When Sanjit and I were looking at the adaptive filtering system on Monday and Friday, we noticed that turning on the Accelerometers (which had been used in the past) seemed to do good things, but that turning on the seismometers (which I just put into the system last week) made the OAF output integrate up.  Rana pointed out that this is an indication of a missing high pass filter.  And indeed, when I put the seismometers in, I neglected to copy the high pass filter at low frequencies, and the low pass at 64Hz from the accelerometer path to the seismometer path.  The accelerometers had a HP at 1Hz, which is okay since they don't really do useful things down to the mHz level.  I gave all of the seismometers HP at 1mHz.  These are now in the filter banks in the ASS_TOP_PEM screen.  The accelerometers are on channels 15, 16, 17, 18, 19, 20 and the seismometers are on channels 2, 3, 4, 10, 11, 12, 24.

I now need to modify the upass script to turn these filters on before doing adaptive filtering.

Valera and I put the 2 Guralps and the Ranger onto the big granite slab and then put the new big yellow foam box on top of it.

There is a problem with the setup. I believe that the lead balls under the slab are not sitting right. We need to cut out the tile so the thing sits directly on some steel inserts.

You can see from the dataviewer trend that the horizontal directions got a lot noisier as soon as we put the things on the slab.

 You'll have to ask Steve how deep he cut, but the tile is cut around the lead balls, so they are not sitting on the linoleum.  They might just be sitting on the concrete slab, or whatever Steve found underneath the tile, instead of fancy steel inserts, but at least they're not on the tile.  I don't know why things got noisier though...

Global damping screens are in progress for the new global damping infrastructure Jamie discussed in log #8159. The main overview screen is /opt/rtcds/caltech/c1/medm/c1sus/master/C1SUS_GLOBAL.adl. The overview screen links to a few sub-screens in the same directory called C1SUS_GLOBAL_DAMPFILTERS.adl, C1SUS_GLOBAL_GLOBALTOLOCAL.adl, and C1SUS_GLOBAL_LOCALTOGLOBAL.adl.

This global damping is in intended to damp the 4 test masses along global interferometer degrees of freedom that are orthogonal to the cavity signals. Ideally the result will be that OSEM sensor noise from the damping loops is invisible to the cavity signals. Mismatches in the suspensions' dynamics and gains will cause some noise to leak through anyway, but we should be able to tune some of this out by carefully scaling the drives to each suspension.

I started to modify another green PD set.

It so far has the transimpedance of 240 Ohm on CLC409 for the RF output.

It shows the BB output upto ~100MHz.
The measurement shows the transimpedenca of ~90Ohm which is ~25% smaller than the expected gain of 120Ohm.
It is calibrated based on the transimpedances of Newfocus 1611 (10kOhm and 700Ohm for AF and RF).

The next step is to change the transimpedance resister to 2k and replace the PD to S3399 Si PD, which has the diameter of 3mm.
Then, the noise level will be measured. (and replace the RF opamp if necessary)

 Ooh. Can you explain the purpose of the resistors which are connected to the (+) inputs? It looks like some real electronics ninjitsu.

51 Ohm for CLC409

The datasheet of CLC409 uses 25Ohm there. This is to cancel the input bias current of the two inputs of the opamp.

The source impedance (series) of SGD444 is 50Ohm. So I used 50Ohm for the + input shunting.

However, I could probably use anything between 0-50Ohm as the datasheet itself tells that the bias currents are
not related between the two inputs. In addition, I am not sure how much the real series resistance of the PD is.

1kOhm for OP27

This resister is to ensure the (+) input to have a high impedance at high frequencies.

As far as OP27 is behaving as an ideal opamp, the (+) input has a high impedance.
Also if the inductor behaves as the ideal inductor, no photocurrent comes to the AF path.

However, if both of the op27 and the inductor show similar impedances to the RF transimpedance of 240Ohm,
the AF path absorbs some photocurrent and affects the RF transimpedance of the RF output.

We know that the inductor has a self resonance where the shunt capacitance take over the impedance of the coil.
Above that frequency, the inductor is no longer the inductor. The self resonant freq of this inductor is ~300MHz. It is OK, but not
too far from the freq of interest if we like to see clear cut off at around f>100MHz.
Also OP27 is an AF amplifier and I had no confidence about the input impedance of the OP27 at 100~300MHz.

If I put 1k in the (+) input of the OP27, I can ensure the entire AF path has the impedance of ~1k (at least 500Ohm even when L and OP27 are shorted).
I think the chip resister easily works as a resister up to 1GHz.

