TMT Instrumentation and Performance...May 24, 2007 TMT.INS.PRE.07.012.REL01 1 TMT Instrumentation...

May 24, 2007 TMT.INS.PRE.07.012.REL01 1

TMT Instrumentation and Performance:

A Handbook for the

July 2007 TMT Science Workshop


Important Note

Feasibility studies for all TMT instrument concepts were conducted in 2005-2006. These studies included more than 2000 pages of scientific and technical information, and this handbook is therefore a highly condensed summary of the planned TMT instrumentation.

If the information you require to assess the scientific possibilities of TMT for your research is not found in this Handbook, please do not hesitate to contact the TMT instrumentation group:

David Crampton ([email protected])Luc Simard ([email protected])

Good luck!

mailto:[email protected]:[email protected]:[email protected]:[email protected]


TMT


TMT Basic Characteristics

Collecting area: filled aperture with 30m circumscribed diameter, f/15 Ritchey-Chrétien optical design

Wavelength range: 0.34 - 28 µm (goal 0.31 - 28 µm)

FOV: 15’ diameter (unvignetted), 20’ (minimal vignetting)

Delivered image quality: – Seeing-limited: 80% encircled energy at 0.5 µm = 0.237 mas

including image jitter– AO-assisted: 187 nm rms wavefront error on axis over 2’ diameter

corrected FOV (Current AO systems on 8-10m class telescopes deliver 240 - 380 nm rms)


TMT SAC Instrument Suite


TMT Discovery Space


TMT Instrumentation

TMT instruments are currently divided into two categories: “Early Light” and “First Decade”

Early light instruments are expected to be available at the start of TMT science operations. This category includes the following instruments:

– Wide-Field Optical Spectrometer (WFOS)– InfraRed Imaging Spectrometer (IRIS)– InfraRed Multi-slit Spectrometer (IRMS)

First decade instruments are expected to be commissioned within the first decade of TMT operations. They include (in no particular order):– Planet Formation Instrument (PFI)– High-Resolution Optical Spectrometer (HROS)– Mid-InfraRed Echelle Spectrometer (MIRES)– InfraRed Multi-Object Spectrometer (IRMOS)– Near-InfraRed Echelle Spectrometer (NIRES)


First Decade Instrumentson TMT Nasmyth Platforms


TMT Adaptive Optics

Conventional natural guide star AO: Very limited sky coverage (not enough bright natural stars)Single laser guide star AO: Poor performance due to the cone effect (laser guide star too close to telescope aperture)Laser Tomography AO (LTAO): – Multiple laser guidestars used to defeat the cone effect– Good AO performance over a narrow field of view

Multi-conjugate (and specifically dual-conjugate) AO (MCAO)– Multiple (two) deformable mirrors enlarge the corrected field-of view – Uniform image quality improves photometry and astrometry

Multi-Object AO (MOAO): Separate correction of multiple small objects (like distant galaxies) within a larger fieldGround-layer AO (GLAO): Moderately “improved seeing” over significantly larger fields of viewExtreme AO (ExAO): High contrast imaging/spectroscopy


Mapping AO Modes to Instrumentation Capabilities

Image Quality

High Contrast

Diffraction- Limited

Enhanced Seeing

Seeing-Limited

FoV

2”

5-10”

0.5-2.0’

5’

10-15’

ExAO

MOAO

GLAO

MCAO

LTAO

NarrowFieldNIR

IRMOS

MIRESPFI

WFOS(SRD)

HROS(SRD)

Study?


