Adaptive Optics Systems: Present State, Scientific Accomplishments, Future Plans:

Transcription

1 Adaptive Optics Systems: Present State, Scientific Accomplishments, Future Plans: A Presentation to Dr. Michael Turner, NSF 21 March 2005 Ver 4.1 (23 March 2005) Prepared by Jay A. Frogel, AURA, for ACCORD 1

2 Outline and Key Points What is Adaptive Optics (AO)? Current status: AO is delivering exciting science now Planned evolution of current AO systems Future need - AO provides a dramatic enhancement in performance for all large (>20-30 meter) telescopes Continuing investment in AO technology will make today s telescopes even more powerful Continued NSF investment in AO developments is critical: it builds on results from the NSF Center for AO at Univ. Cal. Santa Cruz, the recently begun NSF AO Development Program (AODP), and from the Center for Astronomical Adaptive Optics at Univ. of Arizona 2

3 What is AO Adaptive Optics (AO) is a system that corrects the effects of atmospheric blurring by measuring these effects on one or more natural or laser guide stars (NGS or LGS) near the object of interest. We can now deploy AO systems because of significant advances made in optics, detectors, and the power of computers over the past decade. The techniques of AO work best in the infrared, λ > 1µm, where it becomes possible to achieve diffraction limited imaging of celestial sources with large telescopes. AO will provide a dramatic enhancement to the power of any extremely large telescope (ELT) 3

4 Current status of some AO Facilities 4

5 Current status of AO facilities AO systems in near and mid-ir and visible wavelengths (Air Force) now operate on telescopes of all sizes: U. Hawaii, Canada-France-Hawaii, ESO La Silla, Lick, Calar Alto, Mt Wilson, William Herschel Telescope, Palomar, 2 Kecks, 4 VLTs, Subaru, Gemini North, MMT, 2 Air Force telescopes AO systems have demonstrated their ability to: deliver high fidelity, diffraction-limited images enable large gains in sensitivity improve photometric accuracy in crowded fields reduce the size of instruments Crucial synergy has arisen between HST in visible and AO on 8-10 m telescopes in near-ir because they deliver the same spatial resolution 5

6 Some US Observatories with NGSAO or LGSAO Systems Producing Science Now UC Lick CFHT Palomar Keck Gemini MMT 6

7 Examples of Current AO Systems now used to produce science: 7

8 Laser Guide Star AO on Keck Courtesy of Fred Chaffee, Keck Observatory 8

9 Egg Nebulae with Keck LGSAO and HST Egg Nebula Keck LGSAO NIRC platescale 32x32sec color composite image H and Kp Optical HST image Near-IR diffraction limited imaging on Keck = spatial resolution of HST in the visible 9

10 Herbig Ae/Be Stars with LGSAO at Lick The Science: A strongly polarized, biconical nebula 10 (6000 AU) in diameter is discovered around LkHα 198 as well as a polarized jet-like feature associated with the deeply embedded source LkH 198-IR. LkHα 233 shows a narrow, unpolarized dark lane consistent with an optically thick circumstellar disk blocking our direct view of the star. These data show that the lower-mass T Tauri and intermediate mass Herbig Ae/Be stars share a common evolutionary sequence. Three-color LGS AO mosaics of LkHα 198 and LkHα 233. Plotted from left to right are the total intensity (Stokes I), the polarized intensity, P, and the polarization fraction P/I. Red is Ks, green, H, and blue J. The dimmest circumstellar features detected are 1-2x10 4 times fainter than the stellar intensity peaks. (Perrin, et al. 2004) 10

11 AO with Deformable Secondary on the MMT Currently the only AO system that uses a deformable secondary mirror for wave front correction. It is driven by 336 actuators. Advantages of this approach Optically simple with high throughput Low emissivity optimizes operation in the thermal IR At 10 µm MIRAC3 on the MMT has 0.32 PSF FWHM and typical Strehl of 98%. Part of MIRAC3 is BLINC, a nulling interferometer to permit observations of faint circumstellar material around bright stars. 11

12 The MMT Deformable Secondary The MMT adaptive secondary 0.64 m in diameter. Note the thin (2 mm) glass shell ~30 µm away from its thick reference body. It is deformed by 336 voice coils pushing on magnets (dark dots) glued to its back surface. 12

13 Mid-IR AO imaging on the MMT Image of planetary nebulae taken at 9.8 µm and 11.7 µm using MIRAC3, the natural guide star AO camera on the MMT. The white bar in the corner is 1 in length. (Images courtesy of B. D. Oppenheimer in Kenworthy et al. (2004), "Scientific results from the MMT Natural Guide Star Adaptive Optics System", Proc. SPIE, Volume 5490, pp ). 13

14 Multi-laser tomography and ground-layer sensing: Work is Well Advanced at Several Observatories The five laser beams projected on a 1 arcmin radius. The beams are seen above the MMT on the bottom of cloud. Five laser beams from two 15 W lasers propagate from the MMT. Work is underway at the MMT, Gemini, and other observatories to understand and deploy systems for Multi Conjugate Adaptive Optics and Ground Layer Adaptive Optics. 14

