Weekly Report for Week Ending April 22, 2004


 Exec. Comm. Agenda
Highlights
LSC
Administration
Hanford Observatory
Livingston Observatory
MIT
Caltech
Detector
40 Meter
TNI
LASTI
Data Analysis
Adv. LIGO Development
Past Weekly Reports

The LIGO Executive Committee Agenda for Monday  April 26, 2004 will be:

(Meeting time: 10:30 am Pacific Time)

  1. Announcements
  2. LSC Issues (Saulson)
  3. Comments on Weekly Report
  4. WBS 1 LIGO I Construction (Lindquist)
      • Field Change Orders/Contingency Liens/Change Requests
  5. WBS 2 LIGO Lab Operations
      • Administration (Lindquist)
      • Sites (Raab, Zucker, Shoemaker)
      • Detector (Whitcomb, Coyne)
      • Campus Research Facilities (Weinstein (40 Meter), Libbrecht (TNI), Ottoway (LASTI))
      • Data Analysis and Computing (Lazzarini)
  6. WBS 3 and 4  Advanced R&D and LIGO II (Shoemaker)
  7. CHANGE CONTROL BOARD/TECHNICAL REVIEW BOARD SESSION AS NEEDED


Special Announcements:


Weekly Report Highlights  


LSC Issues (Saulson)


No report this week.


LIGO I Construction/LIGO Laboratory Administration (Lindquist)


Status of LSC/MOU Research Updates and Program Reports (Petrac)

No report (leave).


LIGO Weekly Site Telecon (Lindquist)

There was no site teleconference scheduled Thursday, April 22, 2004.
The list of current actions revised to reflect the status of open actions assigned through the last update (March 4, 2004) may be found at ACTION LIST.

PROPERTY MANAGEMENT (Chargois)

From: Ed Chargois <chargois_e@ligo.caltech.edu>


DOCUMENT CONTROL CENTER (Turner, Mak)

>From: Linda Turner - turner@ligo.caltech.edu>

Web pages for the DCC give simple how-to's for document numbering, easy access to the latest on-line documents, and search capabilities for the DCC database. Take a look. . .

ACCOMPLISHMENTS

> From: Cleveland Mak <mak_c@ligo.caltech.edu>

ACTIVITY

04/22/04
Packages
Faxes
In
26
35
Out
4
21

Press here to access the DOCUMENT CONTROL CENTER WEB PAGE.

COST SCHEDULE CONTROL SYSTEMS (Cunningham, Brambila, Kaufman, Salone)

From: Esther Cunningham <esther@ligo.caltech.edu>

Press here for ACCOUNTS PAYABLE HISTORY DATA.

From: "Brambila, Ruth" <Ruth.Brambila@caltech.edu>

From: Gina Salone <gsalone@ligo.caltech.edu>
From: Florence Kaufman <fkaufman@ligo.caltech.edu>
Financial reports can be found at: http://docuserv.ligo.caltech.edu/~fireport.

SUBCONTRACTS MANAGEMENT (Petrac, Jasnow)

From: irena@ligo.caltech.edu (Irena Petrac)

From: Ed Jasnow <jasnow@ligo.caltech.edu>

SUPPORT (Baldon, Lloyd, Tischler)

>Irene Baldon

>Dorothy Lloyd
>From: Ryan Tischler <rtischle@ligo.caltech.edu>

ADVANCED LIGO (Cost Schedule Control Systems) T. Frey

From: Thomas Frey <tfrey@ligo.caltech.edu>

For list of documents that are being used to develop Adv. LIGO Cost and Schedule, see http://www.ligo.caltech.edu/~tfrey/Cost_MTG_082002/


Executed overall changes to Adv LIGO baseline.  These tasks include the following:

Development of the Advanced LIGO Project Controls Guidebook continues.


Project Web Site for posting schedule and progress related data continues to be updated with the latest and greatest.


Reports (Lindquist)

LIGO Video--Tom Lucas (Lucas Productions) has been at Caltech interviewing people.  Thanks for your support.  Tom is building the "plot line" for a 20-25 minute NOVA type video on LIGO under a Grant from the NSF.  Tom will be traveling from Caltech to the Hanford site tomorrow to participate in the "star party" scheduled for April 24.


Change Control/Contingency (Lindquist)

There are no open change requests.