Early Light AO Architecture for TMTSupports Narrow-Field Instruments Using

Existing/Near-Term Components/Concepts

ConventionalSecondary

Laser GuideStar Facility

• 3-6 sodium laser guidestars• 3 50W, CW lasers

MCAO(NFIRAOS)

LTAO• 3 LGS WFS• Current piezo DM technology

• 6 LGS WFS• 2 high-order piezo DMs

Narrow-fieldNear IR

Instruments

Mid IRInstruments


Early Light Instrumentation


Wide Field Optical Spectrometer (WFOS)

– Multi-object spectroscopy over two 4.5’x5.4’ fields (that extend to 17’ diameter at corners)

– Wavelength range: 0.34-1.1µm. ADC included– Field of view: 46 arcmin2; Total slit length: 650 arcsec– Image quality: ≤ 0.2 arcsec FWHM over any 0.1µm – Spatial sampling: 0.07 arcsec per pixel– Spectral resolution: R=5-5000 for 0.75” slit; goal: 150-7500

WFOS field layout

Back to Instrument list


WFOS Science

An IGM Tomographic Surveyor

Given that TMT will go ~ 2 mag deeper than 8-10m class telescopes, and background UV-bright galaxies will become usable beacons, sky surface density of sightlines will be ~200x higher

An individual galaxy halo will therefore be probed through multiple sightlines

(R. Cen, Princeton U.)


WFOS Performance


Narrow-Field IR AO System (NFIRAOS): TMT’s Early Light Facility AO System

Strehl Ratio Band SRD (120 nm) Baseline (177

nm) Baseline + TT

R 0.313 0.080 0.052 I 0.411 0.145 0.105 Z 0.566 0.290 0.236 J 0.674 0.424 0.366 H 0.801 0.617 0.569 K 0.889 0.774 0.742

Dual conjugate AO system– Order 61x61 DM and TTS at h=0 km– Order 75x75 DM at h=12 km– Better Strehl than current AO systems

Can feed three instruments Completely integrated system

Fast (50% sky coverage at galactic poles


InfraRed Imaging Spectrometer(IRIS)

An integral field spectrometer and imager working at the diffraction limit:Fed by NFIRAOS (Narrow Field IR AO System)Wavelength range: 0.8-2.5µmField of view: < 2 arcsec for IFU, up to 10” for imaging modeSpatial sampling: 4 mas per pixel (Nyquist sampled (λ/2D)) over 4096 pixels for IFU); over 10x10 arcsec for imaging

– Plate scale adjustable 0.004, 0.009, 0.022, 0.050 arcsec/pixel – 128x128 spatial pixels with small (Δλ/λ ≤ 0.05) wavelength coverage

Spectral resolution – R=4000 over entire J, H, K, L bands, one band at a time– R=2-50 for imaging mode

Two IFU paths: lenslet-based (for better wavefront quality) and slicer-based (for higher sensitivity)Parallel imaging: goal



Motivation for IRIS

Should be the most sensitive astronomical IR spectrograph ever built.Unprecedented ability to investigate objects on small scales.

0.01” @ 5 AU = 36 km (Jovian’s and moons) 5 pc = 0.05 AU (Nearby stars – companions) 100 pc = 1 AU (Nearest star forming regions) 1 kpc = 10 AU (Typical Galactic Objects) 8.5 kpc = 85 AU (Galactic Center or Bulge) 1 Mpc = 0.05 pc (Nearest galaxies) 20 Mpc = 1 pc (Virgo Cluster) z=0.5 = 0.07 kpc (galaxies at solar formation epoch) z=1.0 = 0.09 kpc (disk evolution, drop in SFR) z=2.5 = 0.09 kpc (QSO epoch, Hα in K band) z=5.0 = 0.07 kpc (protogalaxies, QSOs, reionization)

Titan with an overlayed 0.05’’ grid (~300 km) (Macintosh et al.)

High redshift galaxy. Pixels are 0.04” scale (0.35 kpc). Barczys et al.)

M31 Bulge with 0.1” grid (Graham et al.)