15 The Gemini ALTAIR AO System and the search for faint companions to bright stars This image shows that it is possible to search for faint companions around Vega, a V=0 star. Even without using a coronagraph, the ALTAIR PSF at field angles > 3 can achieve contrasts of up to 1 part in 10 8 (5σ detection) as shown by the faint background objects identified by the arrows. This is an improvement of several magnitudes with respect to contrast limits attained by other AO systems worldwide (courtesy René Doyon, U. Montreal). 15

16 Plans for Gemini AO Systems The US share of the Gemini telescopes is a public facility open to all US astronomers. The integrated ALTAIR LGS system will be operational in the second half of 2005 on Gemini- N. It uses a compact 14W fully automated laser system 2006: planned first light for a MCAO system with 50W Na laser on Gemini-S. Developed jointly with CfAO, Keck, and SOR; see illustration at right. The 50W Na laser on the USAF SOR 3.5m telescope. 16

17 MCAO vs. Conventional AO %Sky Coverage LGSAO/MCAO J H 90º Galactic latitude 7/12 16/14 30º Galactic latitude 21/67 44/69 These tables summarize some basic performance parameters of the MCAO system to be implemented on Gemini-S but are typical of the gains to be expected on 8-10m telescopes. K Field of View (diameter arcsec) MCAO CAO Area Gain with uniform PSF 35/24 J x H x 74/82 K x The upper table gives predicted sky coverage at JHK with a single LGS AO system and MCAO at two Galactic latitudes. The lower table compares predicted FOVs over which the PSF is uniform and the resultant areal gain 17

18 Refereed Publications AO Science and Instrumentation 18

19 Science accomplished already with existing AO systems is significant: Imaging and spatially resolved spectroscopy of solar system objects Spatial resolution in the near-ir is ~4 x greater than HST/NICMOS Observations in the thermal IR possible Imaging debris disks proto-planetary systems Discovery and imaging of very low mass stellar companions Measuring proper motions and stellar orbits in the Galactic Center Resolving dense galactic and globular clusters Studying the stellar populations in nearby galaxies Studying the nuclei of AGNs and quasars Since 1994 there has been a steady growth in number of AO papers and the fraction of these that report scientific results 19

20 Cutting edge Science is being done with existing AO Systems The Science that has been accomplished with existing AO systems is significant: Imaging planets and their satellites at high resolution Imaging accretion disks; proto-planetary systems Discovery and imaging of very low mass stellar companions Measuring proper motions in the Galactic Center Resolving dense galactic and globular clusters Studying the stellar populations in nearby galaxies We will give some examples from just the last year alone 20

21 The Galactic Center A case study in the rapid progress that AO systems have made (Keck images courtesy of Andrea Ghez and collaborators unless otherwise noted) 21

22 AO Enables Discovery and Characterization of the Black Hole in the Center of the Galaxy: Diffraction limited imaging permits precise astrometry, proper motion, and radial velocity determinations of individual stars in the central few arc seconds The following discoveries have resulted: A central, supermassive black hole and direct determination of its mass via orbital dynamics Provides a unique laboratory for study of galactic nuclei Detection of IR emission from the black hole Very young massive stars orbiting within AU of the black hole Extended emission near the black hole 22

23 Three Generations of Diffraction Limited Observations of the Galactic Center 1. First generation: Speckle imaging (1995) Precise astrometry led to initial discovery of black hole Limitations: Complete only to K=15.5 because Strehl of only 0.05 to 0.1 No colors or spectra possible 2. Second generation: Natural Guide Star AO (2000) Permitted multi λ and spectral studies Further constrained properties of black hole Determine R 0 via spectroscopy of stars Detect L-band emission from Sgr A* Limitations: Needed excellent seeing because closest NGS is 30 distant and the GC is at large zenith angle even from Keck K band angular resolution still not at diffraction limit 23

24 Three Generations of Diffraction Limited Observations of the Galactic Center 3. Third generation: Laser guide star AO (2004) Dramatic improvement in quality of the observations Strehl ratio is typically 2 x higher than with NGSAO Achieve true diffraction limit in K band: shorter exposures more precise photometry, crowding problems reduced. Next generation could be an IR sensor for the tip-tilt: Would permit AO observations in very dusty, obscured regions in our galaxy and others - galactic nuclei and star forming regions Not new technology it is already in use on ESO-VLT! 24

25 80 x 80 Mosaic LGSAO Image of the Galactic Center Color composite of HeI-B (2.03 microns = blue) and Kcont (2.27 microns = red), observed with the NIRC2 wide camera (FOV=40x40 ) 25

26 The Galactic Center A comparison of natural guide star and laser guide star AO at L 5 G C LGS-AO 8 minutes SR=0.75 NGS-AO best ~160 minutes SR=0.34 Keck no AO, good seeing Stellar orbits around the central black hole that are measured via the precise astrometry enabled by AO give best estimate for its mass, 3.7(±0.2) 10 6 [R 0 /(8 kpc)] 3 M sun, and confine radius of the dark matter to <45 AU or a minimum density of M sun pc -3, 10 4 times greater than previous estimates (Ghez et al. 2005). 26

