Exoplanet Imaging with the PIAA Coronagraph: Latest Laboratory Results from NASA Ames Rus Belikov, Michael Connelley, Tom Greene, Dana Lynch, Mark McKelvey, Eugene Pluzhnik, Fred Witteborn (NASA Ames Research Center) Olivier Guyon (Subaru / UofA) Outline Motivation for PIAA and overview Lab description and results New PIAA mirror manufacture and simulations Shanghai, July 23, 2009

PIAA (phase-induced amplitude apodization) overview and motivation 2 PIAA invented by Olivier Guyon with significant contributions by Bob Vanderbei, Wesley Traub PIAA invented by Olivier Guyon with significant contributions by Bob Vanderbei, Wesley Traub High-throughput (almost 100%) High-throughput (almost 100%) Aggressive IWA (2 /D) Aggressive IWA (2 /D) Potentially enables Earth-like planet imaging with a 1.4m telescope (PECO) Potentially enables Earth-like planet imaging with a 1.4m telescope (PECO) Can also be used on a balloon (planetscope) or TPF Flagship Can also be used on a balloon (planetscope) or TPF Flagship Track record of successful hardware development and testing Track record of successful hardware development and testing Focal plane Original uniformly illuminated pupil plane New, apodized pupil plane Focal plane PECO mission concept Simulated Earth image around Tau Ceti, Shaped pupil Apodizer

ARC testbed description and role in PIAA technology development 3 New (March 08), flexible, rapidly reconfigurable facility in air New (March 08), flexible, rapidly reconfigurable facility in air Successor to Olivier Guyon’s 1 st PIAA testbed at Subaru Successor to Olivier Guyon’s 1 st PIAA testbed at Subaru Dedicated to testing PIAA and related technologies Dedicated to testing PIAA and related technologies Partnering with JPL’s HCIT, with complementary roles identified Partnering with JPL’s HCIT, with complementary roles identified ARC ARC initial validation of lower TRL technologies and concepts initial validation of lower TRL technologies and concepts MEMS DMs MEMS DMs WFC architecture trades WFC architecture trades dichroics dichroics PIAAgen2 mirror manufacture PIAAgen2 mirror manufacture JPL/HCIT JPL/HCIT higher TRL and vacuum validation higher TRL and vacuum validation testing a variety of coronagraphs testing a variety of coronagraphs Ames Coronagraph Lab In a partnership with JPL’s HCIT

Other partnerships and roles 4 NASA Ames Research Center Tom GreeneARC testbed director Mark McKelveyARC testbed manager Rus Belikovtechnical lead Eugene Pluzhnikexperiments Michael Connelleyexperiments Fred Wittebornthermal enclosure Dana Lynchoptical design Tinsley Laboratories (PIAA mirror manufacture) Daniel Jay Asfaw Bekele Lee Dettmann Bridget Peters Titus Roff Clay Sylvester NASA Jet Propulsion Lab John Trauger Andy Kuhnert Brian Kern Marie Levine Wesley Traub Stuart Shaklan Amir Give'on Laurent Pueyo UCSC (DM characterization) Donald Gavel Daren Dillon Renate Kupke Andrew Norton UofA/Subaru (PIAA design and consulting) Olivier Guyon Lockheed Martin (Optical design) Rick Kendrick Rob Sigler Alice Palmer

First stage of experiments 5 Initial goal: create a testbed capable of supporting high contrast levels (1e-9) Initial goal: create a testbed capable of supporting high contrast levels (1e-9) Approach: keep things as simple as possible Approach: keep things as simple as possible Use lenses Use lenses Use monochromatic light Use monochromatic light Switch to mirrors and broadband light once testbed stability and wavefront control are developed to better than ~1e-8 contrast Switch to mirrors and broadband light once testbed stability and wavefront control are developed to better than ~1e-8 contrast (Or maybe lenses can be made sufficiently achromatic and with a good enough AR coating?) (Or maybe lenses can be made sufficiently achromatic and with a good enough AR coating?) Light source (single mode fiber-coupled laser) 650nm DM (deformable mirror) CCD PIAA System Focusing lens Collimating lens Focal plane occulter Lens

PIAA system Light source (single mode fiber-coupled laser) 650nm DM (deformable mirror) CCD PIAA System Focusing lens Collimating lens Focal plane occulter Lens Made by Axsys, diamond-turned CF2, 16mm active diameter Made by Axsys, diamond-turned CF2, 16mm active diameter Post-apodizer (concentric-ring shaped pupil) made by JPL’s Microdevices laboratory, aluminum on glass Post-apodizer (concentric-ring shaped pupil) made by JPL’s Microdevices laboratory, aluminum on glass

