If I understand your elog, you are just calculating the the offset in position space that you get by having a refractive index.

Did you end up changing the mode matching so that the rayleigh range (which changes with refractive index) was confocally focused inside the crystal (e.g. Zr = 15 mm?

- As you said, I just calculated the waist position in the crystal because the speed of light changes in a medium and eventually the waist position also changes.

- Yes, I did. Once you get a beam with the right waist size, you just put your crystal at the waist position with the offset.

  In fact you don't have to think about the rayleigh range inside of the crystal because what we care is the waist size and it doesn't change.

 I thought we cared about satisfying the confocal focusing parameter, that is to say we want to set Zr = 2L_crystal. If Zr changes inside the crystal, this is the number we care about..isn't it NOT the waist size, but the rayleigh range we care about? I am not entirely sure what youre response is saying you did...

1. Calculate Zr = pi * wo^2/(lamba/n)
2. Do mode matching to get this wo in free space
3. Calculate the offset you need to move the oven by using n
4. Move hte ovens

OR

1. Calculate Zr = pi*wo^2/(lamba)
2. Do mode matching to get this in free space
3. Calculate the offset you need to move your ovens using n
4. Move your ovens

I guess the waist size would also let me know - are you using 69 um or 53 um waist size?

since the summary pages are working again, I was clicking through and noticed that there's a wandering peak in the whitened IMC spectrogram that goes from 10-30 Hz over the course of a day.

https://nodus.ligo.caltech.edu:30889/detcharsummary/day/20200909/ioo/

anyone know what this is ?

The wasp nest will be removed tomorrow from from the out side of the east arm window.

The resonant frequency of the newly arrived gravity bee detector is not known.
 

I've changed the watchdog rampdown script so it brings the SUS watchdogs to 220, instead of the 150 it previously targeted.  This is to make tripping less likely with the jackhammering going on next door.  I've also turned off all the oplev damping.

Please do not touch the watchdogs for all SUSs except for MCs,

because I am going to measure the free swinging spectra for ITMs, ETMs, BS, PRM, SRM tonight.

Today, it is good chance to summarize those data under atmospheric pressure.

thank you.

The watchdogs' issue has been solved and they are now working fine.

It was just because one of the Sorensens had been off.

For the new CDS test, I turned off the watchdogs for PRM, SRM, BS, ITMs and MCs.

I will restore these watchdogs after several hours from now.

I am leaving ITMX and ETMX freely swinging, so that later I can take the spectra and diagonalize the input matrices.

Please don't restore the watchdogs until tomorrow morning.

Tonight, swing again.

Please do not restore the watchdogs until tomorrow (Dec.9) morning.

A Caltech maintenance staff dropped by at around noon today, and told me that he had seen a small puddle of water on the other side of the door along the Y-arm that is kept locked (about 10m from the end-table, on the south side of the arm). He suspected a leak in the lab. Koji and I went down to the said door and observed that there was indeed a small puddle of water accumulated there. There isn't any obvious source of a leak on our side of the door, although the walls tiles in the area suggest that there could be a leak in one of the pipes running through the wall/under the floor. In any case, the leak doesn't seem too dramatic, and we have decided to consult Steve as to what is to be done about this once he is back on Wednesday.

The leak was found inside the wall. Fortunately the plumbers were able to access it from CES room 108

This has been leaking for sometimes. The damaged wall area is about 18 ft long and 1 ft high.

rob, koji, steve

We noticed some water (about a cup) on the floor under the NESLAB chiller today.  We put the chiller up on blocks and took off the side panel for a cursory inspection, but found no obvious leaks.  We'll keep an eye on it.

 The culprit has been found:  One of the bottles of chiller water had a tiny leak in it, and apparently the floor is sloped just right to make it look like the water had been coming from under the chiller.  All is well again in the world of chilled water.

I added ~500 cc of distilled water to the laser chiller yesterday.