Human Resources (Akutagawa)

From: Cindy Akutagawa <cindy@ligo.caltech.edu>


Quality/Safety (Tyler)

>From: Bill Tyler <tyler@ligo.caltech.edu>

No report.


LIGO Hanford Observatory (LHO) and Interferometer Operations (Raab)


Summary of Commissioning Activities at LIGO Hanford Observatory (Sigg)

Site Activities

Keita Kawabe has joined the LIGO Hanford staff as a scientist.  We welcome him to the lab, and his family to Washington.

Two nights of public outreach began last Saturday.  Spring into Astronomy (Apr 17), saw about 90 visitors to the lab for a talk by Fred, stargazing with Tri-City Astronomy Club telescopes, and a video on cosmology.  National Astronomy Day (Apr 24) should attract still more visitors, and include solar astronomy and tours of LIGO.

Dewar bonks, produced in CP2's LN2 tank, remain a daily unlocking source for both Hanford interferometers.

H1 Activities

The common mode path was switched to REFL2.  In order to do this, an ND filter had to be added to avoid saturations; REFL2 can't be used with too much light.

The PSL laser swap and layout upgrade has been essentially completed. Eleven watts out of the laser lands 7.5W on the mode cleaner. Closing tasks are listed in the linked elog.

The FSS was tempermental in light of the new PSL; needed adjustment.

Shot and dark noise measurements were made of the non-resonant sideband REFL photodiode.

The 4k antisymmetric port has its own doll's house, with photo. The lucite enclosure, when purged, reduces dust-induced glitches on AS_Q by an order of magnitude. With burst analyses impacted for some 10-20h after entry, we'll want to stay out of the enclosures during science runs.

WFS1 optical path was modified.

An ND filter installed in reference cavity detector path.

H2 Activities

The hardest button to button : H2 wouldn't readily go into CM mode for several days, in part due to script problems, part due to bad alignment.  Problem solved with patient and careful checks.

DAQ

New LSC code was installed on H1.


LIGO Livingston Observatory (LLO) and Interferometer Operations (Zucker et al)



ANNOUNCEMENTS:
Gary Traylor has agreed to take on the role of Lead Operations Specialist at LLO.  Gary's expertise, insight and leadership have become legendary at LLO, and we're fortunate that he is taking on this added responsibility.

On a more somber note, after much reflection Joe Langdale has decided to pursue further studies in computer science, and will be leaving LLO in May. We're grateful for all Joe's hard work on the interferometer and vacuum system and the many intense operator shifts under his belt (not to mention the poboys), and wish him well in the future.

Public Outreach (Bonnie Wooley, Katrina Carter, Joe Giaime, and MZ)
Bonnie and Katrina hosted two enthusiastic school groups this week for site tours, hands-on science activities, and BTE painting.

Joe MC'd the annual meeting of the Livingston Parish Economic Development Council at the LLO site on Wednesday night. After his lecture, the guests retired to an outdoor dinner with live music under the LLO pavilion. Among the guests were many of the local businesspeople who played key roles in site construction, some of whom had not visited since it was a pine forest.  Many opnely expressed their gratitude and pride, and thanked LIGO for its
contribution to the community.

Mike hosted separate half-day visits by John Hunt, a senior advisor in the Physics Division at NSF, and by Richard Matzner, chair of the LIGO Program Advisory Committee (PAC). Both were interested in in-depth reports on the progress of commissioning, HEPI, and preparations for our next set of science runs; although they've each heard numerous presentations, seeing the installation and commissioning in progress was far more illuminating.

Commissioning Overview (Zucker)
HEPI continues at full steam. Piping contractors are now done with both endstations and both X and Y ends are wet and pumping.  Corner station piping has progressed to include connections to all the BSC's and HAM4, up to the final hookup (to be filled in after actuators are complete).  The installation of the first HAM actuator (on HAM4) went off very smoothly on Friday, despite the scrutiny of a film crew looking over Gary and Harry's shoulder. We now feel confident in getting to an installation pace of one actuator per day, as we had hoped. At this writing three of the four HAM4 actuators are in place.

HEPI commissioning is now in full swing at the X end. Sensors and actuators are now all active and signals coming through to the DAQ system. This afternoon the crew commanded a tentative gentle move to the hydraulic actuators. The payload responded, though not quite as planned. More work to do, but bottom line: "Eeet eees ALIVE!!!"