27 Precise photometry: LGSAO can extract Detailed Light Curve of Sgr A* from Crowded Region Sgr A* (Black Hole) 1 S0-17 (proper motion source) Discovery on Keck (Ghez et al.) and ESO VLT (Clénet et al. 2004a) of a variable 3.8 µm point source coincident with the Galaxy s central massive black hole and with Sgr A*. 27

28 The NIR/X-ray flare of Sgr A* at 2.18 µm First simultaneous detection of a near-ir/x-ray flare from the Sgr A* counterpart to the central black hole. The panels show images (ESO VLT in 2003 with FWHM of 60 mas) taken at different intervals of the measurements. The emission can be described by a SSC model in which the NIR and X-ray flux excess is produced by up-scattering submm photons into the NIR and X-ray domain. 28

29 Recent Scientific Results with Existing AO Systems: A Sampling 29

30 Solar System Studies The potential of diffraction limited imaging of solar system objects with the largest ground based facilities has been eagerly exploited by planetary astronomers: Spatial resolution in the near-ir is several times greater than with NICMOS on HST Spatially resolved near-ir spectroscopic studies enabled Observations in the thermal IR possible (not possible on HST) Imaging and spectroscopy in the near-ir and thermal IR are crucial for understanding planetary physics. Ease of access and ability to respond quickly 30

31 The Volcanoes of Io At 2.2 microns you see mainly reflected sunlight good agreement between Keck K band image and visible light Galileo image see next slide At 3.5 microns and longwards, thermal emission from the volcanic hotspots dominate. Observations of Io in eclipse reveal numerous faint hot spots that have too low a contrast to be visible on the sunlit images. Broad λ coverage allows temperature determinations over a wide range to accurately determine total heat flow from Io. 31

32 Io in the Sun: Near-IR (Keck), visible (Galileo) Note the close correspondence in albedo between the K and the visible light images. In the L band thermal emission from Io s volcanoes becomes very evident. Io is ~1.2 in diameter. The angular resolution of these images is mas at K and ~80 mas at L. (F. Marchis & I. de Pater: 32

33 Io in the Dark: Thermal IR Io as it appeared while passing through Jupiter s shadow. Its diameter was ~1.2. The angular resolution of these images is mas at K and ~80 mas at L. The deconvolution program MISTRAL used kernels of half these sizes. Note that the letters on the temperature frame do not correspond to those on the next slide. (de Pater et al. 2004) 33

34 Titan s Atmosphere and Surface Produced the highest resolution map of its whole surface (pre-cassini) Identified areas of high and low albedo perhaps corresponding to ice covered plains and basins of liquid hydrocarbons Discovery of clouds and of strong temporal and spatial changes in Titan s atmosphere that may be seasonal Determination of 3-dimensional atmospheric composition and structure 34

35 Discovery of Methane Clouds in Titan s Troposphere AO images obtained on Gemini and Keck in Narrow band filters probe Titan s upper troposphere while broad band K filters probe the lower troposphere and the surface (Roe, et al. 2002, ApJ, 581, 1399). 35

36 Titan with Keck and with Cassini at Saturn Map of surface of Titan at 1.6 µm with Keck AO between strong methane absorption bands. The resolution (small white circle in the upper right) is ~diffraction limit of Keck (0.04 or ~200 km on Titan). (H. G. Roe, et al., 2004, GeoRL, 31, L17). All of the main features visible on the Cassini map can be seen on Earth-based AO image with big telescopes. Agreement between several telescopes (Keck, VLT, Subaru) is excellent. CASSINI at Saturn 36

37 Titan: Keck AO and Cassini Note the close agreement between deconvolved AO image and the one from Cassini. 37

38 Uranus & Neptune: Atmosphere and Rings AO images from Keck achieve resolution of mas or better, several times greater than those with HST/NICMOS Near-IR spectroscopic studies yield 3-d information on atmospheric composition and dynamics Repeated near-ir observations allow study of the time evolution of their atmospheres, clouds, and rings. For example: The changing appearance of the Uranian rings reveals that the ring particles are distributed in a monolayer, in contrast to the many-particle thick layers seen in Saturn's rings (de Pater, et al. 2004). 38

39 Uranus the Power of AO Uranus and its rings with NIRC2 and AO on Keck with the AO system off and on. The rings are more easily seen at 2.2 µm because methane absorption at this λ makes the planet dark except for a few high altitude clouds. The first detection of bright clouds in Uranus Southern Hemisphere is indicative of the start of vigorous convective activity as this region cools for the first time in a Uranian year 39

40 Uranus with HST and Keck AO HST, Visible Keck AO, IR Keck AO is a composite at 1.26, 1.62, and 2.1 µm (L. Sromovsky). The highest clouds appear white, the middle level ones bright green, the lower ones a darker blue. This color balance makes the rings appear red. Higher clouds are most abundant in the north. Lesson: Keck in near IR has same resolution as Hubble in visible 40