We will start preparing for pumping down. Main goal for this is to demonstrate PRFPMI using ALS.
Here are to-dos before we pump down.

Feb 18 eveing
- check input beam and Y arm alignment again
- IPPOS/IPANG alignment
- check all oplevs

Feb 19 morning
- open ETMX chamber heavy door
- align BS to X end
- adjust OSEM values (added by YM)
- center beam on all AS optics
- make sure AS/REFL is clear
- take picture of flipped PR2 (added by YM)
- make sure green is not clipped by new PRM oplev mirrors  (added by YM)
- center all oplevs

Feb 19 afternoon - Feb 20 morning
- close PSL shutter
- close all heavy doors and put the access connector back
- start pumping down

Feb 20 evening
- start aligning IFO

 The chiller appears to be broken.  We currently have it on, with both the SENSOR and RS-232 unplugged.  It's running, circulating water, and the COOL led is illuminated.  But the temperature is not going down.  The exhaust out the back is not particularly warm.  We think this means the refrigeration unit has broken, or the chiller computer is not communicating with the refrigerator/heat exchanger.  Regardless, we may need a new chiller and a new laser.

steve, alberto, rob

After some futzing around with the chiller, we have come to the tentative conclusion that the refrigeration unit is not working.  Steve called facilities to try to get them to recharge the refrigerant (R-404a) tomorrow, and we're also calling around for a spare chiller somewhere in the project (without luck so far).

After a brief look this morning, I called it and declared that we were ok to close up.  The access connector is almost all buttoned up, and both ETM doors are on.

Basically nothing moved since last night, which is good.  Jenne and I were a little bit worried about how the input pointing might have been effected by our moving of the green periscope in the MC chamber.

First thing this morning I went into the BS chamber to check out the alignment situation there.  I put the targets on the PRM and BS cages.  We were basically clear through the PRM aperture, and in retro-reflection.

The BS was not quite so clear.  There is a little bit of clipping through the exit aperture on the X arm side.  However, it didn't seem to me like it was enough to warrant retouching all the input alignment again, as that would have set us back another couple of days at least.

Both arm green beams are cleaning coming out, and are nicely overlapping with the IR beams at the BS (we even have a clean ~04 mode from the Y arm).  The AS and REFL spots look good.  IPANG and IPPOS are centered and haven't moved much since last night.  We're ready to go.

The rest of the vertex doors will go on after lunch.

Today Steve and I tried to recenter the Guralps. The breakout box technique didn't work for us, so we just turned the leveling screws until we got the mass position outputs within +/-50 mV for all DoF as read out by the breakout box.

Some points:

1. GUR1 is at the ETMY (E/W arm) and GUR2 is at the X-end (South arm)
2. The SS containers are good and make a good seal.
3. We had to replace the screws on the granite slab interface plate. The heads were too big to allow the connector to snap into place.
4. The Guralps had been left way, way off level and the brass locking screws were all the way up. We locked them down after leveling today. Steve was blaming Cathy(?).
5. The GUR1_Z channel now looks good - see the summary pages for the before and after behavior. My mistake; the low frequency is still as bad as before.
6. GUR2 X/Y still look like there is no whitening or if the masses are stuck or the interface box is broken.
7. When we first powered them up, a few of the channels of both seismometers showed 100-200 Hz oscillations. This has settled down after several minutes.

The attachment shows the 6 channels after our work. You can see that GUR2_X/Y still look deadish. I tried wiggling the cables at the interface box and powering on/off, but no luck. Next, we swap cables.

Tried to bring the weather station back to life, but no luck. The unit on the wall is alive and so is the EPICS IOC (c1pem1). But there is apparently no communication between them. telnet into c1pem and the error message repeating at the prompt is:

Weather Monitor Output: NO COMM

Might be related to the flaky connector situation that Liz and I found there a couple summers ago, but I tried jiggling and reseating that one with no luck. Looks like it stopped working around 8 PM on March 24, 2014. That's the same time as a ~30s power outage, so perhaps we just need some more power cycling? Tried hitting the reset button on the VME card for c1pem1, but didn't change anything.

