Transcript 04_OWL_ELT_Copenhagen_Technologies

OWL TECHNOLOGIES
Copenhagen, November 2004
Design overview
Optics
6-mirror, f/7.5,
~6,900 m² collecting area,
IAU Symposium 225 - Lausanne, July 2004 - - Slide 2
near-circular outer rim
M1
Spherical
dia. 100m, f/1.2
3048 segments
M2
Flat, dia. 25.6 m
216 segments
Corrector
4 elements,
dia. 8, 8, 3.5, 2m
FOV
6 focal stations (rotation of M6)
10 arc min. seeing-limited;
> 2 arc min.diffraction-limited (vis.)
Stability
Very low sensitivity to external
disturbances (gravity, thermal, wind)
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Optical design
Adaptive, conjugated to pupil;
First generation
Adaptive, conjugated to 8km;
Second generation
Why a spherical primary / flat secondary ?
System
Performance
Risk & cost
Larger corrected field of view than equivalent Ritchey-Chretien
Low sensitivity to M2 decenters
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Corrector  excellent baffling options
Secondary mirror an issue with aspherical primary


Small M2 (< 3-m)  very high sensitivity to disturbances
Large M2 (> 3-m)
 severe fabrication issue if convex
 added tube length if concave (Gregorian)
All wavefront control functions with 6 surfaces
Multi-conjugate AO (2 mirrors 2- and 4-m, conjugated to 0, 8 km)
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Moderately large FOV (0.5 – 2 arc min) an essential mode
Needs re-imaging; OWL provides dual conjugate with 6 surfaces only !
Maintainability: 3,000 segments, all identical & interchangeable.
Why a spherical primary / flat secondary ?
System
Performance
Risk & cost
Use of planetary polishers or large stiff figuring tools

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Lower segment edge misfigure
Stable reference, repeatability of radius of curvature
No warping harness


Structured blanks possible (SiC a serious option)
Less stringent requirements on blanks internal stresses
Segment size up to ~2.3-m possible

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Limited by cost-effective transport in standard container
No aspherization  weak size-dependence
Performance losses

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Lower throughput than a Ritchey-Chretien (option: enhanced coatings ?)
Higher emissivity (option: single surface corrector for very small field of view ?)
Why a spherical primary / flat secondary ?
System
Performance
Spherical polishing
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Simple and predictable
processes, stable and
predictable yield
Stable reference (rigid tools)
Fast process, high efficiency;
OWL polishing tool area
= 36  largest GTC tool area !
Simple test set-up
Unique matrix
 no segments matching risk
TBC: No edge cutting,
polished hexagonal
Risk & cost
Segment assembly
Segment unit
Metrology
Position sensors
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LCU
Spacers
Segment
assembly
Segment
Optical surface
Segment active
support system
Slave actuator for
lateral support
Position actuators
Segment blank
Support structure
Interface pads
Axial interface pads
Lateral interface pads
Reference targets
Whiffle-tree
Total quantity: 3048 + 216 + TBD spares
Actuators - Outline of specifications
Load cases (nominal, tension and compression)
 Glass segments:
 Lightweight SiC segments:
0 to 170 kg / actuator
0 to 40 kg / actuator
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Accuracy

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2 stages Position Actuator Concept
Coarse stage
± 0.05 mm.
Fine stage
± 5 nm - Goal ± 2 nm
Extractor
± 1 mm
Stroke
 Coarse stage
 Fine Stage
 Extractor
20 mm
0.5 mm - Goal 1mm
150 mm TBC
Closed Loop Bandwidth
 Fine stage
 Coarse stage
5Hz - Goal 10 Hz.
0.1 Hz.
Max. cost (unit cost for a production of 10,000 units)
 Glass segments:
 SiC segments
< € 3,500.< € 2,500,-
Goal < € 2,500.Goal < € 2,000.-
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Position sensors
Capacitive, inductive or optical
Mounted at segments edges
Measurement range
Differential accuracy over full range
Maximum measurement frequency
Re-calibration frequency
Maximum heat dissipassion
Maximum unit cost (20,000 units)
Cross-section through
glass / glass-ceramic segments
Variable 2 to 14 mm
  0.5 mm (TBC)
  5 nm
Goal  2 nm
20 Hz
Goal 50 Hz
 once per week
TBD (minimize)
€ 1,250.Goal € 750.Cross-section through
SiC segments
Variable 2 to 14 mm
Max. 10 mm
70 to 90 mm,
depending on segment size
Min. 70 mm
Max 10 mm Max. 10 mm
Sliding enclosure
M2 Handling tool
M1 Covers
Maintenance
facility
Azimuth tracks
Altitude bearing
Azimuth structure
& bogies
Altitude tracks
Corrector &
instrumentation
Structure ribs
(6-fold symmetry)
Altitude cradles
& bogies
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All dimensions as
multiple of segment size
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Standardization
Ease of integration
Ease of maintenance
Optimal loads transfers
Optomechanics
Fractal design - Low-cost,
Eigenfrequency (Hz)
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lightweight steel structure

