The Thirty Meter Telescope Jerry Nelson, UCSC 2005 December 8.

The Thirty Meter Telescope

Jerry Nelson, UCSC

2005 December 8

2005 December 8 JEN TMT status 2

Contents

• Lessons of History and Predicting the Future

• Scientific Potential of TMT• TMT Organization• TMT conceptual design

– Overall structure– Optical design– Primary mirror– Segment geometry– Segment fabrication– Active control– Enclosure

• Adaptive Optics• Status

QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.


Predicting the future

• Proposed Future Ground Based Telescopes– California Extremely Large Telescope (CELT) 30 m– 20/20 (University of Arizona study) 30 m equivalent

– Giant Magellan Telescope 20m– Euro 50 (Lund University study) 50m– OWL (ESO study) 100m (<60m)– TMT (merger of CELT, GSMT, VLOT) 30m

• Major Issues (mainly cost)– mass production of optics– active control– adaptive optics – structural issues– enclosure/ weather protection


Science Potential for TMT

• Increased angular resolution– With AO can reach 0.007 arc second resolution (100x improvement)

– Study morphological details of most distant galaxies (cosmology)

– Study details for star and planet formation– Study stellar evolution in globular clusters– Quasars and Active Galactic Nuclei (black holes)– Solar system objects

• Increased light gathering power– With TMT can collect 9x the energy from an object (over Keck)

– Spectroscopy of most distant objects known– Planet searches and their study


Scientific Potential

• Seeing limited observations– 0.3-1.0 µm– Scale 2.18 mm/arc second (f/15)– Wide field of view available: 20 arcminutes

• Diffraction limited observations– 1-25µm, mainly 1-2.5µm– Thermal IR possible, but not most important– At 1 µm angular resolution of 7 mas– Resolution element size: 15µm (at f/15, 1 µm wavelength)

– Large field of view: 1 arc minute at 1 µm with multi conjugate AO


Thirty Meter Telescope

• TMT is a project to build a 30-m telescope• UC and Caltech are partners (CELT) + Canada + AURA

• Design and prototyping money is ~ here • $70M total needed

– $35 UC+Caltech (CELT) from Moore Foundation– Canada contributes $17.5M– AURA should contribute $17.5M (highly uncertain)

• Site is unknown (several candidates being studied)

• Project manager (Gary Sanders from LIGO)• Project scientist (J. Nelson)• Project office in Pasadena


TMT Project OrganizationTMT BoardEd Stone

Project ManagerGary Sanders

FacilityPaul Gillett, Acting

TelescopeLarry Stepp

Instrumentation Operations Design

Project ScientistJerry Nelson

System EngineeringGeorge Angeli

Business ManagerDavid Goodman

Observatory ScientistDave Silva

Science Advisory CommitteePaul Hickson, Chair

OutreachDoug Isbell

IT

Adaptive OpticsBrent Ellerbroek

InstrumentsDavid Crampton

Observing Design

Observatory SoftwareJennifer Dunn, Acting

StructureChris White

OpticsDan Blanco, Acting

ControlsMark Sirota

Site SelectionPaul Gillett

EnclosureJoeleff Fitzimmons, Acting

Summit FacilitiesDouglas Gray

Support FacilitiesDouglas Gray

ES&H/QA


Original Point Designs

GSMT CELT VLOT

http://www.hia-iha.nrc-cnrc.gc.ca/VLOT/index.html

http://celt.ucolick.org/www.aura-nio.noao.edu/


Site Selection

• We have a team of research scientists studying potential sites for TMT

• Sites are being studied in Chile, San Pedro Martir (Baja) and Mauna Kea, HI

• Measurements include– Weather (cloudiness, wind, temperature, humidity, dust)

– Atmospheric seeing (total seeing with DIMM’s, profile with MASS and with SODAR’s)

• Expect to select qualified sites in 2007• Hope for competition between qualified sites to host TMT


TMT Optical Design

• Primary is 30m in diameter– 738 segments, 1.2 m dia each– Shape actively controlled (segment piston, tip, tilt)

– f/1.0 ellipsoid• Final: f/15 Aplantic Gregorian

– Secondary 3.5m in diameter (concave)– 20 arc minute field of view with 0.5 arc second images

– 1 arc minute FOV with 0.001 arc second images (design)