Let's try power cycling that crate (which has c1pem1, c0daqawg, and some GPS receiver)...nope - no luck.

Also tried power cycling the weather box which is near the BS chamber on the wall. This didn't change the error message at the c1pem1 telnet prompt.

It's been a miserable week for lock acquisition, with each night worst than the last.  The nadir was around Sunday night, when I couldn't even get a PRM to lock stably, which meant that the auto-alignment scripts could not finish successfully.  It now appears that was due to some XYCOM mis-settings. 

We've also been having problems with timing for c1susvme2.  Attached is a one-hour plot of timing data for this cpu, known as SRM.  Each spike is an instance of lateness, and a potential cause of lock loss.  This has been going on for a quite a while.

Tonight we also encountered a large peak in the frequency noise around 485 Hz.  Changing the MZ lock point (the spot in the PZT range) solved this.

Summary of the week ending Aug 8th.  Number of elog entries = 56

- VAC
 + The vent started Wednesday morning
 + Repositioning of the green periscopes and associated mirrors are done.
 + Got both of the green beams coming out from  the chambers
 + Moved the ETMX suspension tower by -8.09 inch (away from vertex)
 + Fixed the alignment of the ETMX CCD mirrors
 + Recovered the X green beam axis for the latest ETMX position

- SUS
 + oplev centered prior to the vent

- LSC
 + ETMY_TRANS_QPD didn't respond at all, needs to be fixed
 + Old MZ PD (InGaAs 2mm, @29.5MHz) has been modified for REFL33.
  The 11MHz notch circuit is at the amp side instead of the diode side. This is ready for the installation
 + REFL165 PD has been made from the old 166MHz PD.

- IOO
 + IPPOS has been sick since 19th of July, 2011
 + IPANG is clipped on a pick-up mirror on the ETMY table. QPD itself is healthy.
 + The spot positions on the MC mirrors were measured prior to the vent.
   The results are almost the same as before within a few percent difference expect for the MC2 yaw.
 + An attenuator, consisting of two HWPs and a PBS, has been installed on the PSL table for the MC low power state.
 + a 10% BS in front of the MCREFL_RFPD was replaced by a perfect reflector for the low power mode.
 + The incident power for MC was decreased to 20 mW
 + The beam axis going to MC was misalgned due to the attenutor.
    Then the beam was aligned by touching two steering mirrors on the PSL table
 + MC is able to be locked in air. The reflection DC goes from 1.4 to 0.13 V when the MC is locked.

- ABSL
 + With the mass-kicking technique, the arm lengths were measured.
   Xarm =  37.5918 m, Yarm = 37.5425 m.

- Green locking
 + Y green beam is aligned to the Y arm
 + Locking of the Y green is not robust, it needs to be revisited

- OAF
 + Wiener Filtering was applied on the data collected from the X-arm for a duration of 1500 seconds.

- Misc.
 + The hazardous waste people are moving chemicals around outside our door, and have roped off our regular front door.
 + The horizontal trolley drive of the east end crane stopped working. It will be fixed.

Weekly Project Update:

We are studying Haixing's circuit diagram for the quadrant maglev control circuit.  We have analyzed several of the sub-circuits and plotted transfer functions for these in MatLab.  To check the circuit, we will compare the calculated transfer functions with those obtained from the HP control systems analyzer.

To learn how to use the control systems analyzer, we are reading App Note 243 as well as an online manual (477 pages in the first volume).  We are beginning with a simple test circuit, and are comparing its measured frequencyresponse with calculated transfer functions.  We currently have obtained a response graph beginning at 100 Hz (which we have not yet figured out how to print), and we are planning to investigate behavior at lower frequencies.

We also have been continuing our reading on control systems after a failed attempt at magnetic levitation. 