Correction:

The (-) input has been decoupled by the capacitor. So the series resistance of the PD is not the matter.
In this sense, we should use 0Ohm for the (+) input shunting.

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

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

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

I changed the heater circuit described in this elog to a current sink. The new and old circuits are shown in the attachment. The heater is  and is currently 24Ω; the sense resistor  is currently 6Ω. The op-amp is still an OP27 and the MOSFET is still an IRF630.

The current through the old circuit was saturating because the gate voltage on the MOSFET was saturating at the op-amp supply rails. This is because the source voltage is relatively high: .

In the new circuit the source voltage is lower and the op-amp can thus drive a large enough to draw more current (until the power supply saturates at 25V/30Ω = 0.8A in this case). The source and DAC voltages are equal in this case and so the current is . Since this is the same current through the heater, the drain voltage is . I observed this behavior in this circuit until the power supply saturated at 0.8A. Note that when this happens and the gate voltage saturates at the supply rails in an attempt to supply the necessary current.

In order to more-securely mount the TT supsion to the horizontal sliding base, I have made a sub-mounting plate (upon Koji's suggestion) to go in between the horizontal sliding base and the TT suspension base. I made many mistakes in this once-pristine aluminum board. I learned that using a ruler is not good enough for determining where to make holes. Upon Koji's suggestion, I have completed the mounting plate by first making a full-scale diagram on Solid Works, printing it out, and then using the diagram to determine where to make my punch holes. Thank you also to Manuel for helping me drill and to Suresh for teaching me how to use the taps!

I have been able to successfully mount the plate to the horizontal sliding platform. The TT suspension base is mounted to the front of the mounting plate (there are counter-sink screws at the front connecting the platform to the slider so that the screw heads do not obstruct the TT base). I have been able to successfully mount the TT suspension base to the mounting plate. I have also reattached the TT suspension frame to its original base (the one that I modified so that the TT could be mounted to a 1 inch pitch surface). Currently, the TT suspension is mounted to the optical table I have been working on (next to the MC-2 chamber). I am working on balancing the mirror. I am going to balance the mirror using a 670nm LED laser.

Below is a picture of the laser and the laser block I am using. After I took this photo, I have mounted the laser and the block to the optical table next to the MC-2 chamber.

I have already leveled the laser and I will plan to work on balancing the mirror tomorrow morning (my hands were shaking a lot this afternoon/evening, so I think it would be best to wait until the morning when I will be more careful). I am now going to work on the second half of my photosensor circuit box and second sensor head.

Please do not touch the 670nm laser on the optical table next to the MC-2 chamber! It has been leveled. Please also be careful around the optical table, since the TT suspension is mounted to the table!

The new hysteresis model uses a triangle wave with offset zero points as the position function and a sinusoidal force function, creating a loop similar to this. Model is at /users/mjenson/matlab/ferro_hyst.mdl.

We picked a few parameters from 40m summary page and plotted them to see the effect of new settings. On April 4th, old settings were present. On April 28th (16091), new input matrices and F2A filters were uploaded but suspension gains remained the same. On May 5th (16120), we uploaded new (higher) suspension gains. We chose Sundays on UTC so that it lies on weekends for us. Most probably nobody entered 40m and it was calmer in the institute as well.

• On MC_F spectrum, we see that that noise decreased in 0.3-0.7 Hz but there is more noise from 1-1.5 Hz.
• On MC_TRANS_QPD, we see that both TRANS PIT and YAW signals were almost twice as noisy.
• On MC_REFL_DC too, we see that the noise during the locked state seems to be higher in the new configuration.

We can download data and plot comparisons ourselves and maybe calculate the spectrums of MC_TRANS_PIT/YAW and MC_REFL_DC when IMC was locked. But we want to know if anyone has better ways of characterizing the settings that we should know of before we get into this large data handling which might be time-consuming. From this preliminary 40m summary page plots, maybe it is already clear that we should go back to old settings. Awaiting orders.

We have uploaded the new damping gains on all the suspensions of IMC. This completes changing all the configuration to as mentioned in 16066 and 16072. The old setting can be restored by running python3 /users/anchal/20210505_IMC_Tuned_SUS_with_Gains/restoreOldConfigIMC.py from allegra or donatella.

GPSTIME: 1304265872

[Jenne, Kiwamu, with moral support from Koji, and loads of advice from Steve and Bob]

New upgrade ITMX (ITMU03) has it's guiderod & standoff glued on, as step 1 toward hanging the ITMs.

Procedure:

1. Make sure you have everything ready.  This is long and complicated, but not really worth detail here.  Follow instructions in E970037 (SOS Assembly Spec), and get all the stuff in there.

