IOO QPDs tested in dark, lighted and open PSL enclosure. The created temperature change 0.03 C has  effect on monitoring  in pitch.

 Atm1,  all lights off 10 min, PSL enclosure lights on  10 min, all lights off 15 min, open  door # 11 at north east corner of enclosure ( HEPA filters are running at 30V ) for 10 min, closed-dark enclosure 15 min

              dark 10, lighted 10, dark 15, open-dark 10 and closed-dark 15 minutes

Atm2, Pitch drift of 24 hours does not recover

I looked at IOO QPDs again. QPD_POS was clamped by one screw. Dog clamp was added on the unclamped side.

QPD_ANG chassis has no isolation to optical table..._POS has.  QPD_ANG  base was tightened also.

Both QPDs moved a little bit but I did not centered them.  The spot sizes are 2-3 mm  They should be smaller.

How ever, we still can not explane the pitch movement of the IOO beam

Razor beam dumps were labeled at the AP table.

The 40m roof was cleaned from leafs this morning.

 IOO pointing is drifting in pitch. I'd like to use a QPD instead of the paper target to see if the Innolite output is stable. The idea is to move temporarily IOO-QPD_POS to  this location

 Three good days of IOO pointing: Friday, Sat and Sun    What was changed?  May be the clamping on Friday?

IOO vertical changes recovering as tempeture. IP is clipping at plastic enclosure of ETMY

NOTE: ANTS at the PSL optical table.  I will mop with chemicals tomorrow if we see more.

 I do like to move IOO-QPD_POS temporarily to see that the feedback has anything to do with with the pointing.

GariLyn is using our green light on the west side of the PSL table. The green PDA36As were moved and the HEPA turned up to 60V

The 2W Innolight was off for 4 hours.

CVI broadband AR coating was measured at the PSL-enclosure table around 9-10am today. The 2W Innolight first PBS  S polarization beam was used with an other 1/2 wave plate and PBS.

W2-PW1-1004-C-633-1064-0   This 0.045" thick window has 0.7- 0.8 % reflected beam on each sides at 5 degrees of incidence, P polarization.

The specification is  R avg <0.5 % per surface at 0 degree

Rana wants The device would be useless with such a high R, but R 0.1% is OK so I will get V coating.

 CVI V-AR coating at 1064 nm, 0 degree,  catalog item is R< 0.25% on each sides,

 R <0.1 % is custom at much higher prices.

This custom order should go with other  orders that has similar need.

From CVI: 5-6-2014

I checked the trace info on the W2-PW1-1004-C-633-1064-0, BBAR coated window that you received.  It is side 1, 0.42%R & side 2, 0.53%R @ 1064nm.  And with the shift, I’m not too surprised you ended up with 0.7%.  A V coat would start with <0.25% (and more typically coming in at ~0.1%) per surface.  As far as stock options, I have a 1”dia x 4mmT, fused silica window that is recorded as side 1, R=0.09 and Side 2, R=0.08% @ 1064.  Is this too think or will it work for you?

The PMC runs out of range sometimes due to the daily temperature swing. The voltage swings up after sunset and then starts to swing down before sunrise. So when you relock the PMC at the beginning of the locking night, the mnemonic from the PMC is:

Sun Go Low, Lock Me Voltage Low.

 Tonight I noticed that the drop in PMC transmission was ~1V, more than the usual of ~0.5V from the daily drift.

While re-aligning on the table, I noticed that the misalignment was not from either of the steering mirrors; i.e. I has to walk them both to get the alignment back. This implies that the misalignment is generated far upstream. Maybe the the laser itself is moving. We need some updates from Steve's laser misalignment tracker.

I'd like to replace the paper target with IOO -QPD_POS so we can log it.

PMC has been unlocked for ~4hrs, not sure why. It's servo gain was down at -10dB...

Relocked with transmission of .76V, MC locks fine with WFS, transmission of 15.5k.