– Science from 1° to 65° zenith angle• Instruments at Nasmyth platforms

– Articulated tertiary allows direct feed to multiple instruments with no additional optics (3 mirrors total)

– 2 platforms: 15x30 m– Possible lower or upper platforms

33.32m

3.32m

3.58m

3.5m

30m

20mTMT Optics


30m Primary Mirror Concept

738 1.2m segments each 0.040m thick

TMT

Keck


TMT Reference Design

60m

20m

32m

40m

2m

34m


Segment Fabrication

• Segments are off axis sections of ellipse– Requirements: ~ 20 nm rms surface (better than Keck)

– ~ 90 µm deviation from sphere (Keck was ~ 100µm)• Fabrication study contracts (3) in place: Sagem, Zygo, ITT-Tinsley– Stressed mirror polishing (oap to sphere) favored by all

– Planetary polishing to increase efficiency (simultaneous polishing of multiple mirrors)

– Low expansion material will be used– Final figure corrections with ion figuring likely

• Segment warping harnesses (WH)– Will remove low spatial frequency segment errors caused by testing errors, polishing errors, support errors, thermal errors, alignment errors

– Will ease tolerances (and costs) of fabrication, etc


Planetary polishing to Planetary polishing to produce 800 segmentsproduce 800 segments

Full stressing fixture

Planetary Stressed Mirror Polishing


Passive segment support

• Design work contracted to Hytec (Los Alamos)

• Basic requirements– Support segments against gravity and thermal disturbances

– Maintain desired surface figure to ~ 5 nm rms– Accurately maintain segment in desired location – Provide interface between actuators and mirror– Provide stiff (50Hz natural frequency) support– Allow for handling of segments for coating and recoating

– Allow for warping harnesses to adjust low order shape of segment

– Inexpensive to design, build, install, adjust– Zero maintenance for life of telescope


SSA Concept


Active Control

• Active control algorithm (details by G. Chanan)– Same idea as Keck: edge sensors, actuators, least squares fitting

– Error propagation calculated to be acceptable: ~ 10x sensor noise

• Edge sensors – Relative to Keck, want lower cost, avoid mechanical interlace

– New sensor design is still capacitive, but ~ on edges of segment

– Design by Mast and LBL engineering

• Actuators– Relative to Keck, want lower cost, higher stroke– Keck actuators used roller screw/hydro reducer (position actuator)

– TMT contract with Marjan to design and build a voice coil based force actuator. This should have 4x stroke and be ~ 1/4 Keck cost


Active Control Summary

Selected a = 0.6 m for segment size

Item Keck TMT

segment size 0.9m 0.6m

# segments 36 738

# edge sensors 168 4212

# actuators 108 2214


Actuator Actuator (piston)(piston)

Sensor (measures height Sensor (measures height difference)difference)

Principle of active control with edge sensorsPrinciple of active control with edge sensors

ssPP11

PP22

PP33

PP55

PP44

PP

66

s=a1P1 +a2P2 +a3P3 +a4P4 +a5P5 +a6P6PP99

PP77

PP88

Sensor signal depends only Sensor signal depends only on motion of two on motion of two neighborneighbor

segmentssegments

a a are constant coefficients that are constant coefficients that depend only on geometrydepend only on geometry


Mirror Segment

7.5 cm

Sensor Paddle

Sensor BodySensor Mount

Conducting Surfaces 2 mm

L

R = 35 m

Keck Sensor Geometry


titleProposed TMT Sensor Geometry

Non-Interlocking Sensors


Concept of segment support

Segment

Actuator

Reference Frame

Mirror Cell

Truss

Actuator

Whiffle Tree

Moving Frame


Enclosures

Design options under study (from NIO)


Adaptive Optics for TMT

• First generation– NFIRAOS

• Near IR AO system with rms wavefront error ~ 190 nm. Generates Strehl ratio ~ 0.7 at 2µm

• Hoping to upgrade to rms wavefront ~ 130 nm sometime after first light

• Large sky coverage (>50%)• Na laser guide stars do atmospheric tomography• Small field of view: 10”-1’• Remember diffraction limit at 1µm is 0.007 arcsec

– MIRAO• 5-25µm diffraction limited system


Science Instruments

• Seeing limited instruments (studies underway)– HROS: high resolution optical spectrometer- ~ HIRES