Keck AO images


IRISConcept

F/15 AO Focus

Imager Filter Wheels

Common reimager camera lens

LensletArray

Alternate GratingsOn Turret

Imager– 4K detector, 15” square field

Integral Field Spectroscopy– Lenslet option:

128x128 lenses (250 micron pitch)1000 pixel spectral length (2 pixels per resolution element)Bandpass: 5% per exposure

– Image Slicer option88 slicesLarger bandpass but poorer wfe

WIRC precise photometry and astrometry can be done with IRIS but with smaller field

Focal plane layout

IRIS will reach point sources as faint as K = 28 (KAB = 30) (3σ) in 3 hours.


InfraRed Multi-Slit Spectrometer(IRMS)

Clone of Keck MOSFIRE– Multi-slit NIR imaging spectro: Step 0 towards IRMOS– 46 slits: width ≥ 160 mas, length= 2.5”– Deployed behind NFIRAOS

2’ field 60 mas pixels Encircled energy (EE) good (80% in K over 30”)

– Spectral resolutions up to 5000– Full Y, J, H, K spectra

Imager as well

Slit width

Entire NFIRAOS 120” fieldBack to Instrument list

http://www.astro.ucla.edu/~irlab/mosfirehttp://www.astro.ucla.edu/~irlab/mosfire


MOSFIRE Concept

http://www.astro.ucla.edu/~irlab/mosfirehttp://www.astro.ucla.edu/~irlab/mosfire


IRMS Slit Unit & Field

2’ diameter

Detector area

CSEM configurable slit unit• Slits formed by opposing bars• Designed for JWST (backup for MEMS shutters)

• Original concept proposed by HIA (Erickson 2003)• Designed for 35K operation• Minor mods for MOSFIRE

• Reconfigurable in ~3 minutes


IRMS Spectra

Full Y, J, H, K spectra with R ~ 5000 with 160mas (2 pix) slits in central ~1/3 of field


IRMS Performance

Whole 120” field

Encircled energy curves showing the NFIRAOS wide field performance in J, H and K with tomographic reconstructor parameters tuned to optimize image quality over a 30’’ field (left-hand panels) and a 120” (right-hand panels). The minimum (Nyquist-sampled) IRMS slit width is 160 mas, and it thus encloses light within a radius of 80 mas.


First Decade Instrumentation


Planet Formation Instrument (PFI)

Wavelength range: 1-2.5µm, goal 1-4µmField of view 0.7 arcsec radius - goal is 2 arcsecPlanet detection contrast

– 10-8 @ 50 mas, goal of 10-9 @ 100 mas (5-sigma detection in 2hr integration with I < 8 parent star magnitude)

– 10-6 @ 30 mas, goal of 2x10-7 @ 30 mas (5-sigma detection in 2hr integration with H < 10 parent star magnitude)

Critically sampled at H-band (0.0035 arcsec pixels), goal is at J-bandSpectral resolution, full FOV, IFU: R = 50, goal 100Spectral resolution, partial FOV, IFU: R = 500, goal 1000Polarization: simultaneous dual channel



PFI Science



PFI Block Diagram


High Resolution Optical Spectrometer(HROS)

Seeing limited optical spectrometerWavelength range: 0.31 - 1 µm (0.3 - 1.3 µm goal)Field of view: 10 arcsecImage quality: ≤ 0.2 arcsec FWHM at detectorTotal slit length 5 arcsec, separation between ordersSpectral resolution: R=50,000 for 1 arcsec slit, R=90,000 with slicerStability: 1 m/s velocity precision over 10 years


Two HROS concepts were competitively studied as part of the TMT instrument feasibility study phase in 2005 - 2006. One concept (“MTHR”) originated from the UC Santa Cruz (PI: S. Vogt) , and the other concept (“CU-HROS”) was proposed by a University of Colorado team (PI: C. Froning).


