ID |
Date |
Author |
Type |
Category |
Subject |
12054
|
Wed Mar 30 11:35:24 2016 |
steve | Update | safety | BS visitor's viewport is protected with lexan |
Quote: | The four horizontal viewports of arms are protected
by 3/8" thick, 8.5" OD Lexan disk of MR10 Polycarbonate.
ITMX, ETMX, ITMY and ETMY ccd cameras are not focused now. |
BS visitor's viewport glass is now covered with Lexan MR10
Note:
this Lexan cover is in vertical orientation so becomes lose when the black anodized cover is removed.
It needs to be held in place while it's housing is taken off. |
12082
|
Tue Apr 19 10:58:53 2016 |
Steve | Update | safety | safety scans at PSL & tables |
The PSL had one 1064 nm beam to be blocked around the north east side. The end enclosures are fine.
|
12134
|
Wed May 25 11:51:40 2016 |
Steve | Update | safety | SURF 2016 safety |
Quote: |
Hello, I am Varun Kelkar. I will be working at the 40m lab as a SURF student this summer with Eric Quintero on Audio processing for real time control system signals. This week I will mostly be working on implementing basic DSP C-code offline. Currently I am trying to write a code for noise whitening.
-Varun
|
Varun has received 40m specific basic safety training today. |
12141
|
Tue May 31 16:52:58 2016 |
Steve | Update | safety | NONO |
Please do not place anything on the top of the cabinets that is not tied down. It will end up on our head in an earth quake.
|
12157
|
Wed Jun 8 10:20:14 2016 |
Steve | Update | safety | SURF 2016 safety |
Aakash Patil received 40m specific basic safety training.
Quote: |
Quote: |
Hello, I am Varun Kelkar. I will be working at the 40m lab as a SURF student this summer with Eric Quintero on Audio processing for real time control system signals. This week I will mostly be working on implementing basic DSP C-code offline. Currently I am trying to write a code for noise whitening.
-Varun
|
Varun has received 40m specific basic safety training today.
|
|
12228
|
Wed Jun 29 15:34:00 2016 |
Steve | Update | safety | SURF 2016 safety |
Praful Vasiceddy received 40m specific basic safety training.
Quote: |
Aakash Patil received 40m specific basic safety training.
Quote: |
Quote: |
Hello, I am Varun Kelkar. I will be working at the 40m lab as a SURF student this summer with Eric Quintero on Audio processing for real time control system signals. This week I will mostly be working on implementing basic DSP C-code offline. Currently I am trying to write a code for noise whitening.
-Varun
|
Varun has received 40m specific basic safety training today.
|
|
|
12311
|
Tue Jul 19 15:16:43 2016 |
Steve | Update | safety | safety training |
Our new graduate student Lydia received 40m specific safety training. |
12479
|
Fri Sep 9 11:24:15 2016 |
Steve | Update | safety | safety training |
Visiting graduate student Teng Zhang from Glasglow received 40m specific safety training yesterday. |
12565
|
Mon Oct 17 14:48:12 2016 |
Steve | Update | safety | safety training |
Ashley Fowler "high shool" student received basic 40m safety training and Lydia is her guarding angle.
|
12705
|
Thu Jan 12 10:14:49 2017 |
Steve | HowTo | safety | closing a door |
The door was not locked this morning.
Please do not use this door if you can not close it!
Last person leaving the lab should check that the latch is cut by the strike plate. |
12706
|
Thu Jan 12 13:43:02 2017 |
rana | HowTo | safety | closing a door |
This is one of those unsolved door lock acquisition problems. Its been happening for years.
Please ask facilities to increase the strength of the door tensioner so that it closes with more force. |
12707
|
Thu Jan 12 13:45:58 2017 |
Steve | HowTo | safety | closing a door |
It was requested this morning.
Quote: |
This is one of those unsolved door lock acquisition problems. Its been happening for years.
Please ask facilities to increase the strength of the door tensioner so that it closes with more force.
|
|
12868
|
Mon Mar 6 09:12:59 2017 |
Steve | Update | safety | crane inspection 2017 |
All 3 cranes inspected by professional Fred Goodbar of Konecranes and load tested with 450 lbs at max reach on Friday, March 3, 2017
|
12913
|
Tue Mar 28 16:47:40 2017 |
Steve | Update | safety | Projector bulb is out again |
Three replacement bulbs ordered
Rana can discribe how it happened.