We installed the TCS viewport in a very short 1-day vent of the Y beamtube manifold; since we only vented the manifold, no interferometer components were exposed and the pressure has already recovered to a compatible level. The gates will be reopened Monday.

The regeneration of the third of our four cryopumps (CP1) went well, although a fault in the exterior gas handling system is preventing high-temperature bake. This should not affect post-regen performance however.

Installation of the IO WFS hardware required substantial revision to the rack wiring; this is now finished and under test (see below).

More cleanup on the X end RFI retrofit wiring continues. We are waiting on some replacements for cables which were discovered to be incompatible (although miraculously the interferometer ran just fine).

L1 Commissioning (Frolov)
Andri and I made measurements of the effect of prc offset on the full ifo lock. The effect of the prc offset on the sideband is similar to the effect we saw in the PRM lock. We also saw an increase of ~15% in the DARM optical gain.

I worked witn Rusyl, Garry, and Harry on the TCS viewport installation.  I contacted M.Smith and K.Ryan to get the drawings and instructions, and checked with Rus that we were ready for the installation. The section of the Yarm was gated off and vented by Rus, the viewports were installed this morning by Garry and Harry.

I am preparing to recommission the IO WFS servo. So far I copied the digital filters from the old MC WFS filter bank to the new one. I made a new MC WFS script to zero the RF and DC offsets script to reflect the change in the readout.

LLO Seismic retrofit (Rich Abbott)
  1. Electronics commissioning is well under way at the X end station.  So far, the signal sensing chain has been checked out and is fully functional.  The actuation chain has been checked out up to the hydraulic control valves, but the cable are not yet attached.
  2. The actuators in the X end station have been taken out of the bleed mode.  The bleed mode is used to remove trapped air from the system.  There are a few minor code issues that must be looked into, but the system is quickly nearing the system ID phase.  Within the next few days, we will be running the system ID process.
  3. The hydraulics in the Y end are running on the pressure control servo.  Final debug of that was accomplished on Wednesday.
  4. The actuators for 3 of the 4 piers on Ham 4 have been installed, and the 4th pier will probably be completed by the end of the week.
  5. The piping installation in the vertex has about 6 more weeks of work.  The work is slower than anticipated due to a reduction in the number of installers, but they are keeping up with the rest of the HEPI development schedule.  The installation task is on budget at present.
Oddvar Spjeld adds:
Safety and security (Rich Riesen)
HPLF and L1 Commissioning (Amin)

HPLF:
According to IPG's VP of Operations, IPG is still projecting an April 27th ship date for the 100 W laser.  We are expecting them to send an installation technician to initially unpack and validate the the laser.  Once this is complete, LLO has 30 days to characterize the laser and make certain it complies to our requirements.

Additionally, a group of Russian scientists from IAP Nihzy Novgorod will be arriving to begin conducting high power laser tests. Further information and high power lab progress will be noted as it becomes available.

2k Faraday Isolator:
UF now has all optical pieces and mounts constructed. We await the arrival of EOTech's Faraday rotator. It appears that we are still waiting on Northrop-Grumman to grow a crystal that meets LIGO requirements.

PSL:
I am continuing to look into the occasional RefCav lock losses. So far I have tested the 80 MHz VCO and determined that there appears to be a soft limit for sending the FSS into oscillation when an external DC offset of 0.28 VDC is applied. Also, visible and occasionally extended spikes in the FAST portion of the FSS can be seen when switching on and off this external DC signal. I am now looking into the likelyhood that the MC servo is feeding a non-zero VDC to the VCO. I have not determined the "how this would happen" yet.

The NPRO appears to be quite reliable for the past couple of weeks.  No major problems for concern, yet.

Photon Calibrators:
Continuing to be supporting cast to D. Lormand in setting up the photon calibrators. We will be testing the second laser later today for elliptical polarization.