14,800 tons moving mass
(60 times “lighter” than VLT)
Mass reduced to ~8,500 tons with SiC
Ample safety margins (stresses, buckling)

2.6 Hz locked rotor eigenfrequency

Low thermal inertia
(developed surface, natural internal
air circulation inside structural
elements)

Differential M1-M2 decenters
under gravity
Piston
Lateral
Tilt
3.4 mm
17.6 mm
3.4 arc secs
(rigid body
motion)
Moving mass (t)
• Innocuous lateral M1-M2 decenters
• Parallelogram-shaped
structural modules
favour lateral over
angular decenters
• Lose centring tolerances
• Corrector favourably
located (stiffness)
• Ample design
space
20305
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Reducing sensitivity by design
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Instrument racks
6 focal stations; switch
by rotating M6 about
telescope axis.
Max. instrument mass
15 tons each.
Local insulation & air
conditioning
Issue: needs rigid
connection with
corrector (TBC).
Controlled optical system
Kinematics

pointing, compensation for sky rotation
encoders, on-sky guide probe

bring optical system into linear regime
internal, tolerances ~ 1-2 mm, ~5 arc secs
re-position Corrector, M3 / M4 / M5

keep M1 and M2 phased within tolerances
Edge sensors, Phasing WFS
Segments actuators

cancel “fast” image motion
Guide probe
M6 tip-tilt (flat, exit pupil, 2.35-m)


finish off alignment / collimation
relax tolerances, control performance & prescription
Wavefront sensor(s)
Rotation & piston M5; M3 & M4 active deformations

atmospheric turbulence, residuals
Wavefront sensor(s)
M5, M6, …
Metrology:
Pre-setting
Metrology:
Correction:
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Phasing
Metrology:
Correction:
Field Stabilization
Metrology:
Correction:
Active optics
Metrology:
Correction:
Adaptive optics
Metrology:
Correction:
Controlled opto-mechanical system
I – Pre-setting
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Corrector re-centering + 2 (TBC) surfaces
within the corrector
Internal metrology
(e.g. fiber extensometer)
Typical accuracy:
10 ppm goal 1 ppm
Bandwidth
<< 1 Hz
High operational
reliability
Controlled opto-mechanical system
II – Kinematics
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Friction drives
Azimuth: 246 units
Elevation: 154 units
Bandwidth ~0.5 Hz
Fast steering mirror
M6, dia. 2.35m
Guide probes at
technical focus
accessible FOV 10’
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M6 adaptive & tip-tilt unit
Controlled opto-mechanical system
III – Active optics
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Dual conjugate active optics
Deformable M3 & M4
VLT-type mirrors
Refocus
& fine
centering
5 Wavefront Sensors
at each technical
focus (FOV 10’)
+ feedback AO
Controlled opto-mechanical system
IV – Phasing
Two segmented mirrors
Bandwidth ~5 Hz TBC
Edge sensors (capacitive,
Inductive or optical)
Reference channel
Telescope
focus
Beamsplitter
Mach-Zehnder
phasing sensor
Pinhole
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Beamsplitter
Interferogram
Interferogram
On-sky
calibration
off-axis
Mach-Zehnder calibration sensor
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Interferogram
(ideal conditions)
Complex geometry,
But fully predictable
Localized signal
2k x 2k camera sufficient
for adequate sampling
Piston, Tip, and Tilt: Examples
Y – tilts
opposite signs
Signal
X – tilts
opposite
signs
Features
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Phase
Piston only
X – tilts
same signs
Antisymmetry
axis Y
Antisymmetry
axis Y
Antisymmetry
axis X
Symmetry
axis Y
AO Simulations on OWL.
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125 sub-apertures across pupil, 11198 actuators on M6
Bright NGS on-axis, 1 kHz frame-rate, ~1 sec of real-life PSF
4 ms coherence time, 0.5’’ seeing (at 0.5 mm)
OWL pupil + cophasing M1 & M2: 35 nm WFE RMS each
K band, Strehl ~70%
Atmosheric Wavefront
Illumination on the pyramid WFS
MCAO simulation
2 arc minutes field, l=2.5 mm
2 adaptive mirrors, 8000 actuators each
3 guide stars
Sqrt stretch
Adaptive mirrors
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LBT – 911 mm diameter,
672 actuators
MMT – 642 mm diameter,
336 actuators
Adaptive mirrors
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Capacitive sensors (ref.plate)
(MMT336) aspherical shell
642mm dia.
2mm thick
Magnets
(12mm diam.)
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Extreme AO
High performance adaptive optics at visible
wavelength
Need for 105-106 actuators  MOEMs
Time scale : beyond 2015
Some effort going on but need to ramp up
Positive factor: limited stroke necessary, large
deformable mirrors act as first stage
Technology review, design, production & testing of
demonstrators foreseen in OWL Phase B
Adaptive Optics
IR Deformable Mirrors
IAU Symposium 225 - Lausanne, July 2004 - - Slide 35
Diameter
Actuator spacing
Today
2008
2015
2019
LBT (JWST)
Prototype
OWL 1st Gen.
2nd Gen.
1-m (2-m)
30 mm
0.3-m
15 mm
2-m
15-25 mm
3.2-m
20-25 mm
XAO corrector
Detector
Moems/Pzt
256x256 ?
AO real time control
Reference stars
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512x512
1kx1k
Almost OK
NGS (LGS)
NGS
High sky coverage in the near-IR (better filling of metapupil)
 LGS needed ~2018; lower number of LGS,
 Cone effect requires novel approaches e.g. PIGS (Ragazzoni et al)
NGS / LGS
Telescope performance (wind)
Tracking : low concern