41 AO Enables Synoptic Observations of the Atmospheres and Rings of Uranus and Neptune Neptune s atmosphere is rich in dynamic features such as vortices, waves and narrowly spaced bands of clouds similar to those present around Jupiter. Spectroscopic observations with AO enable 3-d determination of atmospheric structure of Neptune and Uranus Images a and b were taken on successive days in 2002 on Keck (Gibbard et al. 2003). Uranus' ring system at 2.2 µm (AO on Keck on 3-9 July 2004). The individual rings are clearly recognized, as well as a sheet of material interior to rings 4,5, & 6. This is the first image since the Voyager encounter in 1986 that reveals this broad faint dusty ring. (I. de Pater, S. Gibbard, H. Hammel) Neptune at H Keck AO (a & b) and HST/NICMOS (c) ~2 arc sec c 41

42 Stellar Astrophysics: Disks and Companions 42

43 Disks around stars Can now move beyond merely discovering circumstellar disks to studying their structure and physical characteristics. Examples: AU Microscopii a 12 Myr old M dwarf with disk: overall morphology of disk points to the influence of unseen larger bodies and resembles structures expected from recent or ongoing planet formation. Thermal IR: Adaptive secondary on MMT achieves Strehl of 0.97 with 0.1 resolution at 9.8 µm and resolves disk around an AGB star RV Boo via its thermal dust emission M ~ 1.6 x 10-6 M sun (Biller, et al. 2005). 43

44 AO Enables the study of the structure and physical properties of circumstellar disks. Orbit of Neptune AU Microscopii an edge on disk revealed AU Microscopii dust disk at 1.6µm observed on Keck, FWHM = 40 mas. Substructure indicated by A, B, and C in the figure is evidence for both a limb brightened ring a step on the road to planet formation and a gap in the disk which could be due to a planet orbiting in the disk. 44

45 A Rare Example Perrin & Graham 2005 HAeBe A2/A5 binary V = 12.8 mag natural guide star Both stars have disks only the edge-on one is revealed by conventional AO Wing-nut structure is likely the first time a disk wind driven by the central star has been imaged 45

46 Spiral Structure in the AB Aur Disk H-band coronagraphic image with AO on Subaru reveals spiral structure in the disk of AB Aur. A reference PSF was subtracted. The linear, radial features are due to Subaru s spider. The field of view is 8 x 8.0 Star s age is only 4 Myr suggesting that the structure is maintained for ~106 yr, much longer than the dynamical timescale of 10 4 yr at r ~ 400 AU (Fukagawa, et al. 2004). 46

47 Binary Stars AO systems enable highly precise astrometry (via imaging) and radial velocities (via near-ir spectroscopy) of close binaries Orbital parameters and masses can be determined on short time scales. Empirically determined physical parameters (mass, luminosity, temperature, radius) can be used to calibrate stellar models, especially for low mass stars and planetary like companions. Processes in the formation and evolution of low mass stars can be elucidated 47

48 Binary Stars Examples of Results Osorio et al. (2004): high resolution near-ir spectra on Keck establishes GJ 569Bb as the first genuine brown dwarf known without requiring any theoretical assumptions. Beuzit, et al. (2004) with AO on the CFHT identify 21 new components in binary systems in the solar neighborhood. It will be possible to determine accurate masses for many of these stars. Close et al. (2004) used the AO camera on VLT discover a young (50 Myr) companion to AB Dor A - AB Dor C - and determine its mass (0.090 ±0.005 Msun) and find that masses of such objects have been underestimated frequency of brown dwarfs and planetary mass objects in young clusters has been overestimated. 48

49 Discovery of AB Dor C on the VLT Discovery image of AB Dor C with the NACO SDI (Simultaneous Differential Imager) high contrast camera on VLT. Top: At µm image. Bottom: The SDI of the µm images revealing the significantly redder source AB Dor C. AB Dor C is the faintest companion ever imaged within 0.16 of a star (white scale bar; Close et al. 2004). 49

50 AO Enables Search and Discovery of Faint Companions to Stars: The first image of an exo-planet? Composite image of brown dwarf 2M1207 and its faint red companion in H (blue), Ks (green) and L (red). (Chauvin et al. 2004, ESO NAOS AO System on VLT with IR wavefront sensing). Estimated mass of companion is 5 ± 2 M Jupiter at ~55 AU from the brown dwarf (Pluto is at 40 AU from Sun) 50

51 Extragalactic Astrophysics with AO 51

52 AO Enables Study of Galaxies with Near-IR Resolution 3-4 x that of HST 1 arc sec = 470 pc Star-forming clusters 1.4 arc sec 1.8 C. Max kev Komossa CHANDRA: High energy x-rays from region near black holes P. Schneider Hubble, NICMOS, 2.2 µm Keck AO: NIRC2, 2.2 µm Nearby AGN NGC 6240: A disk galaxy merger and a starburst galaxy with two black holes in its nuclear region as shown by Chandra. Diffraction limited near-ir image with Keck reveals structure in the two nuclei along with intense star forming activity. 52