General Computing (Roddy)
Data Analysis (Yakushin)
LDAS admin:
Data analysis:
AdL Optics Modeling and S3 Analysis (Franzen)
CDS Controls (Chethan Parameswariah)
CDS support (Ash Khan)


Detector/Technical Support (Coyne)


Seismic Upgrade Project

CDS

see also CDS meeting minutes in the commissioning archives:

CDS Software

(Rolf Bork reporting)

CDS Hardware

(Jay Heefner reporting)

PSL

(PeterKing)

OMC

(PeterKing, Bill Kells, Virginio Sannibale, Lee Cardenas)

Thermal Compensation System (TCS)

(Mike Smith)

Optics Analysis

(Mike Smith)

Optical Contamination Cavities

(Lee Cardenas, Liyuan Zhang )

OTF Lab. (W. Bridge)
The (21) pieces of the new twisted, shielded, teflon cables are under test.  We are taking ring down and beat frequency measurements as well as the RGA of the chamber every day. NO CHANGE

Absorption Test Measurement prototype in progress The sapphire substrate PINK color from Lyon, France. (314 mm Dia. X 131mm thick.) still inside the enclosure and the latest scan performed for absorption give us a result of ~25 ppm.  The substrate is in standby for further measurements.

The 80mm sapphire cube went for scan and we found extremely non-uniform surface.  We stopped the scan.

The fabrication of the rods for the enclosure is in STANDBY.  We have received (3) sapphire substrates  3" Dia x 1.0" Thick to be tested.  New modified holders is in progress for these mirrors.

We have encounter with a situation with our 30 watt laser.  We found a water leak on the power amplifier box.  We contacted Quantronix and advise us to open the box and check for the o-ring condition.  We found that the screws were very loose so we tighten them up ands check again for leak and it did hold for a day then it started leaking again.  Now we decided to open it up and check the o-ring and found none.  We decided to change for new o-ring.

Please see Dr. Zhang's report.

Scatterometer system in standby

OTF Lab at Lauritsen ROOM 38: NO CHANGE.

Cavity #3: The cavity is locked and we are taking ring down and beat frequency measurements every day as well as the RGA for the chamber.

Cavity #2: Test cavity optical set up in standby

Misc... tasks
different fixture to accommodate sapphire substrate samples are in progress.


40 Meter Interferometer (Weinstein)


Commissioning (Miyakawa, Vass, Ward, Kawamura):

PSL (Miyakawa, Vass, Ward):

Optical sensing (Kawazoe, Sakata, Ward):

Electronics (B. Abbott, Heefner, Taylor, Mageswaran):

Facility (Vass) and South Annex Bake Ovens (Taylor):


Thermal Noise Interferometer (Libbrecht)



No report.


LASTI (Ottoway)


LASTI Weekly (Allen, McInnes, Mason, Mittleman, Ottaway, Sarin, Smith)

No report.


Data Analysis and Computing (Lazzarini)


Simulation and Modeling (Bhawal)

Weekly Physics Meeting
A Week at MIT (Matt)
Seismic Noise Injection (Biplab, Virginio)
FFT for a Focussed Beam (Biplab, Hiro)
Code Development and Maintenance

e2e 2.0 release:
Alfi

LIGO Data Analysis System

Software Systems (Blackburn)

Hardware Systems (Anderson)

Caltech
(Dan Kozak)
(Stuart Anderson) MIT
(Keith Bayer)
Livingston
(Igor Yakushin)
Hanford
(Greg Mendell)
H1:LSC-AS_Q 1
H1:LSC-POB_I 1
H1:LSC-POB_Q 1
H1:LSC-SPOB_MON 1
H1:ASC-WFS1_QP 1
H1:ASC-WFS1_QY 1
H1:LSC-POY_DC 1
H1:TCS-ITMX_LASER_ENABLE 1
H1:TCS-ITMX_AOM 1
H1:TCS-ITMX_AOM_SUPPLY_TEMP 1
H1:TCS-ITMX_LASER_MON 1
H1:TCS-ITMX_AOM_RETURN_TEMP 1
H1:TCS-ITMX_CENTRAL_MASK 1
H1:TCS-ITMX_AOM_MON 1
H1:TCS-ITMX_ANNULUS_MASK 1
H1:TCS-ITMY_LASER_ENABLE 1
H1:TCS-ITMY_LASER_MON 1
H1:TCS-ITMY_AOM 1
H1:TCS-ITMY_AOM_MON 1
H1:TCS-ITMY_CENTRAL_MASK 1
H1:TCS-ITMY_ANNULUS_MASK 1
H1:LSC-POYPD_IMon 1
H1:LSC-POYPD_QMon 1
(The 1's after each name is the downsample factor; 1 mean no downsampling so all the channels will be at the same sample rate in the reduced frames as in the raw frames.)