IAU Symposium 225 - Lausanne, July 2004 - - Slide 36
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M2 flat ! Design insensitive to
M2 lateral decenters
Structural design privileges
M2 lateral decenter over M2 tilt
Corrector at very stiff location
(Pupil shape outdated)
DYNAMIC ANALYSIS
Worst caseS combined (orientation), 10 m/s, conservative drag coefficients
Maximum mean displacements out of worst load cases
Mirror
M1
M2
Piston (uz)
[mm]
-0.216
-0.336
Tilt (rotx)
[arcsec]
0.420
1.680
Decenter (uy)
[mm]
-0.129
-1.132
Wind
MODELLING & TESTING
Limited confidence in CFD (Results suspiciously good !)
Wind measurements at Jodrell Bank (2004)
Wind tunnel testing (2004)
Analysis & modelling
Courtesy PSP
Wind (pressure distributions)
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ACCELERATED - ACTUAL ELAPSED TIME 150 SECONDS
M1
Corrector
M2
Wind – design options
1.
2.
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3.
4.
5.
6.
7.
Higher local stiffness (substructure supporting segments)
 increases resistance to high spatial frequencies
Use of SiC segments
 higher M1 & M2 bandwidth
Embedded variable wind screens (up to z~30o)
Increase M4 (active mirror) bandwidth ~2-5 Hz
(VLT M1 support dimensioned for 1 Hz)
Increase range of M6 adaptive correction
Operational constraints
Site selection
… required
for AO anyway
Variable wind screen embedded in the
azimuth structure (notional design);
M2 wind screen not shown
Cost estimate (capital investment, 2002 M€)
SUMMARY
OPTICS
406
Primary & secondary mirror units
355.2
M3 unit
14.4
M4 unit
21.4
M5 temporary unit
M6 temporary unit
5.3
10.1
ADAPTIVE OPTICS
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MECHANICS
MEuros
110
M5/M6 design & prototypes
10
M6 AO unit
25
M5 AO unit
XAO units
LGS
35
20
20
Diffraction-limited instrumentation
(acceptable étendue !)
Assumes “friendly site”
 Average seismicity (0.2g)
 Moderate altitude
 Average wind speed
 Moderate investment in infrastructures
185
Azimuth
53.8
Elevation
34.9
Cable wraps
Azimuth bogies (incl. motors)
Altitude Bogies & bearings
Mirror shields
Adapters
Erection
CONTROL SYSTEMS (*)
Telescope Control System
M1 Control System
M2 Control System
Active optics Control System
CIVIL WORKS
5.0
14.7
5.7
15.0
6.0
50.0
17
5.0
8.0
2.0
2.0
170
Enclosure
40.4
Technical facilities
35.0
Site infrastructure
25.0
Concrete
70.0
INSTRUMENTATION
50
INSTRUMENTATION
Total without contingency
50
939
938.9
(*) High level cs only; local cs included in subsystems
Cost estimates (industrial studies)
Primary & secondary mirror segments; 1.8-m; polished, prices ex works.
SiC (2 suppliers A and B) with overocatings (3 suppliers 1, 2, 3)
Glass-Ceramics (2 suppliers C and D)
Polishing: 2 suppliers, only one shown (both agree within 10%)
2002 ESO
ESTIMATE
Polishing
Overcoating
Blanks
Total cost
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Blanks:
SiC A + Overcoating SiC B + Overcoating SiC B + Overcoating
1
2
3
Glass-ceramics C
Substrate & polishable overcoating
Glass-ceramics D
IAU Symposium 225 - Lausanne, July 2004 - - Slide 42
Optimized geometry (interface optics-mechanics)
All parts fitting in 40-ft containers
1.6-m all-identical segments (~3000 units),
single optical reference for polishing
12.8-m standard structural modules