– WFOS: wide field optical spectrograph ~ LRIS, DEIMOS multi object spectrometer, Fov ~ 20 arc min

• Diffraction limited instruments (studies underway)– IRIS– MIRES– NIRES– WIRC– MOAO


Construction Phase

• Approval to start ($$ available) Jan 2008• Primary mirror detail design review Apr 2008• Site Development FDR Apr 2008• Complete enclosure Feb 2012• Complete telescope installation Oct 2012• Begin segment installation Aug 2012• First light with 1/4 segments Jul 2013• All segments installed, phased Apr 2014• Begin TMT science Jan 2015


Development phase

• Conceptual design review May 2006• Cost review Sept 2006


TMT AO Development Program

• DDP program addresses TMT AO architecture, design and technology development

• Key technologies and demonstrations– MEMS– Lasers– Infrared tip-tilt wavefront sensing– Open loop control– Tomography– Wavefront sensor– Adaptive secondary technology

• AO development addressed by an $11.7M DDP plan


• end


TMT Experience with Adaptive Optics

UC Lick Palomar

Keck

CFHT

Gemini


40 x 40 arcsecond mosaic, color-composite NIRC2 image (at ~2.2 um)of the Galactic Center using Keck Laser

Ghez (UCLA) & collaborators

Adaptive Optics has come of age!

Gemini Hokupa’a/QUIRC image of Galactic Center. Expanded view shows IRS 13E & W in Kp


NGS / LGS Comparison

NGS-AO bestJune 2004 (4 nights)46 best x (0.50x120)SR=0.34, FWHM=92 mas

LGS-AO26 July 20048 x (0.25x120)

SR=0.75, FWHM=82 mas

GC


Courtesy: L. Sromovsky

Keck AO Imaging of Uranus


Representative Construction Budget

Construction Phase ($800M)* Possible NSF contribution

– 2008 $50M $12-25M– 2009 $100M $25-50M– 2010 $160M $40-80M– 2011 $180M $45-90M– 2012 $140M $35-70M– 2013 $100M $25-50M– 2014 $70M $18-35M

*Current range of estimates $600M-$800M


CELT AO Approach

• We are exploring a staged AO implementation, to match the evolving technology

• Each level change has a smaller wavefront error

• Each level change requires more and better deformable mirrors

• Each level change requires more laser beacons

• Each level change delivers better image quality

Strehl Ratio vs Wavelength

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00Wavelength (microns)

Strehl Ratio "floor" 248 nmrms"requirement"180 nm rms"goal" 133 nmrms

248180133

J H K

Strehl Ratio vs Wavelength

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00Wavelength (microns)

Strehl Ratio

248180133

J H K

rms nm of residual error


MCAO technology needs

5 cameras, 5e- rms

3 cameras, 5e- rms

3 each with Today’s

128x128 x 250Hz, 20e- rms read noise

Near IR WFS detectors

9 cameras 256x256 x 1kHz

7 cameras, 256x256 x 1kHz

5 each with Today’s

128x128 x 1kHz

Visible WFS detectors

10x Today3x TodayToday’s1 x 109 operations/sec

Real-time computing

4DMs, 21,000 actuators

3 DMs, 9,000 actuators

2 DMs, 2,500 actuators

1 DM, 900 actuators

Deformable mirrors

9 lasers, 15W m/m pulsed, AO on uplink

7 lasers, 15W m/m pulsed

5 each with Today’s Technology

2W CW dye, 8W micropulse/ macropulse

Na guide star lasers

133 nm180 nm248 nmTodayTechnology


TMT Reference Design

Following a detailed engineering study, the partnership has agreed on a single basic reference design:– 30m filled aperture, highly segmented– aplanatic Gregorian (AG) two mirror telescope– f/1 primary– f/15 final focus– Field of view 20 arcmin– Elevation axis in front of the primary– Wavelength coverage 0.31 – 28 µm– Operational zenith angle range 1° thru 65° – Both seeing-limited and adaptive optics observing modes

– First generation instrument requirements defined– AO system requirements defined

The Thirty Meter Telescope Jerry Nelson, UCSC 2005 December 8.

Documents

Transcript of The Thirty Meter Telescope Jerry Nelson, UCSC 2005 December 8.