Data Analysis Activities (Lazzarini)

Creightn:
Mendell: Shawhan: Sylvestre:
Weinstein: Yakushin: Lazzarini:

General Computing (Wallace)

MIT:
(Keith)
Livingston:
(Shannon)
Hanford:
(Christine)
CIT:
(Mike)
(Bruce Sears)
-Ilog:                                                  (4.5 days)
(Lisa) (Veronica) (Larry)


Advanced LIGO and Supporting R&D (Shoemaker)


Seismic Isolation

From: Jay Heefner <jay@ligo.caltech.edu>
From: Larry Jones <ljones@ligo.caltech.edu>

Advanced LIGO Seismic Structure

SEI Structure:

ASI is re-planning the project cost and schedule with the HAM structure fabrication removed from the task. The BSC configuration development is on plan.

LIGO has submitted comments to ASI on their process specifications for fabrication and for precision packaging of the SEI structure and pods.

The Design Review meeting for the BSC structure is scheduled for May 18, 2004. Delivery at LASTI of the BSC prototype is expected to be in November, 2004.

Actuators:

PSI has confirmed that they will be making the actuator designs self-protective from lateral shifts; that is, a shifted bobbin will contact the inner core piece before it contacts the magnets on the outside.

PSI will be using 6061-T6 for the bobbin material to minimize the effects of reheat on yield strength.

PSI is scheduled to deliver interface drawings for the actuators by April 29.

Position Sensors:

Feedthroughs were ordered from Insulator Seal. Jay has diagrammed the sensor/module setup for a chamber and has had a productive discussion with the vendor, ADE.

Seismometers:

Nothing new.

Galling/Dusting Test:

Nothing new.

Suspension

From: ctorrie <ctorrie@ligo.caltech.edu>

Russell Jones May 10th to may 19th 2004 LOCATION: Caltech
Mike Perreur-Lloyd June 1st to August 1st 2004 LOCATION: Caltech
Calum Torrie    August 2004     LOCATION: Glasgow

From: Janeen Romie <romie_j@ligo.caltech.edu>
 
AdLIGO Suspensions
Quad FEA
Still working with Dennis and Calum on Quad/SEI fea. We completed the heavy mass/high first mode model to remove enough mass to meet the mass budget (with contingency) Dennis had provided. Modal analysis was performed in Ansys and Algor to prove that the first mode is still 150 Hz. I made an IDEAS universal file in Algor and gave it to Dennis to integrate into his coupled dynamics model.

MC to LASTI in June
Coordinating with many key folks on preparing for the mode cleaner triple suspension to go to LASTI in June.

Hybrid Osems
Corona Magnetics quoted for the magnet coil winding job. They can accomplish the coil winding on a limited number of coils (the ones we need for the MC controls prototype for the LASTI installation in June) in a week, if we pay an expediting fee. I'm working with another vendor in Rosemead and hope to have a second quote by the end of this week.

Suspension Gazebo
Minitec has shipped the kit for the suspension gazebo. It is 11 feet high but can be re-configured to about 8 feet high. It is very modular so it has a number of uses, along with the primary use of mounting the quad prototype.

Suspensions Controls Prototype Testing Plan
I've incorporate all changes but I am still waiting for clarification on a few issues from Mark Barton and Caroline Cantley. I reminded them on Tuesday.

Primavera
I've completed assigning Primavera task numbers to the Quad task list such that Primavera updates and task scheduling/priorities may be done more easily. Calum has input them in the Excel version of the quad task list.  I've scheduled a meeting with the Primavera reporting personnel for Friday at 8am to make the appropriate (% completes) updates.

Catcher Development
In preparation for the four experiments to support quad catcher development, I'm redesigning a number of parts in Solidworks and will bring the prints to the machine shops this week. Calum, Helena and I also had a meeting with Jean-Marie Machowski this afternoon to discuss the covers for the optics. The meeting was very enlightening and provided us with a number of things to think about.

Input Optics

Progress Report for the Advanced LIGO Input Optics (Period: February 15 – April 1, 2004)

1. UF High Power Laser Facility at the LIGO Livingston Observatory
Cognizant Scientists: Rupal Amin and Ken Franzen

Progress at the HPLF has been in the areas of safety and equipment acquisition.  Since the primary laser and Advanced LIGO EOM prototypes have not yet arrived, no tests or experiments have been conducted.