IF A LAMP EXPLODES
If a lamp explodes, the gas and broken shards may scatter inside the projector and they may comeout of the exhaust vent.
The gas contains toxic mercury.
Open windows and doors for ventilation.
If you inhale the gas or the shardsof the broken lamp enter your eyes or mouth, consult the doctorimmediately.
Quote: |
This bulb was blown out on Feb 4, 2017 after 2 months of operation.
|
|
12921
|
Fri Mar 31 10:16:07 2017 |
Steve | Update | safety | laser safety glasses annual inspection |
Laser safety glasses cleaned in " Dawn Ultra " mild soap - water solution and measured for 1064 nm transmission at 150 mW
|
12927
|
Tue Apr 4 11:24:21 2017 |
Steve | Update | safety | Projector bulb is out again |
Shipped out for repair.
Quote: |
Three replacement bulbs ordered
Rana can discribe how it happened.
IF A LAMP EXPLODES
If a lamp explodes, the gas and broken shards may scatter inside the projector and they may comeout of the exhaust vent.
The gas contains toxic mercury.
Open windows and doors for ventilation.
If you inhale the gas or the shardsof the broken lamp enter your eyes or mouth, consult the doctorimmediately.
Quote: |
This bulb was blown out on Feb 4, 2017 after 2 months of operation.
|
|
It is back and running fine witth bulb 4-13-2017 |
12970
|
Thu May 4 08:00:54 2017 |
Steve | Update | safety | safety training |
Freshmen Rebecca Zhang as " work study undergrad " received 40m specific basic safety training yesterday. |
12994
|
Tue May 16 16:16:16 2017 |
Steve | Update | safety | safety training |
Early surfs of India Jigyasa and Kaustubh received basic 40m specific safety traning. |
13095
|
Wed Jul 5 10:23:18 2017 |
Steve | Update | safety | liquid nitrogen boil off |
The liquid nitrogen container has a pressure releif valve set to 35 PSI This valve will open periodically when contains LN2
The exiting very cold gas can cause burning so it should not hit directly your eyes or skin. Set the pointing of this valve into the corner.
Leave entry door open so nitrogen concentration can not build up.
Oxygen deficiency
Nitrogen can displace oxygen in the air, reducing the
percentage of oxygen to below safe levels. Because the brain
needs a continuous supply of oxygen to remain active, lack
of oxygen prevents the brain from functioning properly, and
it shuts down.
Being odorless, colorless, tasteless, and nonirritating,
nitrogen has no properties that can warn people of its pres-
ence. Inhalation of excessive amounts of nitrogen can cause
dizziness, nausea, vomiting, loss of consciousness, and death |
13144
|
Tue Jul 25 14:27:19 2017 |
Steve | Update | safety | safety training |
Kira Dubrovina and Naomi Wharton received 40m specific basic safety training. |
13406
|
Mon Oct 30 08:08:06 2017 |
Steve | Update | safety | safety training |
Udit Kahndelwal received 40m specific basic safety traning on Friday, Oct. 27 |
13496
|
Tue Jan 2 16:24:29 2018 |
gautam | Update | safety | Projector periodically shuts itself off |
I noticed this behaviour since ~Dec 20th, before the power failure. The bulb itself seems to work fine, but the projector turns itself off after <1 minute after being manually turned on by the power button. AFAIK, there was no changes made to the projector/Zita. Perhaps this is some kind of in-built mechanism that is signalling that the bulb is at the end of its lifetime? It has been ~4.5 months (3240 hours) since the last bulb replacement (according to the little sticker on the back which says the last bulb replacement was on 15 Aug 2017 |
13592
|
Wed Jan 31 15:46:05 2018 |
Steve | Update | safety | crane inspection |
Annual crane inspection with load tests is scheduled for Monday, Feb 5, 2018 from 8 to 11:30am
Konecranes rescheduled this appointment to: Monday, Feb 12, 2018 |
13630
|
Mon Feb 12 14:56:00 2018 |
Steve | Update | safety | crane inspection 2018 |
Our 3 cranes passed professional inspection. Fred Goodbar of Konacrane with 450 lbs load at full extension.
Certificates will be posted in 40m wiki as they arrive.
|
13843
|
Tue May 15 13:34:30 2018 |
Steve | Update | safety | surf safety training |
Pooja and Keirthana received 40m specific basic safety training. |
14031
|
Thu Jun 28 13:12:20 2018 |
Steve | Update | safety | surf safety training |
Shruti and Sandrine received 40m specific basic safety training this morning.