53 Laser Guide Stars Dramatically Extend AO s Reach for Extragalactic Research High galactic latitude fields have a paucity of natural guide stars LGS AO systems are now routinely available at Keck and Lick, and soon at Gemini N and S, VLT, Subaru, Palomar, MMT AGN XID-56 in GOODS-South, imaged by HST (BViz), Keck LGS AO (K ), and VLT ISAAC (Ks). This AGN has an optical-ir jet, as well as point-like substructure suggestive of a merger. The jet appears to point to the compact feature to the SW of the main nucleus. The Keck LGS image has spatial resolution comparable to HST at B and V, and superior to HST at i and z bands. Importance of HST + Keck: Combination of HST B-V-i-z with Keck LGS K constrains the dominant stellar population in the AGN s core to be young and dusty (age ~50 Myr, dust τ ~5). HST data alone does not distinguish between a population that is 300 Myr old and dust-free and one that is 50 My old and dusty (Melbourne, et al. 2005). 53

54 NGC 1068 Coronography combined with AO Combination of a coronagraph and an AO system is able to mask the bright core of NGC1068 and reveal the complex structure that exists in the circum-nuclear region. Top: NGC 1068, Ks band with NACO on ESO VLT without mask. Bottom: reference subtracted coronographic image (Gratadour, et al. 2005). 54

55 QSO and AGN results that relied on AO Diffraction limited K-band spectroscopy reveals that massive star formation in the nuclear region of the QSO PG can account for most of the far-ir emission from this quasar (Cresci et al on ESO VLT). Non-detections of host galaxies around z~2 QSOs which are ~50 brighter than local QSOs and AGNs => either fueling efficiency is much greater at high z or central black holes are much more massive (Croom et al on Gemini). 55

56 The Next Step 56

57 Science on a GSMT with AO: The New Generation of Large Telescopes GSMT with AO: the Decadal Survey s highest ranked ground based major initiative. Science on a GSMT will be dramatic and far-reaching. Its key science programs answer fundamental questions that range in scale from the structure and evolution of the Universe to the formation of Earth-like planets and conditions necessary for the appearance of life A GSMT addresses four of the Eleven Science Questions for the New Century : What is Dark Matter? Study of weak lensing and the dynamics of distant galaxies and clusters What is the Nature of Dark Energy? Study the accelerating universe with distant supernovae How did the Universe Begin? Determine large scale structure of the very early Universe How Were the Elements from Iron to Uranium Made? Spectroscopic analysis of faint, old stars in different environments With development of extreme AO (ExAO) systems, a GSMT will play a leading role in the search for and study of planets around other stars. It will be a strong complement to NASA s TPF mission. 57

58 AO is Necessary to Enable all Extremely Large Telescopes (>20-30 m) Reach Their Full Potential Compensate for atmosphere induced image distortions Reach diffraction limited resolution of full telescope aperture for λ > 1 µm 8 mas at 1.0 µm for a 30-meter primary mirror 1 AU at 150 pcs (nearest star-forming region) 50 pcs at z=3 detailed studies of young star forming galaxies Reduce background noise by orders of magnitude for point source detection and for spectroscopy Time to achieve a fixed signal/noise ~ (image size) 4 ~ 1/D 4 Significantly reduce the physical size of instruments Development of multi-beacon laser tomographic systems required for full sky coverage, even for narrow field AO Single beacon on m telescope suffers severely from the cone effect : the laser guide star is at a finite altitude and thus provides an incomplete sample of the atmosphere in the telescope beam. Tomography + multiple deformable mirrors will allow for full 3-d correction of atmospheric turbulence over a wide field of view (MCAO) Very high order correction to enable AO in the visible 58

59 Concepts for AO on future m telescopes 59

60 Laser guide star AO today 90 km This missing data results in the cone effect, namely the data needed to correct the wavefront is best available in the cone from the LGS to the primary mirror. The greater the distance from the LGS to the field center, the less optimum is the correction. The larger the primary mirror, the worse the effect is. Multiple LGS each with its own wavefront sensor works to optimize the correction in the center of the field, but to increase the actual FOV, you also need multiple deformable mirrors, each one sampling a different height in the atmosphere. Missing Data 60

61 Tomographic (MCAO) AO 90 km MMT is beinning testing of multiple beacon laser system; Gemini South MCAO system will begin tests in

62 Europeans are moving ahead with MCAO systems Ragazzoni et al, 2000: Collected optical data on a constellation of 4 stars Used outer 3 stars to predict phase errors for the central star Atmospheric phase error estimates superior to classical AO MCAO will work! 62

63 Current vs. future AO architectures Today: Single conjugate AO 1 deformable mirror (DM) 100s of degrees of freedom Limited field of view (~40") One laser guide star : Multiconjugate AO (MMT, Gemini) 3 deformable mirrors Wider field of view (arc mins) Multiple laser guide stars : Advanced AO on 8-10m class telescopes ExAO and/or GLAO (Gemini, MMT, VLT) KPAO (Keck) ExAO and/or GLAO (VLT) m telescopes will have Tomographic AO multiple LGSs Single conjugate, narrow field, all sky Multiple AO systems, most with multiple laser guidestars Multi-conjugate AO Multi-object AO Ground layer AO Mid-infrared AO (possibly NGS) Extreme AO for planet detection Very high order DMs and wavefront sensors to reach visible ~3000 actuators/subapertures to scale up existing AO systems ~11000 actuators/subapertures for enhanced performance 63