In our last update, the HPLF had completed and obtained approval for its laser safety plan and was in conformance with LIGO laser safety protocols.  Although these protocols were adequate, a revised site stipulation regarding laser emergency shutdown procedures has been put in place.  HPLF compliance procedures involve procedures for shutting down HPLF’s lasers during an improper lab incursion.  Safety hardware and software have been procured for this purpose and await installation approval.  Additionally, the HPLF lab has satisfied local fire codes, effective at the beginning of March.  Smoke detectors and optically compliant, halon based extinguishers have been installed.

The HPLF has also acquired laser beam diagnostic components specifically for the high power laser system.  These units are a BeamScanÒ from Photon Inc. used for beam tomography and a cavity spacer to be used in precision wavefront measurements.  Both devices were made available by the California Institute of Technology.  Photon Inc. has informed the HPLF group that we should expect a BeamScanÒ to be shipped on the 23rd of April.  This will coincide with the delivery of the HPLF 100 W laser.

The HPLF eagerly awaits its new 100 W fiber laser from IPG Photonics Corp.  In an e-mail dated 31 March 2004, IPG set a shipping date between April 19 and April 23.  After it is unpacked and initially activated by their engineer, the HPLF will have 30 days to verify the performance of the laser and return it if not satisfactory.  A two year limited warrantee ensues for hardware and components that are not expected to fail.

In upcoming months, the lab plans to begin endurance testing the AdL electro-optic modulator under 100 W (single pass) and 200 W (double pass) conditions.  This experiment will also be followed by a series of RF sideband stability measurements while the EOM sustains 100 W radiation levels.  Further experiments are pending on initial results acquired from these first two basic tests. 

2. Mode Cleaner Thermal Modeling 

Cognizant Scientist: Ken Franzen

We have been testing the Melody AdLIGO mode cleaner model, written by Ray Beausoleil with input from Amber Lynn Bullington Stanford University. The Melody code aims at providing detailed steady state numerical models of interferometers taking thermal distortions into account at high input beam powers. The physical phenomena included in the present version of Melody includes aperture diffraction, mirror-field curvature mismatch, thermal lensing in substrate and coatings, thermo-elastic surface deformation, and the elasto-optical effect.

The AdLIGO mode cleaner model is still not complete since mirror-field curvature mismatch and astigmatism are not yet included for the curved mirror. However, the contribution from these effects have been estimated as small. Preliminary results from the present model indicate that the thermal distortions of the input beam leaving the mode cleaner are insignificant, i.e. much less than 1 % contamination of the carrier and sideband output beam by higher order spatial modes. Work is in progress in order to complete the model and verify these preliminary results. 

3. Laser Adaptive Optics for Advanced LIGO Mode-Matching

Cognizant Scientists: Malik Rakhmanov, Liang Zhang, and Joe Gleason

Theoretical modeling for thermal lensing has been implemented over the past month.  The model assumes that a 514 nm argon laser is used as a heating (or writing) beam to generate the desired thermal lensing effect on OG515 Schott glass.  A Nd:YAG laser is used as reading beam to evaluate the thermal lensing.  The model uses a calculated or numerically derived temperature distribution created by the writing beam to aberrate the reading beam.  Modal structure is determined by computing Gaussian mode overlap integrals. The argon and Nd:YAG beam power and mode parameters can be adjusted to determine the optimal configuration. The theoretical results confirm a variable thermal lens can be generated using different power of heating beam. 

Fig.1 shows the temperature profile on the front surface of OG515 when the power of heating beam is 4W and beam radius is 8mm.  The thermal gradient varies the optical path length (OPL) through the temperature-dependent refractive index and thermal expansion.  The OPL change results in a thermal lens through coupling to the temperature dependence of the refractive index.  Fig.2 compares the predicted to the experimentally measured dynamic focal lengths. The theoretical results are in good agreement with measurement results in focal length of thermal lens, with the focal length decreasing from approximately ¥ to 5 m with increasing heating beam power of.  Fig.3 shows the power in TEM00 mode of reading beam through the thermal lens is strongly dependent on the ratio of the size of heating beam to the size of reading beam.  Larger writing beams are better, not surprising since the reading beam will become more aberrated as it samples non-spherical optical path deformations. Fig.4 plots the TEM00 mode in the new basis (after focusing) assuming a perfect TEM00 input mode and indicates the thermal lens doesn’t introduce large-amplitude higher modes for an optimal choice of reading to writing beam ratios.    