(integer multiple of segment size)
Friction drive (bogies), hydraulic connection
Cost vs quantity
Industrial data
Applies to conceptually simple items
(e.g. segments, structural nodes)
1.00
VLT M1 polishing (4 units)
COST FACTOR
IAU Symposium 225 - Lausanne, July 2004 - - Slide 43
0.80
0.60
OWL segments
(industrial studies)
0.40
0.20
0.00
1
10
100
Number of units
1000
10000
IAU Symposium 225 - Lausanne, July 2004 - - Slide 44
Polishing: factory implementation
Size (area) comparable to VLT 8-m production facility
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Meanwhile …
ECM
BOOSTEC
IAU Symposium 225 - Lausanne, July 2004 - - Slide 46
• Phase C/D approval 2010
• 8-m mirrors need 6 years
 First light early 2016
 Start of science 2017, 60m
BUT:
long lead items highly standardized
 multiple supply lines possible
 faster integration possible
 ALTERNATIVE ALLOWING FIRST LIGHT IN 2014 (TBC) IS
UNDER EVALUATION
2020
2015
2010
2005
2000
Timeframe
Phase A
IAU Symposium 225 - Lausanne, July 2004 - - Slide 47
Phase A review
ELT Design Study
APE on sky
Phase B
Site selection
First light (50-m)
Completion
Phase C/D
Start of science (60-m)
Groundbreaking
Driven by funding, not by technology
IAU Symposium 225 - Lausanne, July 2004 - - Slide 48
Planned studies 2005 - OWL phase A
Conceptual design of M6 adaptive subunit
Storage and postprocessing of the Jodrell Bank data
Feasibility study for wind tunnel measurements
Wind tunnel measurements (Jodrell Bank model)
Feasibility study for CFD simulations
CFD simulations
Dynamic Analysis of M1 / Corrector M3-M6 Control
OWL Instruments Conceptual Design Studies
Vibration dampers (local modes)
Optimization runs of the mechanical structure
I/F with concrete
Feasibility study M4 figuring / CGH Conceptual Design
ELT Design Study
The R&D part of a phase B
IAU Symposium 225 - Lausanne, July 2004 - - Slide 49
Objectives
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Technology development towards a European ELT
Preparatory work for observatory design
Top level requirements
Academic & industrial synergy
Design-independent
Proposal to EC within FP6 - Approved
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39 partners, 47 WPs / Tasks
42 M€ total, 22 M€ requested
Timescale 2005-2008
IAU Symposium 225 - Lausanne, July 2004 Slide 50
ELT Design Study Proposal
 The R&D part of a phase B
 Objectives
–
–
–
–
Technology development towards a European ELT
Preparatory work for observatory design
Top level requirements
Academic & industrial synergy
 Design-independent
 Proposal to EC within FP6 - Approved
– 39 partners, 47 WPs / Tasks
– 42 M€ total, 22 M€ requested – 8 M€ granted
– Timescale 2005-2008
 ESO as coordinator
 Contract currently under negotiation with EC
IAU Symposium 225 - Lausanne, July 2004 Slide 51
Matrix structure
WP/Task (47)
1
Participants (39)
A
B
C
...
Z
WP budget
2
3
4
5
…
WP budget
WP budget
WP consol.
tool
46
47
Part.
budget
Part.
budget
Part.
budget
Budget prep. tool
IAU Symposium 225 - Lausanne, July 2004 Slide 52
Project Organization
IAU Symposium 225 - Lausanne, July 2004 Slide 53
Shares, in % of total estimated
budget
International
organization
38%
Industry
22%
Institute /
university
40%
UK Australia
Belgium
Sweden 5.9%
3.8%
4.5%
CH
4.8%
1.4%
Spain
France
10.6%