This past week, we levitated our small cylindrical magnet (with the flag made from heat shrink).  Though the levitated magnet didn't appear very jittery to the eye, we looked at the PD current on the scope and could see oscillations that corresponded to the flag hitting the sides of the OSEM.  The oscillations were more pronounced as we gently hit/vibrated the lab bench, and by pounding on the bench Rana knocked the levitated magnet completely out of the setup.  So, we're currently working on building a new, stabler mount.  The biggest challenge here is fixing the OSEM in place, but we're experimenting with different optics pieces to see which is the most stable for our purposes.   Jenne taught us how to make through holes using the drill press so we can add slats of aluminum to adjust the height of the OSEM mount.  We also plan to fix some heavy plates to the bottom of our system to decrease its vibration frequency.

We also calculated the transfer function of our circuit, which seems to match the measured frequency response to within a small factor.  We're playing with Rana's Simulink models and are currently modeling our own system to determine what gains we would expect to use and get a better understanding of our circuit.

Once our system is successfully mounted stably, we plan to experimentally observe the effects of changing the gain and integrator by looking at time series measurements of the PD current, as well as using the spectrum analyzer to compare the frequency response of our system at different gain settings.

in the rack next to the printer.  It sounds like a fan is hitting something.

IP_POS is back. 

I reconnected the cable to an interface card : D030238-A which has been labeled as "IP POS".

The card currently resides on the third crate rack from the top at the very right side in 1Y2. Also a rear side connection was modified a little bit.

I will clean up some cables because I tried some cables to see which was which.

Hopefully I will make a simple wiring diagram such that we will never forget the connections.

Fire-smoke sensors in the vertex area #2-31, 2-30 east, 2-32 south/MC2 and 2-37 old control room area are turned off to accommodate the welding

activity of folding crane. These sensors will be reactivated at 3:30pm today.

Stay out of the 40m lab: IFO room till 6 pm today.

Kiwamu, Koji, Yutah, Rana, Jan and Steve

We removed the west access connector this afternoon.

We hypothesize that the systematic error in the loss measurement can come from the fact that the requirement on the alignment of the cavity mirrors is not stringent enough.

We repeat the loss measurement with 50 measurements. This time we change the thresholds for the error signals of the dither-align in the measureArmLoss.py file from 0.5 to 0.3.

We repeat the analysis done before:

We plot the reflected power of the two states on top of each other:

This  time it appears there was no drift. The histogram of the loss measurement:

The mean is 104ppm and the variation is 27%.

What I notice this time is that the PD readings in the aligned and misaligned states are anti-correlated. This is also true in the previous run (where there was drift) when looking in the short time scales. I plot several time series to demonstrate:

I wonder what can cause this behaviour.

SUS-ETMY_QPD is not responding. It is reading zero in dataviewer and 4,400 counts on QPD MEDM screen.......must be wrong cable connected

IP-POS is sick. Last time alive 7-19-2011

IP-ANG beam is clipping on pick-up mirror at ETMY chamber. This will have to be fixed at the vent. The qpd itself is responding to light.

Fibox FBAI-M 20bit units were connected with multimode fibre.  This pair of fiber is not protected in the cable tray.

It appears that the old PSL fast channels never made it into the new DAQ system.  We need to figure out what to do with them.

A D990155 DAQ Interface card in far right of the 1X1 PSL EuroCard ("VME") crate is supposed output various PMC/FSS/ISS fast channels, which would then connect to the 1U "lemo breakout" ADC interface chassis.  Some connections are made from the DAQ interface card to the lemo breakout, but they are not used in any RTS model, so they're not being recorded anywhere.

An old elog entry from Rana listing the various PSL DAQ channels should be used as reference, to figure out which channels are coming out, and which we should be recording.

The new ALS channels will need some of these DAQ channels, so we need to figure out which ones we're going to use, and clear out the rest.

It turned out that the DC alignment of MC2 from epics doesn't helathily work.

