ESO LGSF Upgrade, May 2013
Upgrade of the ESO Laser Guide Star Facility
May 2013
S.A.E. Lewis, D. Bonaccini Calia, B. Buzzoni, P. Duhoux, G. Fischer, I. Guidolin, R. Holzloehner, P. Jolley, T. Pfrommer, D. Popovic, J-A. Alvarez, J. Beltran, J. Girard, F. Gonte
ESO LGSF Upgrade, May 2013
• Laser Guide Star Facility Part of Unit Telescope 4 at Paranal Observatory. Installed in 2006• Generates a single centre-launched sodium laser guide star for client AO instruments SINFONI and NACO• Upgrade project (PARLA), new laser source subsystem for LGSF• Goal to support Paranal operations, more flexible laser operation• Laser based on patented Raman fibre laser technology • Project Start / End: Nov 2011 – Feb 2013 (start of science operations)
Introduction
ESO LGSF Upgrade, May 2013
Laser Guide Star Facility
Main subsystems: • Laser source• Optical fibre injection• Photonic crystal fibre beam relay• Launch optical system behind telescope M2• Safety / aircraft avoidance
Laser Clean Room
Launch Optics
ESO LGSF Upgrade, May 2013
OpticalPower delivered to launch telescope (after relay fibre) >6 Watts (7W goal)
Sodium D2a excitation only
Broadened laser spectrum (110 MHz line spacing)
State TransitionsStartup less than 60 mins / Shutdown less than 60 mins (goal 10 mins)
Frequency Tune/Detune < 120s (goal 30s)
IDLE to ON less than 30 mins
Lifetime/Availability: 3 year lifetime
12h operation per day average
Interfaces: Optical: BRSI fibre injection system. Beam quality and stability suitable for single mode fibre coupling.
Mechanical: laser bench and electronics cabinets
Electrical/Electronic: LGSF control and safety systems, normal and UPS power
Cooling: existing stabilised coolant circuit
Environmental: Ambient temperature stability +/- 1C
RH 5-15% typical, air pressure 700-800mBar typical
Gravity invariant, clean room
System Requirements
ESO LGSF Upgrade, May 2013
Laser Guide Star FacilityLaser Guide Star Facility Control Architecture
• Workstation in Control Room• 4 x Local Control Units (VME/VX Works Systems) in Telescope Area:
• Laser LCU
• BRS Fibre Injection LCU
• Launch Telescope LCU
• Fast Jitter LCU
• Safety Interlock System
• Laser LCU TCP/IP Interface with laser local control system
ESO LGSF Upgrade, May 2013
Electronics Cabinet:Seed Laser
Pump Laser
Laser Bench:Laser head
Periscope
Phase Modulator
Beam Expander Unit
Main Optical Path
Parts of new laser system shown with blue border.
ESO LGSF Upgrade, May 2013
PARLA Bench Mechanical Layout
• Free Space Optics Mounted on Existing Optical Bench in Laser Clean Room• Shown Below with and without Covers
ESO LGSF Upgrade, May 2013
Laser Stand AloneOutput powerBeam pointing stability (transient)Beam qualityWavelength/wavelength stabilityLocal control system
Laser + Beam Relay + Fibre CouplingSoak Tests (12h runs)Software Tests (VLT SW Model)
• Control functionality• State transitions• Simulated observing cycles
Laser Tests (Europe)
50 60 70 80 90 1000
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Raman Amplifier Set Point (Percent))
Lase
r Out
put P
ower
589
nm (W
atts
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Parla Laser Output Power at 589nm versus Raman Amplifier Set Point
Laser Output Power Characteristic
ESO LGSF Upgrade, May 2013
110MHz Phase modulator broadens the laser line Overcome spectral power limitation in 27m PCF transport fibreFigures on left show calculated line spectra for peak phase shifts of: 0, 1.44 (“3 lines”), 2.63 (“4 lines”), 3.76 (“5 lines”).Solid curve shows overlap with sodium D2a line.Below the measured spectrum of the beam in the installed system.
Laser Spectral Optimisation
ESO LGSF Upgrade, May 2013
System Test Europe
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0 60 120 180 240 300 360 420 480 540 600 660 720
Opt
ical P
OW
ER (W
atts
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Time (min.)