I came in and PMC transmission was at 0.5V, and ETMX was swinging around a lot, (LSC mode was on). 

Turning off oplevs let ETMX calm down. I realigned the PMC to 0.82V. 

MC wouldn't relock, it looked misaligned in pitch and yaw on MC camera.

I've touched the alignment, and gotten the reflection below 0.5, but it unlocks periodically, spot positions aren't great, and turning on WFS throws it out of alignment. ughhhhh

Also, while I was working on the PSL table, I heard noise that sounded like a bearing rolling around.  I suspected the HEPAs, since the one on the north east corner of the table has a problem when it's turned up high (we've known about this for a long time), however turning off the HEPAs didn't affect the noise.  The noise is strongest near the back of the PSL controller on the shelf above the table, and the PSL controller box is vibrating.  So, I suspect that the fan on the PSL controller box is about to give out.

EDIT:  To clarify, I mean the Innolight's controller.

 The bearing is chirping in the back of the 2W Innolight laser controller. It is loud enough to hear it. I placed 4 soft  rubber feet under the controller to avoid shaking other things on self.

The HEPA filter bearing becomes noisy at 50V

 Keep it at 20V for low noise

  The aging of the laser came up when the noisy bearing showed.  ~10% down in in 4 years. That is pretty good.

I would like to measure the switching time of the AOM. So I have disconnected the modulation input to the AOM that comes from the ISS. I have also turned OFF the SR560's and the AWG that belong to ISS. 

Pics and cable connections of the state in which the ISS setup was left at, will be updated soon.

The window is at the north west corner of the  PSL enclosure.

The 1 mm thick BK7 window is AR coated both side R <0.08%,  W2-PW1-1004-1064-0

The PZT stack is 0.75" OD, 0.25" thick with  ~ 6 mm ID,  motion range 2.5 micron at 200V

Soft silicon rubber isolation.

RXA: This is the opto-mechanical phase shifter that Steve has built for diagnosing scattered light problems. We put it into the reflected light path of any of the cavities and see if it can move the scattering noise from DC up to a higher frequency. e.g.:

The paper on this from GEO

I installed a fast PDA10CF along the path of a leaking beam from one of the steering mirrors that direct the main beam to the PMC. This beam was dumped to a razor blade. I removed the razor blade and installed a Y1 to steer this beam through a lens on the PD.

Pics of the layout post-installation will be updated.

Also, I tested the AOM by giving it 0-1V modulation input from the AWG. This has been disconnected after the test. So everything should be as it was pre-testing.

Edit/manasa/ Data has not been fit correctly in here. A proper fit will follow this elog.

Proper fits and numbers are here :elog

Earlier last week I had tried to measure the AOM ringdown and concluded I could not make one.

I was proved wrong and I was able to make a measurement. I am still not sure why I was not able to make the measurement earlier with the very same settings and configuration.

What I did:

I gave the AOM a 0-1V modulation input using the signal generator (50 ohm feedthrough bnc was used to impedance match the AOM driver's modulation input). For the measurement here I used a 1Hz square wave. I used a 300MHz oscilloscope to look at the falling edge of the ringdown PD output installed.

I recorded a few ringdown samples. To get a quick number, I fit one such sample to find the AOM switching time as 1.48us (Plot attached). 

I moved stuff on the PSL table to accommodate the PMC ringdown setup.

I used the beam that leaks from the steering mirror at the PMC transmission that was dumped to a razor blade dump. I installed a Y1 to steer the beam to the ringdown PD. Power in the beam 75mW.

Results are in here elog 

The PMC local oscillator is going a little weird dying.  We need to check out why the level is fluctuating so much.

Here's a 6 month plot, where you can see that the lower level keeps getting lower (y-axis is dBm):

This LHO entry from 2008 shows where we first discovered this effect. As Rick Savage and Paul Schwinberg later found out, the ERA-5SM+ amplifier slowly degrades over several years and was replaced for both of the eLIGO interferometers. We have spares in the Blue box and can replace this sometime during the day.