Quote: |
Pooja and Keirthana received 40m specific basic safety training.
|
|
14199
|
Tue Sep 18 14:02:37 2018 |
Steve | Update | safety | safety training |
Yuki Miyazaki received 40m specific basic safety training.
|
14263
|
Thu Oct 25 16:17:14 2018 |
Steve | Update | safety | safety training |
Chub Osthelder received 40m specific basic safety traning today. |
14978
|
Fri Oct 18 18:13:55 2019 |
Koji | Update | safety | Laser interlock looks OK |
I've checked the state of the laser interlock switch and everything looked normal. |
14980
|
Mon Oct 21 11:44:19 2019 |
gautam | Update | safety | Interlock reconnected to Innolight controller |
We also took this opportunity to re-connect the interlock to the Innolight controller (after it was disconnected for diagnosing the mysterious NPRO self-shutdowns). The diode pump current was dialled down to 0, the interlock wires reconnected, and then the diode current was ramped back up to the nominal 2.1 A. The fan to cool the unit remains mounted in a flaky way as we couldn't locate the frame Chub had made for a more secure mounting solution.
It seems like the pointing of the beam out of the laser head varies somewhat after the startup - I had to adjust the pointing into the PMC a couple of times by ~1 full turn of the Polaris mount screws, but the IMC has been locked (mostly) for the last ~16 hours.
Quote: |
I've checked the state of the laser interlock switch and everything looked normal.
|
|
15508
|
Thu Aug 6 22:57:20 2020 |
gautam | Update | safety | New live HV Supplies |
Be aware that there is now a KEPCO HV supply that is energized, sitting on the floor immediately adjacent to the OMC rack, east of the AP table. It is currently set to 100 V DC, and a PI PZT installed on the AP table has its 3 PZTs energized by said supply (via an OMC piezo driver). I will post pictures etc of the work from the last 10 days over the weekend. |
15544
|
Fri Aug 28 11:41:23 2020 |
gautam | Bureaucracy | safety | Crane inspection 2020 |
Mr Fred Goodbar of Konacrane was in the lab 830am-1130am today. All three cranes in the VEA were inspected, loaded with 450lb test weights, and declared in good working condition and safe to use.
- Apparently, the clackity noise heard when running the crane at the south end is a known problem - the crane was opened up and inspected sometime in the past, and no obvious cause was found. This is not expected to affect the usability of the crane.
- The travel speed of the cranes is slow - but this is apparently intentional, on the request of Steve V.
The interferometer subsystems appear normal after the inspection. |
15932
|
Wed Mar 17 15:02:06 2021 |
gautam | Update | safety | Door to outside from control room was unlocked |
I came into the lab a few mins ago and found the back door open. I closed it. Nothing obvious seems amiss.
Caltech security periodically checks if this door is locked but it's better if we do it too if we use this door for entry/exit. |
15938
|
Thu Mar 18 12:35:29 2021 |
rana | Update | safety | Door to outside from control room was unlocked |
I think this is probably due to the safety tour yesterday. I beleive Jordan showed them around the office area and C&B. Not sure why they left through the control room.
Quote: |
I came into the lab a few mins ago and found the back door open. I closed it. Nothing obvious seems amiss.
Caltech security periodically checks if this door is locked but it's better if we do it too if we use this door for entry/exit.
|
|
17659
|
Mon Jun 26 18:37:35 2023 |
Koji | Update | safety | 40m Lab Laser Safe |
40m Lab is now Laser Safe
- The PSL NPRO (Innolight) was turned off with the OFF switch and the key. The LD set current was 2.100A. The crytsal temp setpoint was 30.61degC.
The PSL AUX NPRO (LWE) was already off.
- The South End NPRO (Innolight) was found to be off (why!?). Check the LD set current to be 1.990A. The crytsal temp setpoint was 32.86degC.
ETMX Oplev HeNe was blocked in front of the head.
- The East End NPRO (LWE) did not accept the inspection showing "CABLE?" error. Turned it off and the controller DB cable was re-fastened. This allowed to check the settings. THe current adj was 0. The crytsal temp setpoint was 43.6010degC.