2. Set optic in a 'ring stand', of which Bob has many, of many different sizes. They are cleaned and baked, and in the cleanroom cupboard on the bottom just behind the door. We used the one for 3" optics.  This lets you sit the optic down, and it only rests on the bevel on the outside, so no coated surface touches anything.

3. Drag wipe the first surface of the optic, using Isopropyl Alcohol.  We used the little syringes that had been cleaned for the Drag Wipe Event which happened in December, and got fresh Iso out of the bottle which was opened in Dec, and put it into a baked glass jar.  The drag wipe procedure was the same as for the December event, except the optic was flat on the bench, in the ring holder.

4. Turn the optic over.

5. Drag wipe the other surface.

6. Align the optic in the guiderod gluing fixture (Step 3 in Section 3.2.1: Applying Guide Rod and Wire Standoff of E970037).

7. Set guiderod and standoff (1 guiderod on one side, 1 standoff on the other, per instructions) against the side of the optic.

8.a.  Use a microscope mounted on a 3-axis micrometer base to help align the guiderod and standoff to the correct places on the optic (Steps 4-5 of Section 3.2.1).  This will be much easier now that we've done it once, but it took a looooooong time. 

8.b.  We put the optic in 180deg from the way we should, based on the direction of the wedge angle in the upgrade table layout (wedge angle stuff used a "Call a Friend" lifeline.  We talked to Koji.) The instructions say to put the guiderod and standoff "above" the scribe lines in the picture on Page 5 of E970037 - the picture has the arms of the fixture crossing over the scribe lines.  However, to make the optic hang correctly, we needed to put the guiderod and standoff below the scribe lines.  This will be true as long as the arrow scribe line (which marks the skinniest part of the optic, and points to the HR side) is closest to you when the optic is in the fixture, the fixture is laying on the table (not standing up on end) with the micrometer parts to your right.  We should put the other ITM into the fixture the other way, so that the arrow is on the far side, and then we'll glue the guiderod and standoff "above" the scribe lines.  Mostly this will be helpful so that we can glue in exactly the places the instructions want us to.

8.c.  The biggest help was getting a flashlight to help illuminate the scribe lines in the optic while trying to site them in the microscope.  If you don't do this, you're pretty much destined to failure, since the lights in the cleanroom aren't all that bright. 

8.d.  The micrometer mount we were able to find for the microscope has a max travel of 0.5", but the optic is ~1" thick.  To find the center of the optic for Step 5 in the guiderod and standoff alignment we had to measure smaller steps, such as bevel-to-end-of-scribe-line, and length-of-scribe-line then end-of-scribe-line-to-other-bevel.  Thankfully once we found the total thickness and calculated the center, we were able to measure once bevel-to-center. 

9. Apply glue to the guiderod and standoff.  We made sure to put this on the "down" side, which once the optic is hung, will be the top of the little rods.  This matches the instructions as to which side of the rods to apply the glue on.  The instructions do want the glue in the center of the rod though, but since we put the optic in the fixture the wrong way, we couldn't reach the center, so we glued the ends of the rods.  We will probably apply another tiny dab of glue on the center of the rod once it's out of the fixture, perhaps while the magnet assemblies are being glued.

10.  We didn't know if the airbake oven which Bob showed us to speed up the curing of our practice epoxy last night was clean enough for the ITM (he was gone by the time we got to that part), so for safety, we're leaving the optic on the flow bench with a foil tent (the foil is secured so there's no way it can blow and touch the optic).  This means that we'll need the full curing time of the epoxy, not half the time.  Maybe tomorrow he'll let us know that the oven is in fact okay, and we can warm it up for the morning.

 We have made a new plan for the ITMY and SRM oplev optical path which uses as few optics as possible. This should help to reduce coupling from vibrations of optics in the oplev path back into the GW channel. To get enough room for the turning mirror into the SRM it might be necessary to move the POY optics a bit nearer to the tank. 

I've got most of the new Mode Matching Telescope figured out.  The scripts and an example result are at: MMT09 wiki  (Rather, the scripts are in the svn: MMT svn)

Issues still to be resolved: 

* We're getting pretty iffy 'angles' between tilt and translation when using the mode matching mirrors for steering.

* I haven't taken into account the astigmatism which occurs when you tilt the mode matching mirrors. 

The nifty thing about these scripts is that they take a look at the mode matching overlap:  For each possible mode matching solution it adds noise to all of the distances and radii of curvature during ~10,000 iterations and plots a histogram of the overlap so that we can see which solutions have a better chance of giving us the optimal overlap, even if we place the optics in slightly the wrong place.