Our PMC LO is made by this obsolete crystal oscillator circuit: D000419. There are many versions of this floating around, but they all have the ERA-5 issue.

It seems that there is no better chip in MiniCircuits line-up with the same form factor.
ERA-5 is the most powerful one in the ERA (or MAR) series.

If the output is ~0dBm we have MAR-6SM in stock. But I suspect that ERA-5 was driven at the power level close to its saturation (~18dBm).

If we allow different form factors, we have GVA-** or GALI-** in the market and also in the blue tower, in order to gain more performance margin.
If it is difficult to apply them, I would rather use another ERA-5 with enhanced heat radiation.

I'm sure that Downs has EAR-5 replacement.

 I am guessing that 75 mW will burn / destroy any Thorlabs PD. I hope that mW is supposed to be uW.

Koushik and Koji try to fix the PMC oscillator issue. So we remove the module from the rack.
This means we don't have the PMC transmission during the work.

Koushik replaced an ERA-5 in the PC path. We put the module back to the rack and found no change.
The epics LO level monitor monitor is still fluctuating from 6~11dBm. We need more thorough investigation
by tracing the signals everywhere on the board.

Despite the poor situation of the modulation, PMC was locking (~9PM). Rana suspect that the PMC demodulation
phase was not correctly adjusted long time. 

Koushik has the measured power levels and the photos of the board. I'll ask him to report on them.

 After the ERA-5 was replaced (see Koushik elog) we relocked the PMC.

The new LO level going into the PMC servo card is +11.5 dBm. The LO mon on the PMC card reads 9 dBm and seems so flat I now suspect the monitor circuit.

I also measured the RF drive to the EOM as a function of C1:PSL-PMC_RFADJ on the Phase Shifter screen.

The phase shifter slider gives ~75 deg/V in phase shift of the RF out to the EOM. I tried to optimize the loop gain quickly using the fluctuations in the reflected power. The loop oscillates at high frequency with the slider at 21 dB and also at 9 dB. So I set the gain at +14 dB. Needs to be optimized correctly in the daytime.

 Updates from Koushik:

The power levels measured (before and after relacement of ERA-5) are as follows:

LO to Servo : Vout = 2.3 Vpp / Pout = 11.21 dBm at f = 35.5 MHz

RF to PC   :   Vout = 354 mVpp / Pout = -5.1 dBm at f= 35.5 MHz

The measurements were done using an oscilloscope with 50 ohms load impedance. Unfortunately the photos are not available from the camera.

 It was ~7.5mW and measured ~2V at the PD output (given its range 0-5V ) on the oscilloscope . So PD is safe !

The first step is

The second uptick (In Nov 14, 2013) is when I removed a 3 dB attenuator from the LO line. Don't know why the decay accelerates after that.

Increased gain and SNR in PMC LO monitor circuit.

1. R20: 499 -> 50k Ohms (increases gain by 100)
2. Used Marconi to drive the LO input and readout C1:PSL-PMC_LODET
3. Fit this function and loaded it into the psl.db file. The old Kalmus way used LOGE, but I wanted to use log10, so I did. The sensor is only useful in a narrow band. Since the signal is so low at low levels, I just fit to the highest 4 points because I was too lazy to do proper weighting. Do as I say, not as I do.

Plot with data and fit attached.

** N.B.: in order to update the calibration without rebooting, I used the following command: z write C1:PSL-PMC_LOCALC.CALC "2.235*LOG(B)+12.265". This allows us to update EPICS CALC records without rebooting the IOC.

I have put in a new nominal value for the FSS fast gain:  21.5 dB. 

