4: RFAMPD.c

double x;
double y;
double z;

double temp1;
double temp2;

double Corrx;
double Corry;
double Corrz;

... 49 more lines ...

5762

Sat Oct 29 05:50:44 2011

MC suspensions misaligned to avid railing for PZTs

I have shifted the alignment of the MC suspensions such that the PZT won't rail.

Since I didn't care of the spot positions on the MC mirrors, currently they are terribly off from the centers.

After the shift, I realigned the Stochmon PD again.

The attachments below shows the alignment of MC and PZTs before shifting the just for a record

Quote from #5754

Tomorrow night I will intentionally introduce offsets in the MC suspensions to avoid the railing.

The goal will be a scan of the incident beam while measuring the recycling gain.

5763

Sat Oct 29 22:57:03 2011

Mirko

AM modulation due to non-optimal SB frequency

[Kiwamu, Mirko]

Non-optimal 11MHz SB frequency causes PM to be transformed into AM.
m_AM / m_PM = 4039 * 1kHz / df , with df beeing the amount the SB freq. is off.

Someone might want to double check ths.

Attachment 1: IMC.pdf

5773

Mon Oct 31 21:46:32 2011

Dependence of Recycling gain on incident beam pointing

I horizontally swept the translation of the incident beam in order to investigate a possible clipping in Power-recycled Michelson (PRMI).

The recycling gain of PRMI depended on the beam pointing but it did't improve the recycling gain.

I guess the amount of the entire shift I introduced was about +/- the beam diameter = +/- 5 mm or so.

Within the range of about +/- 5mm in the horizontal beam translation I didn't find any obvious sign of a clipping.

(Measurement)

This is the procedure which I did:

(1) Some amount of offsets were introduced on MC2 in both PIT and YAW such that the PZT1 won't rail (#5762).

=> Every time when I introduced the offset I realigned the zig-zag mirrors on the PSL table to maintain the high transmissivity of MC.

(2) Fine tuning of the MC offsets so that the PZT1_X EPICS value becomes almost zero when the beam is aligned down to the Y arm.

=> 0.523 in C1:ASC_PZT1_X became a point where the coupling of the beam into the Y arm was maximized.

=> Last time the direction which we investigated was the positive side from this zero point (#5709) in PZT1_X.

(3) Aligned MICH by steering BS.

(4) Locked PRMI with carrier resonating and aligned PRM to maximized the power recycling gain which was obtained from POYDC.

(5) Translated the beam pointing

=> First I shifted PZT1_X by a wanted amount.

=> Then I locked the Y arm and realigned PZT2_X by maximizing the Y arm transmission.

This procedure should give us a pure translation on the incident beam.

(6) Repeated the same procedure (3) through (5) in each PZT1 position.

(Results)

Here shows the measured recycling gain and the power reflectivity of PRMI as a function of the beam pointing.

Upper plot : measured recycling gains (Red) observed maximum values (Black) measured values on average.

Lower plot : measured power reflectivity of PRMI (Blue) observed minimum values (Black) measured values on average.

As shown in the plots the recycling gain could go up to 8 at some points.

As the PZT went away from 0 it decreased and eventually became about 3 in each side.

The reflectivity showed the minimum value of 0.4 when the PZT1 was at -1 in EPICS value.

One hypothesis to explain this plot can be that : we are just seeing the effect of the incident beam misalignment.

5774

Tue Nov 1 13:41:38 2011

Mirko

AM modulation due to non-optimal SB frequency

Quote:

[Kiwamu, Mirko]

Non-optimal 11MHz SB frequency causes PM to be transformed into AM.
m_AM / m_PM = 4039 * 1kHz / df , with df beeing the amount the SB freq. is off.

Someone might want to double check ths.

Actually there was an error.

For 11MHz it is:
m_AM / m_PM = 2228 * 1kHz / df

For 55MHz:
m_AM / m_PM = 99.80 * 1kHz / df

see PDF

Attachment 1: IMC.pdf

5788

Wed Nov 2 19:32:20 2011

[Steve / Kiwamu]

The POP22/110 RFPD has been installed. It is PDA10A from Thorlabs instead of the usual home-made RFPD.

For an RF cable we rerouted one of the spare Heliax cables for it.

The cable is the one which used to be served for the 166MHz ASC wavefront sensors, picking up the RF source signal at 1X2 and sending it to the LSC rack.

- - Remaining tasks - -

+ Fine alignment

+ Connection at the LSC rack

+ Update of the table diagram

Quote from #5783

They were traced and labeled. One goes to 1X2 and the other to AS-ISCT. They are Andrew Heliax 1/4" od. made by CommScone, model number FSJ1-50A

5794

Thu Nov 3 14:25:52 2011

PDA10A as POP22/110 : too small signal

It turned out that the signal was too small with PDA10A to detect the 22 and 110 MHz RF sidebands.

The DC output coming out from it was about half mV or so (corresponding to few uW in laser power) when the PRCL was locked to the carrier.

This is because PDA10A is a silicon detector which is more sensitive to visible light than IR.

The reason we chose PDA10A was that it has relatively a large diode size of 1 mm in diameter.

However according to the data sheet the responsibility at 1064 nm is about 0.05 A/W which is sad.

I will replace it by PDA10CF, which is made from InGaAs and supposed to have 10 times bigger responsibility.

Though the diode size will be half mm in diameter, which may require another strong lens in front of it.

Quote from #5788

The POP22/110 RFPD has been installed. It is PDA10A from Thorlabs instead of the usual home-made RFPD.