I'd like to update the overlap part of the script with the astigmatism business:  do we lose goodness of overlap if we tilt the mirrors by a bit?  I think this will require redoing the overlap part with the X and Y directions separate.  Koji has done this in the past.  My current code assumes that the beam is always symmetric in X and Y. 

[Koji Jamie]

The new c1lsc code has been installed. The LSC screens have also been updated (except for ASS screen).

The major changes are:

1. Naming of the RFPD channels. Now the PD signals were named like:

REFL11_I_IN1, REFL11_I_IN2, REFL11_I_OUT ....

instead of REFL11I_blah

2. NREFL11, etc has been removed. We now have the official error signals
named like

REFL11_I_ERR

We can't use the name "REFL11_I" for the error signal as this name is
occupied by the name of the filter module.

In order to try out the new locking scheme tonight, I have modified the LSC model.  Screens have not yet been made.

It's a bit of a special case, so you must use the appropriate filter banks:

CARM filter bank should be used for ALS lock.  MC filter bank should be used for the REFL1f signal. 

The output of the MC filter bank is fed to a new filter bank (C1:LSC-MC_CTRL_FF).  The output of this new filter bank is summed with the error point of the CARM filter bank (after the CARM triggered switch).

The MC triggering situation is now a little more sophisticated than it was.  The old trigger is still there (which will be used for something like indicating when the REFL DC has dipped).  That trigger is now AND-ed with a new zero crossing trigger, to make the final trigger decision.  For the zero crossing triggering, there is a small matrix (C1:LSC-ZERO_CROSS_MTRX) to choose what REFL 1f signal you'd like to use (in order, REFL11I, REFL11Q, REFL55I, REFL55Q).  The absolute value of this is compared to a threshold, which is set with the epics value C1:LSC-ZERO_CROSS_THRESH.  So, if the absolute value of your chosen RF signal is lower than the threshold, this outputs a 1, which is AND-ed by the usual schmidt trigger. 

At this moment, the input and output switches of the new filter bank are off, and the gain is set to zero.  Also, the zero crossing selection matrix is all zeros, and the threshold is set to 1e9, so it is always triggered, which means that effectively MC filter bank just has it's usual, old triggering situation.

With the Y Arm locked, we checked that we indeed can get loop decoupling using this technique.

The guess filter that we plugged in is a complex pole pair at 1 Hz. We guessed that the DC gain should be ~4.5 nm count. We then converted this number into Hz and then into deg(?) using some of Jenne's secret numbers. Then after measuring, we had to increase this number by 14.3 dB to an overall filter module gain of +9.3.

The RED trace is the usual 'open loop gain' measurement we make, but this time just on the LSC-MC path (which is the POY11_I -> ETMY path).

The BLUE trace is the TF between the ALS-Y phase tracker output and the FF cancellation signal. We want this to be equal ideally.

The GREEN trace is after the summing point of the ALS and the FF. So this would go to zero when the cancellation is perfect.

So, not bad for a first try. Looks like its good at DC and worse near the red loop UGF. It doesn't change much if I turn off the ALS loop (which I was running with ~10-15x lower than nominal gain just to keep it out of the picture). We need Jenne to think about the loop algebra a little more and give us our next filter shape iteration and then we should be good.

I have modified the LSC trigger matrix screen, as well as the LSC overview screen, to reflect the modifications to the model from yesterday. 

Also, I decided that we probably won't ever want to trigger the zero crossing on the Q phase signals of REFL.  Instead, we may want to try it out with the single arms, so the zero crossing selection matrix is now REFL11I, REFL55I, POX11I, POY11I, in that order. 

I have calculated the response of this new 2.5 loop system.

The first attachment is my block diagram of the system.  In the bottom left corner are the one-hop responses from each green-colored point to the next.  I use the same matrix formalism that we use for Optickle, which Rana described in the loop-ology context in http://nodus.ligo.caltech.edu:8080/40m/10899. 

In the bottom right corner is the closed loop response of the whole system.

Also attached is a zipped version of the mathematica notebook used to do the calculation.

EDIT, JCD, 17Feb2015:  Updated loop diagram and calculation:  http://131.215.115.52:8080/40m/11043

The goals are:

- When the REFL path is dead (e.g. S_REFL = 0), the system goes back to the ordinary ALS loop. => True (Good)

- When the REFL path is working, the system becomes insensityve to the ALS loop
(i.e. The ALS loop is inactivated without turning off the loop.) => True when (...) = 0

Are they correct?