For example, the pitch slider does drive the yaw alignment as well.

Is this somehow related to the unknown MC2 jump happened around September 10th ?? (see the trend below)

[Yuta, Suresh, Rana and Kiwamu]

 The DC alignment problem of MC2 was fixed.

There were some loosely connected cables on the backside of a VME rack which contains the MC2 SOS driver.

We pushed those connectors to make them tightly connected.  And then the problem disappeared.

(voltage unbalance on coils)

 Before fixing it Yuta opened the satellite box and measured the voltage across the coils using a voltmeter.

At that time UL and LR showed 20 times smaller voltages than that of the other two when we moved the DC alignment slider from min. to max. on the medm screen.

This behavior is exactly consistent with the wired motion of a beam spot which we saw when we were aligning MC2. 

(diagnostic using optical lever)

 After pushing the connectors, we made an optical lever using a red laser pointer in order to check the actual motion of MC2.

We confirmed that MC2 respond correctly to the alignment slider.

Reminder: I will be on vacation next week. We would have to put the access connector in tonight if I'm pumping down Friday, tomorrow.

Photo diodes stored in the east arm cabinet E4:  ALL PDs  meet here, fast  or slow......

RFAMPD_DCMON disappered on Nov 5, 2009

Yesterday I failed to take good pictures of ETMY  resonant arm of 1064 nm with Cannon Rebel T3i in RAW 22-27Mp & JPG dual- format. UFRaw file converter worked well. The IR blocker filter seems to be too good.

Today I used Olympus SP-570UZ ( without IR blocker), in raw format of 15Mp, fl 22.4mm, 15s including 2-3s flashlight,  f/8 and auto focus  This is just too much scattered IR for the Olympus.

Overexposed raw picture' jpg is shown  at the PSL with diffraction patter of the camera.

I'll go back using  the Nikon D40 with zoom 55-200mm as this Atm2 of May 2007 : manual focus, 15s, f/4-5.6, ISO 560,  826KB

I forgot to mention about the whitening filter for the ALS digital control system.

As usual I used a whitening filter to have a good SNR against ADC noise, but this time our whitening scheme is little bit different from the usual our systems.

I used two ADC channels for one signal and put a digital summing point  and digital filters to keep good SNR over the frequency range of interest.

It's been working fine but it's still primitive, so I will study more about how to optimize this scheme.

     The diagram above shows our scheme for the signal whitening.

Basically the SNR at DC is bad when we use only a whitening filter as shown on the bottom part of the diagram because the signal is quite tiny at DC.

On the other hand if we take raw signal into ADC as 'DC path'  shown above, the SNR is better at DC but not good at intermediate frequencies (30 mHz - 1kHz).

So the idea to keep the good SNR over the frequency range of interest is to combine these 'DC path' and 'AC path' in a clever way.

     In our case, the 'DC path' signal is not as good as the 'AC path' signal above 30 mHz, so we cut off those high frequency signals by using a digital low pass filter.

In addition to it, I put a gain of 1000 in order to match the relative gain difference between 'DC path' and 'AC path'.

Then the resultant signal after the summing point keeps the good SNR with a flat transfer function up to 1 kHz. 

Precondition: c1vac1 & c1vac2 all LED warning lights green [ atm3 ], the only error message is in the gauge readings NO COMM, dataviewer will plot zero [ atm1 ], valves are operational

When our vacuum gauges read " NO COMM " than our INTERLOCKS  do  NOT communicate either.

So V1 gate valve and PSL output shutter can not be triggered to close if the the IFO pressure goes up.                        

   [ only CC1_HORNET_PRESSURE reading is working in this condition because it goes to a different compuer ] 

Atm1, ITMY and the SRM are on the same isolation stack.  So why does  the SRM move twice as much?

Atm2, We should check the ITMY  SIDE_OSEM before pump down. Anatomically correct, beautiful picture taken by Kiwamu on August 22