There is an oscillation peak in the MC error point spectra around 41.5 kHz if the FSS gain is set too high.  I used the 4395 to have a look at the MC error point, and saw that if I set the FSS fast gain any lower than about 18 dB, the peak wasn't getting any smaller than -41 dBm.  If I set the fast gain any higher than about 26 dB the peak wouldn't get any larger than about -34 dBm. 

However, if I set the gain to 19.5dB, the PC RMS drive is consistently above 2 V, which isn't so good.  If I crank the gain up to 27 dB or more, the PC RMS will stay below 0.9 V, which is great. 

As a compromise, I have decided on 21.5 dB as the new FSS fast gain.  This puts the oscillation peak at about -39.5 dBm, and the PC RMS around 1.6 V.

I changed the nominal gain by ezcawrite C1:PSL-STAT_FSS_NOM_F_GAIN 21.5.  This sets the nominal value so that the FSS screen's fast slider doesn't turn red at the new value.  And, since the MC autolocker reads this epics channel and puts that into the gain during the mcup script, the MC autolocker now uses this new gain.  For reference, it used to be set to 23.5 dB.

I am going to tweak the alignment of the beam into the AOM (before the PMC) tomorrow morning. If anybody has any objections to this, please raise a red flag.

Proposed alignment procedure:

1. Reduce PSL power to say 10% 

2.  Since the AOM is not on any sort of a mechanical stage, I will have to just play around carefully until I see a maximum power rejection into first order.

I am assuming that moving the AOM is not going to affect the input pointing because all these activities are happening before the PMC. So as long as I have the output beam from the AOM aligned to the PMC at the end, everyone should be happy.

 The fan is dying. It is changing speed erratically and stops for short time periods. It is very likely to stop rotating soon. It will halt all operations in the lab. We can not see the PMC-T power because Manasa is working on

 AOM alignment.

AOM removed from the beampath and PMC relocked. 

AOM alignment:

1. Measured the initial power after PMC as 1.30W and reduced it down to 130mW.
2. Checked the power in the AOM zero order transmission before touching it. For 0-1V modulation input, the power dropped from 125uW to 98.3uW.
3. Steered the mirror right before the AOM to increase AOM zero order transmission and then carefully moved the AOM around to obtain maximum power attenuation. I repeated this a few times and the maximum attenuation that I could obtain was 125uW to 89.2uW (~30% attenuation).
Although this is not the right way to align the AOM, we do not have much options with the current setup as there is not enough separation between the zero order and first order beams and the AOM is on a fixed rigid mount.
4. I tried to dump the first order beam from the AOM and it wasn't satisfactory as well. There is barely any separation between the zero order and first order beams.

PMC relocking:

1. SInce the alignment to the PMC was disturbed by moving the AOM and the steering mirror in front of it, the PMC alignment was lost.
2. I could not relock the PMC at low power or high power. Rana had to come to rescue and fixed the alignment so that we could see flashes of PMC on the trans camera (This was done by aligning refl beam to the PMC REFL PD while giving a triangular ramp to the PMC PZT voltage).
Also I should not have tried to lock the PMC at high power as I could have been steering the beam at high power to the edges of the PMC mirrors that way and burning stuff easily.
3. Before fine tuning the alignment, I decided to remove the AOM from the beam path as there needs some work done on it to make it useful.
4. I removed the AOM from the beam path and relocked the PMC. 
5. PMC is relocked with 0.79 counts in TRANS and I measured the power after PMC 1.30W

Attachment: picture showing AOM removed from the beampath.

[Koji, Manasa]

The air flow from the dying fan was kinda weak and we decided to give a help with an external fan.

Koji brought a fan taken from a junk found at EE shop in W.Bridge.
The fan has been tied to the cage of the existing fan using cable ties to provide air circulation.
So even if the existing one dies anytime, we still don't super-heat anything.
The power supply for the fan rests next to the controller. 

The air from the fan ventilation was hot, and now with the additional fan this hot air is actually sucked
out with stronger flow. So this is relieving for now.