Then I just repeat the same question as yesterday:

S is a constant, and Ps are cavity poles. So,  approximately to say, (...) = 0 is realized by making D = 1/G_REFL.
In fact, if we tap the D-path before the G_REFL, we remove this G_REFL from (...). (=simpler)
But then, this means that the method is rather cancellation between the error signals than
cancellation between the actuation. Is this intuitively reasonable? Or my goal above is wrong?

EDIT, JCD, 17Feb2015:  Updated loop diagram and calculation: http://131.215.115.52:8080/40m/11043

Okay, Koji and I talked (after he talked to Rana), and I re-looked at the original cartoon from when Rana and I were thinking about this the other day.

The original idea was to be able to actuate on the MC frequency (using REFL as the sensor), without affecting the ALS loop.  Since actuating on the MC will move the PSL frequency around, we need to tell the ALS error signal how much the PSL moved in order to subtract away this effect. (In reality, it doesn't matter if we're actuating on the MC or the ETMs, but it's easier for me to think about this way around).  This means that we want to be able to actuate from point 10 in the diagram, and not feel anything at point 4 in the diagram (diagram from http://131.215.115.52:8080/40m/11011)

This is the same as saying that we wanted the green trace in http://131.215.115.52:8080/40m/11009 to be zero.

So.  What is the total TF from 10 to 4? 

. 

So, to set this equal to zero (ALS is immune to any REFL loop actuation), we need .

Next up, we want to see what this means for the closed loop gain of the whole system.  For simplicity, let's let , where * can be either REFL or ALS. 

Recall that the closed loop gain of the system (from point 1 to point 2)  is

, so if we let   and simplify, we get

This seems a little scary, in that maybe we have to be careful about keeping the system stable.  Hmmmm.  Note to self:  more brain energy here.

Also, this means that I cannot explain why the filter wasn't working last night, with the guess of a complex pole pair at 1Hz for the MC actuator.  The  ALS plant has a cavity pole at ~80kHz, so for our purposes is totally flat.  The only other thing that comes to mind is the delays that exist because the ALS signals have to hop from computer to computer.  But, as Rana points out, this isn't really all that much phase delay below 100Hz where we want the cancellation to be awesome. 

I propose that we just measure and vectfit the transfer function that we need, since that seems less time consuming than iteratively tweaking and checking. 

Also, I just now looked at the wiki, and the MC2 suspension resonance for pos is at 0.97Hz, although I don't suspect that that will have changed anything significantly above a few Hz.  Maybe it makes the cancellation right near 1Hz a little worse, but not well above the resonance.

Not so fast!

In the drawing, the FF path should actually be summed in after the Phase Tracker (i.e. after S_ALS). This means that the slow response of the phase tracker needs to be taken into account in the FF cancellation filter. i.e. D = -A_REFL * P_ALS * S_ALS. Since the Phase Tracker is a 1/f loop with a 1 kHz UGF, at 100 Hz, we can only get a cancellation factor of ~10.

So, tonight we added a 666:55 boost filter into the phase tracker filter bank. I think this might even make the ALS locking loops less laggy. The boost is made to give us better tracking below ~200 Hz where we want better phase performance in the ALS and more cancellation of the ALS-Fool. If it seems to work out well we can keep it. If it makes ALS more buggy, we can just shut it off.

Its time to take this loop cartoon into OmniGraffle.

[Rana, Jenne]

While meditating over what to do about the fact that we can't seem to hold PRMI lock while reducing the CARM offset, we have started to nucleate a different idea for locking. 

We aren't sure if perhaps there is some obvious flaw (other than it may be tricky to implement) that we're not thinking about, so we invite comments.  I'll make a cartoon and post it tomorrow, but the idea goes like this.....

Can we use ALS to hold both CARM and DARM by actuating on the ETMs, and sit at (nominally) zero offset for all degrees of freedom?  PRMI would need to be stably held with 3f signals throughout this process. 

1) Once we're close to zero offset, we should see some PDH signal in REFL11.  With appropriate triggering (REFLDC goes low, and REFL11I crosses zero), catch the zero crossing of REFL11I, and feed it back to MC2. We may want to use REFL11 normalized by the sum of the arm transmissions to some power (1, 0.5, or somewhere in between may maximize the linear range even more, according to Kiwamu).  The idea (very similar to the philosophy of CESAR) is that we're using ALS to start the stabilization, so that we can catch the REFL11 zero crossing. 

2) Now, the problem with doing the above is that actuating on the mode cleaner length will change the laser frequency.  But, we know how much we are actuating, so we can feed forward the control signal from the REFL11 carm loop to the ALS carm loop.  The goal is to change the laser frequency to lock it to the arms, without affecting the ALS lock.  This is the part where we assume we might be sleepy, and missing out on some obvious reason why this won't work.