64 One Possible Approach to AO on ELTs Phase 0: AO with existing or very near-term components (why we could use a GSMT now!) on a ELT: ~ 30 2 deformable mirrors and wavefront sensors 50W class sodium lasers for minimum 3 beacons AO Performance in K similar to existing 8-10 meter systems in H Phase I: Match AO performance of current systems on 8 to 10 meter class telescopes (baseline) ~ 60 2 deformable mirrors scaled from existing technology Radial CCD arrays (now funded by AODP!) &50W class sodium lasers IR tip/tilt sensors to enhance sky coverage (ESO now has operating system) Phase II: Enhanced performance for advanced applications including ExAO ~ mirrors and sensors MEMS mirrors, adaptive secondary mirrors, and lasers with high power and/or specialized pulse formats LGS AO Performance at 1 µm similar to current systems in H Enables full potential of a GSMT for exoplanet detection 64

65 Phase 0: AO with Existing Components Natural guide star (NGS) AO Utilize an existing 35 2 deformable mirror with a actuator bimorph for low-order, large stroke correction Utilize existing pixel CCD arrays from MIT/LL or E2V Laser guide star (LGS) AO Multiple guide stars required due to the cone effect Guidestar elongation requires higher laser power, improved wavefront sensor (WFS) sampling of the guidestar image Nearest term approach: 3 17-Watt beacons produced by one existing 50-Watt Starfire Laser 30 2 WFS subapertures of 8 2 pixels each on next generation Fairchild or E2V CCD arrays 65

66 Phase I: Scaling 8-10m MCAO to 30m Objective is near-diffraction limited performance in J, H, K on a 2 FOV Component Deformable mirror at h=0 km Deformable mirror at h=10 km Guidestar laser Laser guide star WFS detectors Natural guide star tip/tilt sensor infra-red detectors (option for improved sky coverage) Requirement 63 2 actuators ~5 mm spacing 7-8 µm stroke 39 2 actuators ~10 mm spacing 4-5 µm stroke 5-7 guidestars produced with 2 50-Watt laser systems Radial format CCD, visible wave front sensing 45k-181k pixels Hz, 3-5 electrons pixels Hz 1-3 electrons Technical Readiness 41 2 actuators 4.5 mm spacing 7-8 µm stroke (fixed-price contract for the ESO Planet Finder DM) 39 2 actuators 7 or 9 mm spacing ~4 µm stroke (Existing USAF mirrors produced by Xinetics) 50 W CW sodium laser (USAF Starfire Optical Range system) AODP contract with MIT/LL to develop prototype (at risk if AODP is cancelled) Prototype amplifier designs produced by Rockwell (tests planned) 66

67 Notional Phase I MCAO Error Budget Term Turbulence compensation Fitting error Tomography / Aniso. Servo Lag LGS WFS noise AO implementation Uncorrectable Telescope Uncorrectable Instrument Total Error, RMS nm Requirement/Comments RSS of below 0.5 m actuator pitch 5 LGS 25 Hz -3dB bandwidth σ θ =0.1 arc sec at 800 Hz ~17W/LGS at 0.5m (feasible) Allocation Allocation Allocation RSS of above 67

68 MCAO Performance vs. Number of DMs (Atmospheric Error Terms Only) MCAO performance with 6 LGS s and 1 (black), 2 (blue), and 3 (red) DM s 1 DM 2 DMs 3 DMs 0.6 Strehl ratio I band J band H band K band FOV offset, arc min 68

69 Phase 2: MCAO with High Strehl at 1 µm R&D investment Needed Needed Order ~120 2 wavefront correction Stacked PZT with 2.5 mm spacing MEMS alternative ~2 mm stroke Separate woofer for large-stroke, low order correction Order wavefront sensing Radial CCD geometry 180k to 720k pixels Hz, 3-5 electrons Increased Laser Power/sophistication 70 W/beacon with CW lasers W/beacon with short pulses tracked through the sodium layer Today DM prototypes in development 42 2 PZTs with 2.5 mm spacing, 2.5 µm stroke 32 2 MEMS with 1-2 µm stroke Adaptive secondaries with D= m and ~ modes WFS CCDs in Development Radial format CCD at MIT/LL (AODP) 64k pixel Fairchild and E2Varrays Lasers in Development Starfire 50W CW laser CIT and LLNL short pulse laser R & D (AODP) 69

70 Advanced Component Technologies Support Additional AO Modes Multi-Object AO (MOAO) MEMS with actuators, 4-5 µm stroke, high repeatability (Laser and WFS requirements are similar to MCAO at 1 µm) ExAO WFS CCDs with k pixels, 2500 Hz, 3-5 electrons (Near IR preferred) (DM requirements are similar to MCAO at 1 µm) Mid IR AO Low-emmisivity DM with modes (cooled, cryogenic, or an adaptive secondary mirror) All modes benefit from an adaptive secondary mirror Relaxes stroke requirements No additional surfaces or increase in emissivity 70