HROS Science



HROS “MTHR” Concept (UCSC)

“classic” echelle design 10m x 11m x 4m 1.6m off-axis parabolic

collimators 1.4m camera lenses Echelle:

–3x8 mosaic of gratings–1m x 3.5m–8700 pounds


HROS “MTHR” Performance


CU-HROS Concept

Completely new concept, using high performance dichroics

Transmission of actual Barr filter for ACS is ~95%


Dichroic Tree – CU-HROS array performance model

Net efficiency after 5 reflections/transmissions ranges from 70-77% after degrading predictions to match spec (>95% transmission/reflection)Sharp transition edges (3-5nm) reduce data loss at bin edgesHigh frequency ripples do not line up


CU-HROS Performance


Mid-IR Echelle Spectrometer (MIRES)

Mid-IR Diffraction Limited Spectrometer, fed by MIRAO (AM2?)8-18µm, 5-28µm goalField of view: 10 arcsecSlit length: 3 arcsec sampled at 0.04 arcsec / pixelSpatial sampling

– 0.017x0.017 arcsec pixels (Nyquist-sampled at 5 µm); 2K detectorSpectral resolution

– 5000< R


MIRES Science


MIRES Concept

AO WFS

MIRES

AURA/NOAO

and

UH IfA


Infrared Multi-Object Spectrograph(IRMOS)

Deployable IFU spectrometer fed by Multiple Object AONIR: 0.8-2.5µmFoV: IFU heads deployable over 5 arcmin fieldImage quality: diffraction-limited images, tip-tilt ≤0.015 arcsec rmsSpatial sampling– 0.05x0.05 arcsec pixels, each IFU head 2.0 arcsec FOV, ≥ 10 IFU units

Spectral resolution – R=2000-10000 over entire J, H, K bands, one band at a time– R=2-50 for imaging mode


Two IRMOS concepts were competitively studied as part of the TMT instrument feasibility study phase in 2005 - 2006. One concept (“TiPi”) originated from Caltech (PI: R. Ellis) , and the other concept (“UF”) was proposed by a University of Florida team (PI: S. Eikenberry).


IRMOS Science

For studies of galaxy assembly, the power of IRMOS on TMT will transform the z~3 universe into our own backyard


TiPi Pickoff ConceptInnovative tiled array of mirrors at a relayed, partially compensated focal plane feeds 16 optical trains (with MEMS DMs) to integral field spectrographs

TiledMOAO

focal-plane

4 of 16 d-IFUspectrograph units

Flat 3-axissteering mirrors

OAPs

MEMS-DMs


TiPi Performance


IRMOS-UF Pickoff Concept

Individual probes feed individual spectrographs, each probe contains a miniaturized MOAO system


IRMOS-UF Performance


Near IR Echelle Spectrometer(NIRES)

Diffraction limited spectroscopy, fed by NFIRAOS

Wavelength range: 1 - 2.4µm

Field of view of acquisition camera: 10 arcsec, 0.0035 arcsec/pixel

Slit length: 2 arcsec

Spatial sampling: Nyquist sampled (λ/2D)

Spectral resolution: 20,000


NIRES ScienceIntergalactic medium beyond z = 7– Lyman-alpha systems– GRB observations

Detailed abundance studies in Local Group stars– Chemical evolution in the Galactic Center– Chemical evolution in Local group Galaxies

Abundance, chemistry and kinematics in star/planet-forming disks– Structure and evolution in planet-forming regions of disks– Structure and Kinematics of Proto-stellar envelopes– Composition of comets

Terrestrial planets around low-mass stars and brown dwarfsCharacterizing extra-solar planets and brown dwarfs:– Probing atmospheres of hot giant and transiting exoplanets– Weather on brown dwarfs


NIRES Concept

NIRES could be similar to existing instruments like Keck NIRSPEC


Wide-field Infrared Camera(WIRC)

Precise photometry and astrometry instrumentWavelength range: 0.8-5µm, goal 0.6-5µmField of view: 30 arcsec, contiguous Image quality: diffraction limited as delivered by AOSpatial sampling: Nyquist sampled (λ/2D)Spectral resolution: R=5-100 with filters

Some WIRC science could be done with IRIS


TMT Instrumentation and Performance...May 24, 2007 TMT.INS.PRE.07.012.REL01 1 TMT Instrumentation...

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