3) Once we have CARM doubly locked (ALS pushing on ETMs, REFL11 pushing on MC/laser frequency), we can turn off the ALS system. Once we have the linear REFL11 error signal, we know that we have enough digital gain and bandwidth to hold CARM locked, and we should be able to eek out a slightly higher UGF since there won't be as many digital hops for the error signal to transverse. 

4) The next step is to turn on the high bandwidth common mode servo.  If ALS is still on at this point, it will get drowned out by the high gain CM servo, so it will be effectively off. 

5) Somewhere in here we need to transition DARM to AS55Q.  Probably that can happen after we've turned on the digital REFL11 path, but it can also probably wait until after the CM board is on.

The potential show-stoppers:

Are we double counting frequency cancellation or something somewhere?  Is it actually possible to change the laser frequency without affecting the ALS system?

Can we hold PRMI lock on 3f even at zero CARM offset?  Anecdotally from a few trials in the last hour or so, it seems like coming in from negative carm offset is more successful - we get to slightly higher arm powers before the PRMI loses lock.  We should check if we think this will work in principle and we're just saturating something somewhere, or if 3f can't hold us to zero carm offset no matter what.

A note on technique:  We should be able to get the transfer function between MC2 actuation and ALS frequency by either a direct measurement, or Wiener filtering.  We need this in order to get the frequency subtraction to work in the correct units.

The N2 ran out this weekend (again no reminder email, but I haven't found the time to setup the Python mailer yet). So all the valves Steve and I had opened, closed (rightly so, that's what the interlocks are supposed to do). Chub will post an elog about the new N2 valve setup in the Drill-press room, but we now have sufficient line pressure in the N2 line again. So Chub and I re-opened the valves to keep pumping on the RGA.

[Larry, Koji]

We replaced the NAT router between martian and the campus net. We have the administrative web page available for the NAT router, but it is accessible from inside (=martian) as expected.

We changed the IP address registration of nodus for the internet so that the packets to nodus is directed to the NAT router. Then the NAT router forwards the packets to actual nodus only for the allowed ports. Because of this change of the IP we had a few confusions. First of all, martian net, which relies on chiara for DNS resolution. The 40m wifi router seemed to have internal DNS cache and required to reboot to make the IP change effective.

The WAN side cable of nodus was removed.

We needed to run "sudo rndc flush" to force chiara's bind9 to refresh the cache. We also needed to restart httpd ("sudo systemctl restart httpd") on nodus to make the port 8081 work properly. 

So far, ssh (22), web services (30889), and elog (8081, 8080) were tested. We also need to test megatron NDS port forwarding and rsync for nodus, too.

Finally I turned off the firewall rules of shorewall on nodus as it is no longer necessary.

More details are found on the wiki page. https://wiki-40m.ligo.caltech.edu/FirewallSetting

I copy section 6.2 into here to share with you all what the diagnostic capabilities of the new NPRO are. Its not a lot.

We'll need to record a sample of the NPRO output beam on a regular photodiode in order to get a real power monitor. My plan is to use a regular 25-pin Dsub and run it fron the NPRO controller over to the PSL rack and hijack the old MOPA monitoring channels (3113 and 3123 ADCs).

I removed some old equipment from the rack outside the control room and stacked them next to the filing cabinets in the control room. I also mounted the new Netgear switch in the rack.

The network cables for the Martian network were moved to the new Netgear switch from the old one which had the broken fan.
The martian machines look happy so far.

Above the new switch we have the GC network switch. The two fans of it were also broken. The fans were replaced.

They are now quiet and I am quite satisfied.

IMC Calculation and Setup

I have been working in the calculation for improving the Gouy Phase separation between the WFSs. I tried different possible setup, but the three big constrains in choosing a good optical table setup are to have a Waist size that range from 1mm-2mm, the Gouy Phase  between the WFSs have to be greater than 75 degrees and there has to be a steering mirror before each WFS. I will be showing the best calculation because that calculation complies with Rana request of having both WFSs facing west and having the shortest beam path. I approximate the distances by measuring with a tape the distance where the current optics are located and by looking at the picture that I took I approximated the distance where the lenses will be placed. I'm using a la mode for calculating the gouy phase different. I attached a picture of the current optical table setup that we have. Using a la mode, I found that the current gouy phase that we have is 49.6750 degrees.