71 Details of Deformable mirror requirements: a few years of R&D investment is needed Today Stacked PZT with glass face sheet Stroke a few µm Actuator pitch ~ 11 mm Diameter a few inches degrees of freedom MEMS technology alternative 1000 degrees of freedom 2.5 micron stroke Adaptive Secondaries Diameter 0.6 meter 336 degrees of freedom Stroke µm Future: Needed Stacked PZT Longer ( 10 µm), smaller pitch ~3-5 mm Diameter ~ 30 cm O(10 4 ) D of F Scalable from present but expensive MEMS technology alternative Higher stroke ( 10 microns) Actuator pitch ~ 600 microns Diameter ~ 6 cm O(10 4 ) degrees of freedom >smaller >cheaper than PZTs, greater risk? Adaptive Secondaries Diameter up to 3.5 meters May be segmented 1000 degrees of freedom (mid-ir) Stroke µm A known technology Cryo DMs for mid-ir AO 71

72 MEMS are a key enabling technology MOAO requires DMs MEMS are significantly less expensive per actuator than conventional DMs Mass-produced once the process and mask are developed Field replaceable Allows the whole AO optical system to be much smaller Saves money, space Enables multi-object AO, Extreme AO Higher risk, higher payoff Investment is needed! MOAO concept using MEMS: Dedicated AO for each galaxy 72

73 MEMS 1000 actuator DM, Laboratory for AO at UCSC 73

74 Details of Laser requirements (λ = 589 nm): Pulsed laser development probably needed Today Watts (Lick & Keck) 50 Watts, Na (USAF - SOR) Excellent beam quality Relatively inexpensive (~$2M) Effectively CW Conventional optics for beam projection Watts Future: Needed Pulsed with specific format for pulse-tracking through sodium layer and to avoid fratricide from Rayleigh scatter Can get by with CW format if power is higher Fiber optics for beam projection Solutions exist now need to choose best option 74

75 Details of Wavefront sensing requirements: some development needed Today Fast low-noise CCDs (visible) Moderate-noise fast IR detectors (50 e-) Single wavefront sensor for narrow field of view AO 16 Kpixels, 500 Hz frame-rate Future: Needed CCDs that can track laser pulse as it transits sodium layer Work underway now at Lincoln Labs funded by AODP. Work is at risk if AODP cut/eliminated Low-noise fast IR detectors (2 e-) Multiple wavefront sensors for tomographic sensing Kpixels, 500 Hz framerate Modeling the AO systems is hard but it is being done now successfully. Ability to predict performance from designs of new systems and ability to actually run them should happen next year. The path is straightforward. 75

76 Planned evolution from current AO systems to future giant telescopes Planned evolution of current AO systems Laser systems at Keck, Gemini N and S Multiple laser beacon systems at MMT, Gemini South Deformable secondaries at UA (MMT, LBT) ExAO system at Gemini or Keck GLAO wide-field and/or <1µ systems Proof of concept for additional new systems, e.g. Multi-object AO using a MEMS for each high-z galaxy Ground layer AO for wide field of view at modest resolution Continued NSF investment in AO development: Deformable mirrors (conventional, MEMS, adaptive secondaries) Pulsed lasers Low-noise large-format wavefront sensor detectors Build on results from NSF Center for AO at UCSC and from CAAO at UA Complement to work being done in Europe ESO, Euro-50, series of Research and Training Networks funded by EU 76

77 Our European colleagues are moving ahead aggressively VLT already has infrared wavefront sensor for tip-tilt VLT MCAO program will exploring alternative approaches, e.g. layer-oriented vs. tomographic techniques ExAO and GLAO under serious consideration for secondgeneration VLT instruments European network (OPTICON) established to coordinate and enhance European institutions AO modeling and simulation capabilities funding post-docs at between FTE s/year ESO funding at least two parallel Na laser technology studies (e.g. fiber lasers) 100m OWL is a highly effective coordinating force behind European AO efforts 77

78 Conclusions AO correction of a GSMT is possible with today s technology but Would be most effective in the mid-ir; only low resolution correction at K band sky coverage similar to current AO systems. Correction of faint objects will be possible with multiple laser beacons To correct even a narrow field, proposed multiple beacon tomography methods will be needed Testing and implementation of such systems are underway Exo-Planet imaging potential high for GSMT given further AO development (an Extreme AO system, ExAO) AO developmental work has already greatly enhanced the capabilities of existing telescopes to do cutting-edge science. 78