+ Fine alignment

5796

Thu Nov 3 16:31:47 2011

PDA10CF as POP22/110 : better

The POP22/110 RFPD has been replaced by PDA10CF. As a result the 22 and 110 MHz signals became detectable.

However the signal level maybe too low according to a quick look with an RF spectrum analyzer.

The level at 22 and 110 MHz were both approximately -70 dBm although these values were measured when the central part was freely swinging.

Perhaps we need to amplify the signals depending on the actual SNR.

Also I have updated the optical tables' wiki page :

http://blue.ligo-wa.caltech.edu:8000/40m/Optical_Tables

Quote from #5794

I will replace it by PDA10CF, which is made from InGaAs and supposed to have 10 times bigger responsibility.

5801

Thu Nov 3 18:41:36 2011

POX11 demod board : haven't been modified yet

I pulled out the POX11 demod board and found the power splitter on the board hadn't been modified yet.

I am going to replace the splitter which had been made with a hand-wounded coil because it can work only at a specific tailored frequency.

Quote from #5753

The POX11 demodulation board is broken

5802

Thu Nov 3 19:58:18 2011

POX11 demod board : modification done

The modification on the POX11 demod board has been successfully done.

I followed the procedure which had been posted in a past entry (#4554).

The home-made splitter was replaced by PSCQ-2-51W, which has a relatively wide band of 5 - 50 MHz.

The usual orthogonality adjustment will be done in the daytime.

The attached snapshot was taken when an sinusoidal RF signal with a slight frequency offset from LO was injected to the RF input.

It is clear that the I and Q output show healthy signals (i.e. almost the same amplitude and 90 deg phase difference.)

Quote from #5801

I am going to replace the splitter which had been made with a hand-wounded coil because it can work only at a specific tailored frequency.

5804

Fri Nov 4 00:13:24 2011

XARM locked with POX11

XARM lock was achieved by POX11_I

Summary:

- The whitening gains of POX11_I and Q are 42dB so that POX11_I have the same amplitude as AS55_I

- The demod phase of POX11 was adjusted to eliminate the PDH signal from the Q phase. The phase is -100.5deg.

- In order to lock the XARM with POX11_I_ERR, I had to increase the trigger threshold from 0.1 to 0.2 as the arm was
kicked with the threshold of 0.1.

Method

- Lock the X arm with AS55_I at the XARM configuration.

- Adjusted POX11 demod phase so that POX11_Q is minimized.

- POX I&Q whitening gains were adjusted. When they are 42dB, POX11_I_ERR and AS55_I_ERR have almost the same signal amplitude.
(In reality, POX11_I_ERR has +1dB larger amplitude.)

- Adjusted POX11 demod phase again with better precision.

- Measured transfer function between AS55_I_ERR and POX11_I_ERR. As the sign was opposite, the demod phase was -180deg flipped.

- Tried to lock the arm with POX11_I_ERR. It did not acquire the lock. The arm looked kicked by the servo.

- Increased the trigger threshold from 0.1 to 0.2. Now the arm is locked with POX11_I_ERR.

Attachment 1: POX11.pdf

5806

Fri Nov 4 05:24:56 2011

offset introcuded in MC and IFO-configure script modified

[Offsets in MC]

I have introduce an offset in MC2 PIT because the PZT1 again started railing.

Right now the PZT1 EPICS value is within the range happily.

Please keep this MC eigen axis as a nominal configuration.

[IFO-configure script]

I have modified the IFO configure scripts such that XARM and YARM are locked with POX11 and POY11 respectively.

A big advantage in use of POX and POY is that we don't need to misalign ITMs when we align each arm.

Those scripts are now available from the C1IFO_CONFIGURE screen as usual.

5812

Fri Nov 4 15:26:54 2011

I moved the place where we take the OAF Degree of Freedom signals from - now it's the error point rather than the feedback for DARM, CARM, MICH, PRCL, SRCL, XARM and YARM. I didn't do anything to MCL.

While trying to compile, there was something wrong with the lockins that were there...it complained about the Q OUTs being unconnected. I even reverted to the before-I-touched-it-today version of c1lsc from the SVN, and it had the same problem. So, that means that whomever put those in the LSC model did so, and then didn't check to see if the model would compile. Not so good.

Anyhow, I just terminated them, to make it happy. If those are actually supposed to go somewhere, whoever is in charge of LSC lockins should take a look at it.

Also, as Mirko mentioned in the previous elog 5811, we wanted to calculate the effect on the MC without actuating, so we put in a new summing point and a filterbank so we have testpoints.

LSC model recompiled.

OAF model recompiled.

FB restarted because of the new channels added to OAF.

5832

Mon Nov 7 15:15:21 2011

Quote:

Anyhow, I just terminated them, to make it happy. If those are actually supposed to go somewhere, whoever is in charge of LSC lockins should take a look at it.

Also, as Mirko mentioned in the previous elog 5811, we wanted to calculate the effect on the MC without actuating, so we put in a new summing point and a filterbank so we have testpoints.

LSC model recompiled.

OAF model recompiled.

FB restarted because of the new channels added to OAF.

After Rana pointed out the errors of our ways, we reverted all of these changes.

5833

Mon Nov 7 15:43:25 2011

Quote:

Anyhow, I just terminated them, to make it happy. If those are actually supposed to go somewhere, whoever is in charge of LSC lockins should take a look at it.

This was totally my fault. I'm very sorry. I modified the lockin part to output the Q phase, and forgot to modify the models that use that part appropriately. BAD JAMIE! I'll check to make sure this won't bite us again.

5849

Wed Nov 9 14:49:07 2011