Now, for the new setup, a run a la mode and found a Gouy phase of 89.3728 degrees. I have to create a two independent beam path: one for the WFS1 and another one for WFS2. The reason for this is that a la mode place everything in one dimension so and since the WFS1 will have a divergence lens in order to increase the waist size, and since that lens should not be interacting with the waist size in the WFS2. We need two beam path for each WFS.  A la mode give us the following solution:

For the beam path of the WFS1

    label                z (m)           type             parameters        
    -----                  -----              ----             ----------        
    MC1                   0              flat mirror          none:           
    MC3                   0.1753     flat mirror          none:           
    MC2                   13.4587   curved mirror    ROC: 17.8700 (m)     
    Lens1                 29.3705   lens                  focalLength: 1.0201 (m)
    BS2                    29.9475   flat mirror          none:           
    First Mirror         30.0237   flat mirror          none:           
    Lens3                30.2000    lens                  focalLength: -0.100 (m)
    WFS1                30.4809    flat mirror         none: 

For the beam path of the WFS2

    label                   z (m)             type             parameters        
    -----                    -----                 ----             ----------        
    MC1                    0               flat mirror          none:           
    MC3                    0.1753      flat mirror          none:           
    MC2                    13.4587    curved mirror    ROC: 17.8700 (m)     
    Lens1                  29.3705    lens                   focalLength: 1.0201 (m)
    BS2                     29.9475    flat mirror          none:           
    Second Mirror    30.2650     flat mirror          none:           
    Lens2                 30.4809     lens                  focalLength: -0.075 (m)
    Third Mirror        30.5698     flat mirror          none:           
    WFS2                30.6968      flat mirror          none:  

I attached bellow how the new setup should look like in the second picture and also I include and attachment of the a la mode code.

 I used Mist to be able to see the read out that we get in the WFSs that take the Mode Cleaner Reflection and the QPD that take the transmitted from MC2. In the following, plots I'm misaligned the each mirrors: MC1, MC2 and MC3. The misalignment are in Yaw and Pitch. I'm dividing the WFSs reading by the total power reflect power, and I'm dividing the QPD for the MC2 transmission by the total transmitted power. In my Mist model, I have a laser of 1W and my EOM is modulated at 30MHz instead of 29.5MHz and the modulation depth was calculating by measuring the applied voltage using and Spectrum analyzer. I using Kiwamu measurement of modulation depth efficiency vs the applied voltage, https://dcc.ligo.org/DocDB/0010/G1000297/001/G1000297-v1.pdf,  I got a modulation depth of 0.6 mrad. I put this modulation depth and I got the following plots: The fourth and fifth attachment are for the current optical setup that we have. The sixth and seventh attachment is for the new optical setup. The eighth attachment is showing the mode cleaner cavity resonating. The last attachment contains the plots of WFS1 vs WFS2, MC2_QPD vs WFS1, MC2_QPD vs WFS3 for each mirror misaligned. The last two attachment are the MIST code for the calculation.

We have all the lenses that we need. I checked it last Friday and if everything is good we will be ready to do the new upgrade this coming Friday. For increasing the power, I check and we have different BS so we can just switch from the current setup the BS. Can you let me know if this setup look good or if I need to chance the setup? I would really love to do this upgrade before I leave.

[Kiwamu, Manuel, Jenne]

The new optics storage drawers have been populated with optics.  Each drawer is labelled.  Harsh punishments will be inflicted on anyone found disobeying the new scheme.

[steve, yuki, gautam]

The plastic tubing/housing for the fiber arrived a couple of days ago. We routed ~40m of fiber through roughly that length of the tubing this morning, using some custom implements Steve sourced. To make sure we didn't damage the fiber during this process, I'm now testing the vertex models with the plastic tubing just routed casually (= illegally) along the floor from 1X4 to 1Y3 (NOTE THAT THE WIKI PAGE DIAGRAM IS OUT OF DATE AND NEEDS TO BE UPDATED), and have plugged in the new fiber to the expansion chassis and the c1lsc front end machine. But I'm seeing a DC error (0x4000), which is indicative of some sort of timing error (Attachment #1) **. Needs more investigation...

Pictures + more procedural details + proper routing of the protected fiber along cable trays after lunch. If this doesn't help the stability problem, we are out of ideas again, so fingers crossed...

** In the past, I have been able to fix the 0x4000 error by manually rebooting fb (simply restarting the daqd processes on fb using sudo systemctl restart daqd_* doesn't seem to fix the problem). Sure enough, seems to have done the job this time as well (Attachment #2). So my initial impression is that the new fiber is functioning alright .