16.4%
NL
1.3%
Germany
2.2%
Italy
10.4%
Israel
0.2%
Ireland
0.5%
ESO
International
38.0%
IAU Symposium 225 - Lausanne, July 2004 Slide 54
Engineering WP - overview
No
Title
01000 Project Management
04000 Wavefront Control
05000
06000
07000
08000
09000
10000
11000
12000
13000
Topics
Breadboard / prototypes
[includes overall system / project engineering]
Phasing, actuators, metrology,
APE, WEB (wind)
PSF properties, high contrast
imaging, error budgeting
Optical fabrication
SiC, opt. finishing, Al mirrors, coatings 8 x 1-m SiC segments
Mechanics
Composite materials, MagLev,
Friction Drive breadboard
Friction drives
Control
Support to other WPs (APE, WEB)
Enclosure & infrastr.
Enclosure concepts, renewable
energies, infrastructures, wind tunnel
Adaptive Optics
WFE on 100-m scale, AO units
DM prototypes
designs, large DMs, novel concepts,
algorithms, simulations
Observ. & science ops. System operations (studies, requirements)
Instrumentation
Point designs, ADC
Site characterization
Site parameters, measurements,
[site testing equipment]
modeling, large scale atmo. properties
System layout,
Integrated modelling tools, support to
analysis & modelling
other WPs
From concept to sky testing: APE
Active Phasing Experiment
IAU Symposium 225 - Lausanne, July 2004 - - Slide 55
Segmenting the VLT
Laboratory & on-sky
evaluation of up to
3 phasing techniques
Integration of
phasing into
global wavefront
control
On-sky by 2007
IAU Symposium 225 - Lausanne, July 2004 Slide 56
WEB
IAU Symposium 225 - Lausanne, July 2004 Slide 57
Silicon Carbide prototypes
 1-m class, 8 pcs., different overcoatings
 4 blanks already at ESO
 Explore overcoating & figuring processes,
check for bimetallic effects
 Advantages
– Stiffer, lighter, better thermo-mechanical
properties (than glass)
– Higher control bandwidth (position)
– Hardness
– Lighter, stiffer telescope structure
– ~20 years of development, space-qualified
– Potentially cost-effective if appropriate design
 BUT
– Needs qualification for segmented apertures
IAU Symposium 225 - Lausanne, July 2004 Slide 58
Friction drive breadboard
Mandatory – Hydraulic pads / tracks not an option !
Alternative: magnetic levitation - TBD
IAU Symposium 225 - Lausanne, July 2004 Slide 59
Overall schedule
IAU Symposium 225 - Lausanne, July 2004 - - Slide 60
ELT Design Study – subcontracts (planned)
Subject
Contact
email
Design & testing of 18 segments
position actuators
E. Brunetto,
ESO
[email protected]
Feasibility study for magnetic
levitation (telescope kinematics)
E. Brunetto,
ESO
[email protected]
Conceptual design of opening
enclosure for a 50- and a 100-m
telescope
G. Pescador,
GRANTECAN
[email protected]
Wind studies – CFD
L. Noethe, ESO
M. Quattri, ESO
[email protected]
[email protected]
Wind studies – wind tunnel
Idem
Idem
Site characterization equipment
J. Vernin,
LUAN
[email protected]
Contacts @ ESO
OWL
IAU Symposium 225 - Lausanne, July 2004 - - Slide 61

J. Strasser,
Telescope Systems Division,
Project Controller
 P. Dierickx,
Project Engineer / Manager
 R. Gilmozzi,
Prime Investigator
 E. Brunetto
Optomechanics
[email protected]
[email protected]
[email protected]
[email protected]
ELT Design Study

P. Dierickx
Project Manager
 R. Gilmozzi
 Project Coordinator
[email protected]
[email protected]