We are now investigating the effects of heating from absorption by high power reading beam (the 125W Advanced LIGO laser).

[Figures did not come through.  If interested contact David Shoemaker or Dave Reitze (reitze@phys.ufl.edu) -pel]

4. High Power Electro-optic modulator development 

Cognizant Scientists: Wan Wu, Guido Mueller 

Electronics: For our home-made modulator, a commercial hybrid temperature controller HTC-3000 is currently used instead of the PID controller (see DCC#: LIGO-E030494-00-D) designed by Mike Marquez. The setting point resistor is adjusted to let the temperature controller work properly.  A box with ribbon cable connector on is built to hold the controller and the cable with the AMP CPC connector is built to connect the EOM to the power supply and the temperature controller.  Testing of this unit is continuing. 

New Focus RTA-based modulator: We have received our custom RTA-based New Focus modulator.  Looks like a standard New Focus EOM with a 4 mm aperture!  The modulation frequency was specified at 20 MHz for this go around.  Higher frequencies should be no problem.  

5. IO Mechanical Design 

Cognizant Engineer: Luke Williams 

Progress has been made in several areas.  First, the March LSC was attended, including talks by the systems and suspension groups that affected the layout.  Second, the layout was updated with the new 1.950m circular HAM tables.  Third, it was determined that the osems on the MC suspensions will not interfere with the laser.  Fourth, mounts and stands were designed for the Faraday Isolator.  The layout was updated to include this change as well.  Figure 5 below shows the new layout of HAM1.  Figure 2 shows a 3D model of the FI.  A variation of this will be retro-fitted into the H1 interferometer in June.

[Figures did not come through.  If interested contact David Shoemaker or Dave Reitze (reitze@phys.ufl.edu) -pel]

Core Optics

From: Helena Armandula <ahelena@ligo.caltech.edu>
 
Summary of the teleconference that took place on Wed., 21st, 2004

The teleconference took place during J-M. Mackowski's visit to Caltech. Ask Helena for associated image files.

Attendants: Sheila Rowan, Gregg Harry, Roger Route, Norna Robertson, Jean-Marie Mackowski, Bill Kells, Gari Billingsley, Riccardo DeSalvo, Helena Armandula

On the issue of adhesion of coating to sapphire, Jean-Marie mentioned once again that, cleaning sapphire before coating, is very difficult.

He examined the two sapphire substrates we sent for coating, one superpolished, the other commercially polished.  Enclosed are pictures of features observed on the superpolished substrate. The marks could be seen faintly with an intensity lamp and looking at an angle. Pictures taken under a microscope at 5x. Where the marks are seen, the coating did not stick.  These features were not observed on the commercially polished substrate. See pictures attached.

NOTE: Bill Kells made the observation that the features seen on these pictures are very similar to the ones seen on the pictures he took of the Hanford interferometer (fused silica) optics under lock.  At the time, we thought that the "smears" were cleaning marks, now????

He also measured the surface roughness on both substrates. There was not too much difference between the substrates, however, peak to valley differences were more pronounced on the commercial parts. See the attached graphs.

About film structure, effects of crystal orientation.  He was not very concerned with the materials we are testing since they are amorphous.

Coating absorption - The only limitation is the sensitivity of the measuring system with a limit of 0.4ppm for sapphire compared to the limit of 20 ppb for
fused silica.
Coating progress up-date -Jean-Marie will be shipping the coated sapphire to Peter Sneddon on April 26th. The coating is the same doped tantala that showed lower mechanical losses in fused silica substrates.

On future work LMA developed a sort of traveler to track the substrate information. See the model attached.

Mirror cover design - With Janeen and Calum we discussed a cover to protect the mirrors during handling and assembly steps.

Jean-Marie provided us with the sketches of a stainless steel shipping container. He tested parts stored in the metal containers through the years and did not see any coating changes.  Also, discussed was the mirror handler that he uses. It does not use vacuum on the coated side on the substrate like the ERGO arm. Vacuum can be a source of contamination if up-most care is not taken.

For coating purposes he favors fused silica over sapphire. Chances of coatings failing on sapphire are greater. Cleaning is problematic. Unlike sapphire, for our application (many thick layers), fused silica is a very well known material.

Ed Jasnow joined us for lunch, the contract has FINALLY been signed!!!!

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For additional information about this report, contact lindquist_p@ligo.caltech.edu