[steve, gautam]

This didn't go as smoothly as planned. While there were no issues with the new fiber over the ~3 hours that I left it plugged in, I didn't realize the fiber has distinct ends for the "HOST" and "TARGET" (-5 points to me I guess). So while we had plugged in the ends correctly (by accident) for the pre-lunch test, while routing the fiber on the overhead cable tray, we switched the ends (because the "HOST" end of the cable is close to the reel and we felt it would be easier to do the routing the other way. 

Anyway, we will fix this tomorrow. For now, the old fiber was re-connected, and the models are running. IMC is locked.

[steve, koji, gautam]

We took another pass at this today, and it seems to have worked - see Attachment #1. I'm leaving CDS in this configuration so that we can investigate stability. IMC could be locked. However, due to the vacuum slow machine having failed, we are going to leave the PSL shutter closed over the weekend.

[ Jenne, Clara ]

We made new channels for the microphones which came in this week, by editing C1ADCU_PEM.ini (and making an appropriate backup before we modified it) then restarting the framebuilder and the frontend computer C0DCU1.  The new channels are:

C1:PEM-AUDIO_MIC1

C1:PEM-AUDIO_MIC2

These are connected to channels 13 and 14 on the PEM ADCU board, just next to the GURALP seismometer channels.

Clara is testing the mics so the max output voltage can be limited to +-2V for the DAQ, then we'll hook them up to our new channels and listen to the IFO (and all the audio frequency noises around it).

I (think) I have finished the new PMC base riser.  The eDrawing of it (so you can view it on any computer) has been uploaded to the PMC wiki page.

I also attach it here, for comments.

Its going to need some kind of way to locate the PMC on the top. In the previous design, we had the 3 balls to decouple the body from the base. That design was flawed due to the roughness of the holes in the PMC body.

Also probably need some kind of relief on the bottom. Its possible that it would be OK like this, but I am unsure if the shop can maintain the flatness we want over the whole length and/or the flatness of any given (OLD) optical table over ~8". Its probably not a good idea to have to torque this (aluminum?) to make it conform to the optical table's shape.

 Hmmm, so, this was just meant to be a riser that goes underneath the old PMC mount, to raise it from 3" beam height to 4" beam height.  I will make another one that is a complete mount, designed for 4" beam height.  Please hold........... .......... ....... ..... ... .

[Rana, Jamie, Jenne]

SPOB DC hasn't been so good lately, so we installed a new PO DC PD on the PO table.  We used a 30% reflecting beam splitter (BS1-1064-30-1025-someotherstuff).  We didn't check with a power meter that it's a 30% BS, but it seems like that's about right.  The beamsplitter is as close as we could get to the shutter immediately in front of the regular POB/SPOB PD's, since that's where the beam gets narrow.   The new picked-off-pickoff beam goes to a Thorlabs 100A PD.  We haven't yet checked for reflected beams off the PD,  but there is a spare razor blade beam dump on the table which can be used for this purpose.  The output of this PD goes to the LSC rack via a BNC cable.  (This BNC cable was appropriated from it's previous "use" connecting a photodiode from the AP table to a bit of air just next to the LSC rack.)  Our new cable is now connected where the old SPOB DC cable used to be, at the input of a crazy Pomona Box tee.

For reference, the new levels of POB DC and SPOB DC, as measured by their BNC DC out connections is ~4mV each.  Since the beamsplitter is 70% transmissive, we used to be getting about 5.7mV on each PD.

The new photodiode puts out about 40mV, but it has an ND1.0 filter on, so if more gain is needed, we can take it off to get more volts.

I have placed the G&H mirrors and the Y1 as pictured in my proposed layout in elog 8649.  The distance between the 2" lens and the PDs has increased, so the focus point is all wrong.  I have measured the distances between optics on the table, and will pick new lenses and finish the POP layout later today or tomorrow.

For now, here are the powers measured using the Ophir power meter:

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

PRM-ITMY lock, POPDC was ~190 counts

5.29 uW after Y1 weird angle.  Can't see beam before then to measure

5.27 uW before BS50
3.5 uW before razor PD
3.00 uW before 110PD

 ------------------------

4.94 uW before y1 (after G&H's)
4.92 uW after y1
2.66 uW before razor PD
1.61 uW before 110PD

I have a lens solution for the new POP QPD, plotted below.  To get the beam size, I started with the waist at the ITM, so the out of vacuum table starts around 6 meters on this plot.  Also, "PD" is the QPD, but the position marked on the plot is the maximum distance from the 2nd lens.  In reality, I will place it a few cm after the lens.  Once I've got that laid out, I'll move the 110PD (and its lens) and the camera around so that they are in good spots relative to the beam size.

Here is a photo of the way I left the table last Thursday.  The notations in orange indicate what I need to do to make the actual table match my lens solution.