- Pushed the PSL table emergency laser shut-off to turn off the laser warning signs. Note that the control room laser warning sign is not lit. Is that normal? |
8285
|
Wed Mar 13 11:34:24 2013 |
Steve | Update | optical tables | table covers moved to CES |
The two acrylic optical table enclosures were moved from the carpenter shop to CES. I need to order windows. The latest quotes from Laseroptik are posted at the wiki / aux_optics page.
Things to do: order windows, draw and order window flange, install surgical tubing seals, buy and line enclosures with IR shield films. |
8342
|
Mon Mar 25 18:58:09 2013 |
Albert Yang | Update | optical tables | Optical Table Toolboxes |
For those of you who spend annoying amounts of time looking for tools, fear no more. Toolboxes for each optical table are coming!
They will probably have:
IR Viewer (a few optical tables will have IR viewers, these specific tables will be labeled in the diagram coming out later)
IR Card
Ball screw drivers (3/16 in.) 6-8 in. handle
SMA Wrench
Allen Keys
Flashlight
Various Connectors (I'll find out what's needed at some point)
Zip Ties
Small flat screwdrivers (for adjusting camera gains)
Please suggest what else may be needed in these boxes.
The boxes will be held to the side of the tables, either by magnets or screws. A diagram of where they will be placed on each optical table in order to minimize obstruction of walkways will be distributed soon. Any objections can then be noted. |
8382
|
Mon Apr 1 16:16:16 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
A heavy duty plastic box is the likeliest candidate for the optical table toolbox. It measures 5 9/16 in. x 11 5/8 in. x 4 5/8 in. and fits all the tools comfortably. ( http://www.mcmaster.com/#plastic-bin-boxes/=m4yh4m , under Heavy Duty Plastic Bin Boxes)
The list of tools has been updated to include a pen and a wire cutter as well as everything previously stated.
In addition, Steve has recommended that boxes should be secured to the walls or surfaces near the optical tables as opposed to the optical tables themselves, as to keep the tables from wobbling when tools are being exchanged.
A diagram of tentative box placements will go out soon. |
8384
|
Mon Apr 1 16:35:42 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
A heavy duty plastic box is the likeliest candidate for the optical table toolbox. It measures 5 9/16 in. x 11 5/8 in. x 4 5/8 in. and fits all the tools comfortably. ( http://www.mcmaster.com/#plastic-bin-boxes/=m4yh4m , under Heavy Duty Plastic Bin Boxes)
The list of tools has been updated to include a pen and a wire cutter as well as everything previously stated.
In addition, Steve has recommended that boxes should be secured to the walls or surfaces near the optical tables as opposed to the optical tables themselves, as to keep the tables from wobbling when tools are being exchanged.
A diagram of tentative box placements will go out soon.
|
I also took every allen key I can find so they can be sorted. They will be back in the appropriate drawer locations soon. |
8395
|
Tue Apr 2 21:11:42 2013 |
Rana | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
A heavy duty plastic box is the likeliest candidate for the optical table toolbox. It measures 5 9/16 in. x 11 5/8 in. x 4 5/8 in. and fits all the tools comfortably. ( http://www.mcmaster.com/#plastic-bin-boxes/=m4yh4m , under Heavy Duty Plastic Bin Boxes)
The list of tools has been updated to include a pen and a wire cutter as well as everything previously stated.
In addition, Steve has recommended that boxes should be secured to the walls or surfaces near the optical tables as opposed to the optical tables themselves, as to keep the tables from wobbling when tools are being exchanged.
A diagram of tentative box placements will go out soon.
|
No, the small boxes must be attached to the optical tables. They won't be heavy enough to change the table tilt.
Also, all tools must be color coded according to the optical table using the 3M Vinyl table color code:
http://www.3m.com/product/images/Vinyl-Electrical-Color-Tape-300.jpg |
8408
|
Wed Apr 3 19:01:06 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
Quote: |
A heavy duty plastic box is the likeliest candidate for the optical table toolbox. It measures 5 9/16 in. x 11 5/8 in. x 4 5/8 in. and fits all the tools comfortably. ( http://www.mcmaster.com/#plastic-bin-boxes/=m4yh4m , under Heavy Duty Plastic Bin Boxes)
The list of tools has been updated to include a pen and a wire cutter as well as everything previously stated.
In addition, Steve has recommended that boxes should be secured to the walls or surfaces near the optical tables as opposed to the optical tables themselves, as to keep the tables from wobbling when tools are being exchanged.
A diagram of tentative box placements will go out soon.
|
No, the small boxes must be attached to the optical tables. They won't be heavy enough to change the table tilt.