79 The Role of Adaptive Optics and the AODP in the Future of US Ground Based Astronomy 79

80 Adaptive Optics: The New Frontier of Ground Based Astronomy Already 8m-10m AO-enabled telescopes are achieving unprecedented improvements in angular resolution and sensitivity At near-infrared wavelengths, ground-based telescopes regularly deliver comparable angular resolution to HST in the optical Evolutionary enhancements of current technologies for 20-30m telescopes will ensure near-ir Strehls comparable to today's 8m-10m ones Need improved deformable mirrors, lasers, wavefront sensors. Not fundmental departures. Diffraction limited spatial resolutions will by 3-5 times better than JWST s at the same wavelength In addition adaptive optics is on the verge of several revolutionary developments that will also be scientifically revolutionary Multi-conjugate, 3-d tomography (MCAO) will enable diffraction limited imaging over a field of view ~10 x greater than single-conjugate AO many arc minutes. Multi-object AO enabled by MEMS: tiny deployable AO system under every galaxy Extreme-AO, capable of characterizing solar systems like our own at the distance of the closest star forming regions Ground Layer Adaptive Optics (GLAO), delivering wide-field compensated images to probe large volumes of the high red-shift Universe (First-Light objects) NSF, as the Federal Agency with the sole responsibility for the US groundbased astronomy program, has a unique opportunity to enable such breakthroughs through its support of the AODP 80

81 Roles of TMT, GMT, CfAO, CAAO Role of TMT Project: Focused on completing "cost proposal" in 2 years Lower-risk evolutionary, but credible approach to component development for 30m scale adaptive optics TMT AO funding areas in next 2 years: Designs for five specific AO systems Evolutionary improvements in deformable mirrors: piezo-stack mirrors, face sheets for adaptive secondaries Modest ($200K) investment in MEMS deformable mirrors; improved IR sensors Subscale lab and field tests of system concepts Role of GMT Project in next 2 years: Gregorian deformable mirror development, building on LBT experience Extreme AO design and lab tests based on focal plane interferometry Closed loop multi-beacon tomography AO at the MMT Roles of CfAO and CAAO: Have fostered important new system concepts for AO, have created and trained a new AO science user community Both are funding research on new system and component concepts, and on tests and implementations at existing telescopes But cost of full-up development of the most innovative and revolutionary approaches to AO at the scale needed for GSMT is beyond the capabilities of the centers and the two projects 81

82 AODP's role is key to the future vitality of the US Ground-Based Program in Astronomy Existing organizations (TMT Project, GMT Project, CfAO, CAAO, Gemini) are researching new concepts and sub-gsmt-scale implementations Gemini, Keck, MMT are enabling systems at the 6m-10m scale TMT is paying for evolutionary improvements in piezo-stack deformable mirrors, adaptive secondaries, IR sensors but on a two year horizon. AODP funding is crucial for R&D on higher-risk, higher-payoff approaches with potential for large impact on 20-30m telescope science goals MEMS and other advanced deformable mirrors Pulsed lasers that reduce laser spot elongation, fratricide New tomography approaches and system tests Optimized wavefront sensors and tip-tilt sensors AODP time horizon can uniquely focus on strategic investments which have the potential to revolutionize both current and future ground-based facilities. Continued, stable AODP funding will have huge long-term scientific benefits. NSF excels at these types of investments 82

83 BUT 83

84 NSF has drastically cut funds for the recently begun Adaptive Optics Development Program AO top moderate initiative in 1990 Decadal Survey and strongly endorsed in 2000 Survey AO Roadmap 2000 Workshop concluded: New and sustained investment in AO systems is essential Key components have long development lead times Commercialization requires long-term investment Investment in AO which is essential for extremely large telescopes will greatly benefit existing telescopes 6 out of 17 proposals chosen for funding in 2003: 2 high power Na laser development programs 2 large format, low noise detectors for optical wavefront sensors 1 high actuator count macro-deformable mirror 1 study to develop advanced wavefront reconstruction algorithms All but one funded proposal are multi-year efforts 84

85 Recommended for Funding in 2004 The following programs were recommended for funding in 2004 June in the second competitive round for NSF s AODP Program but now cannot be funded Concept validation of GLAO and MCAO with Multiple Laser Beacons at the MMT Development of a Pathfinder for ELT Adaptive Secondaries 256 x 256 Split Frame Transfer CCD/CMOS Hybrid Wavefront Sensor Silicon Micro-machined Deformable Mirror Technology for Advanced Astronomical Optics Applications Sparse Optimal Adaptive Real-time Construction (SOARTR) New approach to modular, scalable, fiber laser guide stars 85

86 Under Present Guidelines NOAO will continue to monitor 2003 AODP awards If any fail to meet their milestones, one of the six selected 2004 programs can be commenced New funding in 2007 or sooner is an important complement to GSMT design and development Because the 2004 AODP selected projects test prototype systems on existing telescopes, they would greatly add to the capabilities of these telescopes 86

87 Findings and Recommendation Cuts to and planned elimination of the NSF AODP will bring much of the new development work on AO for public and private US observatories to a halt. AO must be integrated into the Giant Segmented Mirror Telescope design from the start. Thus, cuts to AODP will have an immediate negative impact on the design and development of a GSMT. The rapid advances being made with AO systems on existing telescopes will come to a near standstill as will the exciting science that has resulted from these advances. NSF should restore Adaptive Optics Development Program funding! 87