     PMC transmission as an indicator of laser controller with extra fan solution: 8 and 1day plot

Hello Steve, 

I’ve received some fan pictures from our manufacturing center. Your system will have one of the two fans pictured. Please contact manufacture company   for more information.

http://www.sunon.com/index.php

Best Regards,

Agustin (TJ) Tijerina

Commercial Product Support Center

Coherent, Inc.

5100 Patrick Henry Dr., Santa Clara, Ca. 95054

Product Support: (800) 367-7890

product.support@coherent.com

www.coherent.com

 Finally we got it!

The fans are ordered.

FSS Slow set point to be zero

op340m:FSS>cat FSSSlowServo
#!/usr/bin/perl -w

# PID Servo for PSL-FSS (Slow)
# Tobin Fricke 2007-01-09

use strict;
#use Scalar::Util qw(looks_like_number);

sub looks_like_number {
    return ($_[0] =~ /^-?\d+\.?\d*$/);  #FIXME
}

use EpicsTools;

# Parameters
my $process  = 'C1:PSL-FSS_FAST';
my $actuator = 'C1:PSL-FSS_SLOWDC';
#my $setpoint = 5.5;
my $setpoint = 0;
my $blinkystatus = 0;
 

op340m:scripts>/opt/rtcds/caltech/c1/scripts/PSL/FSS/FSSSlowServo > /cvs/cds/caltech/logs/scripts/FSSslow.cronlog &

The PSL HEPA was off. It was turned on and it is running at 30VAC now.

 Our janitor turned off the laser accidentally. 

 The PMC wasn't locking very happily after this. I tweaked the pointing onto the PMC REFL diode, to make sure it was centered, and touched the alignment into the PMC. I also reset the FSS Slow output to zero. It took a little while for the laser to settle in, for some reason, but the transmission is up at 0.80 now. 

Tweaked MC2 pointing to get the MC transmission high enough to let WFS kick in, which nicely got the rest of the MC alignment done. After that, I offloaded the WFS into the MC suspensions. 

Lastly, I ran the command that Rana posted in ELOG 10391, to set the FSS input offset (From -0.18 to -0.06)

 Didn't you take this opportunity to replace the cooling fan of the innolight controller?

 PMC is fine.  There are sliders in the Phase Shifter screen (accessible from the PMC screen) that also needed touching. 

PSL shutter is still closed until Steve is happy with the vacuum system - I guess we don't want to let high power in, in case we come all the way up to atmosphere and particulates somehow get in and get fried on the mirrors. 

 The Variac burned out and it was replaced. Each unit was checked out individually. HEPA -north is still noisy at full speed.

I aligned the beam into the PMC, mostly in yaw.  Don't know why it drifted, but it was annoying me, so I fixed it.

I am not sure if people have been noticing it lately; but the slow actuator on the PSL FSS has been railing up quite often these days. I found it at >0.8 and as high as 1.5 on certain occasions before resetting it to nominal zero.

It could be because the PMC alignment needs to be tweaked. The night crew should consider doing this before starting to lock.

 Found that the PMC gain has been set to 5.3 dB instead of 10 dB since 9 AM this morning, with no elog entry.

I also re-aligned the beam into the PMC to minimize the reflection. It was almost all in pitch.

I wonder if the variable bump around 100 kHz can be something about the NPRO and if the bump we see is the closed loop response due to the Noise Eater.

This plot (from the Mephisto manual) shows the effect of the NE on the RIN, but not the frequency noise. I assume its similar since the laser frequency noise above 10 kHz probably just comes from the pump diode noise.

I went out to the PSL and turned off the NE at ~4:53 PM local time today to see what happened. Although the overall PCDRIVE signal looks more ratty, there is no difference in the spectra of ON/OFF when the PCDRIVE is low. When its noisy, I see a tiny peak around 1 MHz with NE OFF. Turned it back on after a few hours.