Also, all tools must be color coded according to the optical table using the 3M Vinyl table color code:
http://www.3m.com/product/images/Vinyl-Electrical-Color-Tape-300.jpg
|
Ok.
So the new tentative plan on the boxes is to bolt them (magnetic strips were proposed but overruled on the grounds that they're not strong enough to withstand being knocked down by accidents).
The boxes are going to be a mix of the Thorlabs Benchtop Organizer (http://www.thorlabs.com/thorProduct.cfm?partNumber=BT17) and the original box. The box will have a region covered in mesh, so tools can be placed and held there. The box will also have a spacer at the bottom, with another mesh right above it, lined up. However, this double-mesh will only cover half of the box. The other half of the box will be compartmentalized to hold things such as screws, connectors, etc. I will talk to Steve about building the boxes.
Also, using nail-polish to coat the Allen wrenches is not going to work. Nail polish does not stick easily enough. The tentative new plan is oil paint, but this is to be reviewed.
Finally, the diagram with the placement of the boxes relative to the optical tables has been put on paper, but needs to be computerized so it's easier to read. This will be done as soon as possible. |
8410
|
Wed Apr 3 23:22:20 2013 |
rana | Update | optical tables | Optical Table Toolboxes Update |
There are some tips for how to appy nail polish on YouTube from MKNails and MissJenFABULOUS. Their tips on how to prepare the site for a strong bonding strength are probably helpful for our gold/nickel coated tools. For chrome tools we may need to abrade the surface with a stone or fine sandpaper for it to take the layer better. IF the YouTube videos don't do it for you, then I suggest contacting Tom Evans at LLO to find out what kind of nail polish he uses. |
8445
|
Thu Apr 11 16:29:23 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
There are some tips for how to appy nail polish on YouTube from MKNails and MissJenFABULOUS. Their tips on how to prepare the site for a strong bonding strength are probably helpful for our gold/nickel coated tools. For chrome tools we may need to abrade the surface with a stone or fine sandpaper for it to take the layer better. IF the YouTube videos don't do it for you, then I suggest contacting Tom Evans at LLO to find out what kind of nail polish he uses.
|
This is the tentative box placement per optical table. The toolboxes are going to be color-coded by a combination of two colors (the order won't matter). The side of each toolbox will have a little panel to let you know which box corresponds to which set of colors.
On the diagram, the set of colors is simply the color of the box border and the color of the text.
If anyone has a problem with any of the colors or the box placement let me know before they are installed and become an annoyance:

Box Placements:
ETMY: Box will be attached to the underside of the table by magnets. The box will be on the north side of the optical table.
POY: Box will be attached to the side of the optical table by magnets. The box will be on the west side of the optical table.
BSPRM: Box will be attached to the side of the optical table by magnets. The box will be on the west side of the optical table.
AS: Box will be attached to the side of the optical table by magnets. The box will be on the north side of the optical table.
PSL1: Box will be inside the optical table, in the northeast corner.
PSL2: Box will be inside the optical table, in the southwest corner.
POX: Box will be attached to the side of the optical table by magnets. The box will be on the south side of the optical table.
MC2: Box will be attached to the side of the optical table by magnets. The box will be on the south side of the optical table.
ETMX: Box will be attached to the side of the optical table by magnets. The box will be on the east side of the optical table. |
8457
|
Mon Apr 15 17:44:28 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
I decided to go see what the electrical tape looks like on the other tools.
These are the tools I felt were necessary to label with tape: (the others don't seem to be terribly important in terms of not interchanging between boxes)

On another note I'm not sure why electrical tape can't be used on the Allen Wrenches too.
I also plan on ordering smaller flash lights for each table (this one is bulky and unwieldy), and filling in the gaps of the Allen Wrench sets as soon as I get the go-ahead. |
8487
|
Wed Apr 24 18:51:12 2013 |
Koji | Configuration | optical tables | PD frequency response |
The fibers should be routed beneath the electrical cables.
They should be fixed on the table for strain relieving.
The slack of the fibers should be nicely rolled and put together at the splitter side.
These are expected to be done next time when the fiber team work around the table.
We also expect to have the table photo every time the work of the day is finished. |
8502
|
Mon Apr 29 08:17:40 2013 |
Albert | Update | optical tables | Optical Table Toolboxes Update |
Quote: |
I decided to go see what the electrical tape looks like on the other tools.