System Test, Fibre Throughput 30th Oct 2012
Power at PCF Input
PCF Fibre Output Power
-50
-30
-10
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0 10000 20000 30000 40000 50000
Freq
uenc
y (M
Hz)
Time (Seconds)
Infra-red Frequency Error Infra-Red Frequency Error
• AIV Europe • Soak tests (12h)
ESO LGSF Upgrade, May 2013
AIV, Commissioning (Chile)
Photos courtesy Gerd Hudepohl, ESO
ESO LGSF Upgrade, May 2013
AIV Chile, Commissioning
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Tim
e (H
ours
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Log Start Date
Operating Hours Summary (Dec - Mar)
Seed ON Time
Visible ON Time
Reintegration:Base Camp Paranal (Dec)
Installation: Laser Clean Room UT4 (Jan-Feb)
Commissioning(Feb)
Science Operation
Cumulative hours during this period: Control System: 948Seed: 943Raman Amplifier: 394Visible: 371
ESO LGSF Upgrade, May 2013
Commissioning Summary
Task Description1 Sodium D2 Line Wavelength Scan2 LGS vs Pointing3 NACO and SINFONI dummy OB operation, testing the representative configurations of
the instruments
Instr. Object name Description Existing OB data
SINFONI
NGC3621 Bulgeless Galaxy with NC 083.B-0279(B)Centaurus A AGN with central black hole 280.C-5005
Haumea(TNO136108)
Solar system, trans-Neptunian object 087.C-0167(A)
NACOCentaurus A Active Galactic Nuclei 280.C-5005NGC 5139 Omega Cen. 60.A-9800(J)
Technical tests to re-commission LGSF with Telescope / Instruments SINFONI and NACO:
Science verification, repeat a number of existing and previously published OBs to verify system performance:
ESO LGSF Upgrade, May 2013
• Wavelength of laser tuned in steps through the sodium absorption line• 250MHz steps + 100MHz steps near D2a peak• LGS Brightness measured on telescope guider• Convolution of broadened laser spectrum with sodium line• Launched polarization is not controlled • Power on sky approx 6.4 Watts during test
Wavelength Scan on Sky
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-2000 -1500 -1000 -500 0 500 1000 1500 2000 2500 3000
Gui
der A
DUs
Frequency offset (MHz) from 589.1591nm
PaRLa Commissioning Wavelength Scan
250 MHz scan, EOM 28.8%100MHz scan, EOM 28.8%
ESO LGSF Upgrade, May 2013
LGS Equivalent Magnitude, Strehl Table
ALT Deg Equivalent Magnitude85.3 K-band81.2 K-band80.0 WFS eq. mv=11.9865.0 WFS eq. mv=11.8352.5 WFS eq. mv =11.9 44.7 WFS eq. mv=12.2
Return flux measured at different telescope elevations, SINFONI.
Equivalent V-Magnitude 12
NACO• NGS Strehl up to 63% at 2.17 microns, LGS Strehl measured up to 42% at 2.17 microns during commissioning (18th February)• NACO can use 14x14 WFS around 80% of time• Air Mass up to 1.8 and in twilight• Seeing enhanced / high order only from 0.75” Seeing to 0.12” FWHM K Band
SINFONI• K-Band Strehl up to around 35% measured with PARLA
ESO LGSF Upgrade, May 2013
Science Verification: NACO, SINFONI
Reconstructed SINFONI image and spectra of the core of NGC3621. Bulgeless galaxy hosting a large black hole. CO absorption lines redwardof 2.29 microns
J,H,K band images composed in asingle RGB picture, of the core ofCentaurus A, a very activeRadiogalaxy hosting a large BlackHole. NACO.
ESO LGSF Upgrade, May 2013
Laser Performance Metrics (Dec-Mar)
0.00
0.20
0.40
0.60
0.80
1.00
1.20
12.1
2.14
12.1
2.15
13.0
1.17
13.0
1.18
13.0
1.20
13.0
1.21
13.0
1.25
13.0
1.29
13.0
1.31
13.0
2.02
13.0
2.04
13.0
2.09
13.0
2.11
13.0
2.12
13.0
2.13
13.0
2.14
13.0
2.16
13.0
2.17
13.0
2.18
13.0
2.19
13.0
2.21
13.0
2.24
13.0
2.27
13.0
3.01
13.0
3.08
13.0
3.11
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3.14
13.0
3.17
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3.20
13.0
3.23
13.0
3.27
13.0
3.29
Pow
er (a
.u.)
Log File Start Date
Subsystem Optical Powers, Normalised to Means (Dec -Mar)
Visible
Raman Amplifier
Seed
• Long term follow-up • Log files• Define Performance Metrics • Trends over time – months / years• First experience with fibre laser in observatory operational environment
ESO LGSF Upgrade, May 2013
• Fibre laser commissioned in Paranal Laser Guide Star Facility• Installed in laser clean room on VLT-UT4• Goal to support Paranal operation e.g. more flexible observing with the laser• Completed AIV and commissioning in February 2013• LGS-AO science operation ongoing• First Raman fibre laser at a major observing facility.• System in operational environment gives valuable data for future systems such as AOF.
Acknowledgements: G. Hudepohl, N. Neumeyer, Y. Al Momany
Conclusion