These are the tools I felt were necessary to label with tape: (the others don't seem to be terribly important in terms of not interchanging between boxes)

On another note I'm not sure why electrical tape can't be used on the Allen Wrenches too.
I also plan on ordering smaller flash lights for each table (this one is bulky and unwieldy), and filling in the gaps of the Allen Wrench sets as soon as I get the go-ahead.
|
|
8505
|
Mon Apr 29 15:53:49 2013 |
Albert | Update | optical tables | Optical Table Boxes |
Quote: |
Albert, our new undergrad work force received 40m specific- basic safety training last week. Please read and sign 40m procedures booklet.
|
These are the tentative box placements. Roughly. I don't actually have the box finalized yet, but the box should be around that size.
AS1
BSPRM
ETMX
ETMY
MC2
POX
POY
How do I perspective ._. |
1020
|
Thu Oct 2 16:44:28 2008 |
steve | Summary | oplevs | optical levers |
The idea is to push the UGF to 10 Hz of the TM oplev servos with quiet HeNe laser.
We measured good intensity noise of JDS 1103P in May 2007 and converted most of the TM oplevs to it.
The ITMs still have the noisy 670nm , 1 mW, diode lasers to begin with.
In order to get 1 mW power returning to the qpds I measured the power going to TMs
and returning on qpds ...so we can select the appropriate laser power for the conversion.
40m optical lever lasers:
HeNe laser JDS 1103P, 633nm, linear polarization 500:1,
ETMX: qpd 0.12 mw (4%) reflected of 3 mW,
ETMY: qpd 0.1o (3.8%) " 2.6
BS: qpd 0.02 ( 2.5%) " 0.8
PRM: qpd 0.01 (1.3%) " 0.75
SRM: qpd 0.08 (10%) " 0.8
Coherent 670 nm Diode Lasers VLM-tm, 0.95 mW, linear polarization 100:1,
ITMX: qpd 0.1 mW (11%) reflected back from TM of 0.9 mW
ITMY: qpd 0.04 (7%) " " 0.6
It seems that JDS HeNe laser 633 nm, linear polarization 500:1, 10 mW will do the job |
1245
|
Thu Jan 22 12:08:59 2009 |
pete | Update | oplevs | oplev calibration |
Following the procedure described in Royal Reinecke's 2006 SURF report, I've calibrated the ETMY yaw oplev DOF. The idea is to sweep the mirror tilt, measuring the transmitted cavity power and the oplev error signal. The cavity power can be related to the mirror tilt in radians following D. Anderson APPLIED OPTICS, Vol. 23, No. 17, 1984.
I've made a simple matlab script which spits out the final number; it calls Royal's perl script to do the sweep. I get 420 microrad/ct for ETMY yaw. In 2006 Royal got 250 microrad/ct. Could something have changed this much, or is one of us wrong? I'll double check my procedure and do the other arm cavity oplevs, and describe it in detail when I have more confidence in it.
Kakeru and I plan to extend this to handle the PRM, SRM, and BS. One script to rule them all. |
1247
|
Thu Jan 22 23:36:50 2009 |
pete | HowTo | oplevs | arm cavity oplev calibration |
calibrated the y-arm oplevs. the procedure is contained in a matlab script. the whereabouts of this script will be revealed in a future log entry.
ITMYpit 140 microrad/ct
ITMYyaw 98 microrad/ct
ETMYpit 400 microrad/ct
ETMYyaw 440 microrad/ct (previous measurement gave 420 microrad/ct)
procedure:
1) Start with a single arm aligned and locked. Dither the mirror tilt in a DOF. Measure arm cavity power and oplev error signal. See the first attached plot.
2) Fit the plot to a gaussian and determine mu and sigma.
3) For a spherical ETM optic, the power in the cavity P(a), as a function of translational beam axis displacement a=R*sin(theta), is proportional to exp[-a^2/(2*x^2)] where x is the waist size (D. Anderson APPLIED OPTICS, Vol. 23, No. 17, 1984). The power as a function of mirror tilt in cts, P(tilt) is proportional to exp[-(tilt-mu)^2 /(2*sigma^2)]. So if R is the mirror radius then theta = arcsin(a/R) = arcsin[(1/R)*(tilt-mu)*x/sigma)].
4) Fit theta versus mirror tilt to get the calibration. See the second attached plot.
5) For a flat ITM optic, mirror tilt causes an angular displacement of the beam. The math for this case is given in Anderson. |