7 MEMS Deformable Mirror Light source (single mode fiber-coupled laser) 650nm DM (deformable mirror) CCD PIAA System Focusing lens Collimating lens Focal plane occulter Lens Made by Boston Micromachines, 32x32 actuators, 10mm active area Made by Boston Micromachines, 32x32 actuators, 10mm active area Strong motivation for small MEMS DMs: for small telescopes, small DM size may be necessary to keep instrument size reasonable Strong motivation for small MEMS DMs: for small telescopes, small DM size may be necessary to keep instrument size reasonable

Contrast results Wavefront control algorithms (both based on image-plane sensing through DM diversity): Variant of classical speckle nulling (Trauger and Burrows) Based on targeting and removing individual speckles Many speckles at a time For each speckle, scan not only the phase, but also the amplitude of corresponding ripples on DM Slow (100s of iterations, hours), but does not require detailed system model Electric Field Conjugation (Give’on et. al.) Estimates and corrects the entire dark zone on each iteration Fast (minutes), but requires a precise system model 1.5e-7 from 2.0 to 4.8 /D

Stability 9 ~10-20mK rms temperature variation over 20 minutes 3e-9 - 1e-8 rms speckle variation over 20 minutes

Active thermal control system Water circuit with PID controller Water circuit with PID controller An earlier version already demonstrated by Guyon at Subaru An earlier version already demonstrated by Guyon at Subaru Expected to provide a few mK-level temperature stability or better and stability of better than 1e-9 Expected to provide a few mK-level temperature stability or better and stability of better than 1e-9 10

Limiting factors Major limiting factors in the past: Major limiting factors in the past: CCD artifacts (scattering off microlenses, CCD circuitry and shutter) CCD artifacts (scattering off microlenses, CCD circuitry and shutter) Eliminated by introducing a focal plane stop Eliminated by introducing a focal plane stop Ghosts from transmissive elements Ghosts from transmissive elements Eliminated by a long-coherence-length laser Eliminated by a long-coherence-length laser Alignment, baffling, system model, air currents Alignment, baffling, system model, air currents Current known limiting factors Current known limiting factors Polarization effects Polarization effects Starting to control with polarizers Starting to control with polarizers Expected future limiting factors Expected future limiting factors Stability (1e-8) Stability (1e-8) DM voltage level quantization (1e-9 to 1e-8) DM voltage level quantization (1e-9 to 1e-8) Solving limiting factors seems to proceed at a predictable rate (2x improvement in contrast every 6 weeks), as long as funding persists Solving limiting factors seems to proceed at a predictable rate (2x improvement in contrast every 6 weeks), as long as funding persists 11

12 By Sydney Harris

New PIAA mirrors manufactured Made by Tinsley Made by Tinsley Gen2: Better achromatic design, better surface accuracy than gen1 mirrors Gen2: Better achromatic design, better surface accuracy than gen1 mirrors Currently being tested at HCIT Currently being tested at HCIT

14 Wavefront quality Surface figure spec was only for spatial frequencies < 20 cycles per aperture Surface figure spec was only for spatial frequencies < 20 cycles per aperture That left mid-spatial frequency errors high That left mid-spatial frequency errors high We now know though simulations that these errors can hurt us We now know though simulations that these errors can hurt us

Modeling of gen2 mirrors 15 Fast but approximate model confirmed by higher fidelity ones (Amir Give’on and Laurent Pueyo) Fast but approximate model confirmed by higher fidelity ones (Amir Give’on and Laurent Pueyo) Predicts that current Tinsley mirrors will get to no better than 1e-9 Predicts that current Tinsley mirrors will get to no better than 1e-9 Limited by chromaticity of frequency folding of mid-spatial frequency errors Limited by chromaticity of frequency folding of mid-spatial frequency errors Different WFC architectures don’t help much Different WFC architectures don’t help much Mirrors can be smoothed by a factor of 2, bringing theoretically possible contrast to 1e-10 Mirrors can be smoothed by a factor of 2, bringing theoretically possible contrast to 1e-10 Modeling of PIAA is mature, but accuracy of fast approximate models not well quantified Modeling of PIAA is mature, but accuracy of fast approximate models not well quantified

Conclusions 16 New laboratory at NASA Ames was established for prototyping PIAA coronagraph and related technologies through early TRL levels before vacuum testing at JPL’s HCIT New laboratory at NASA Ames was established for prototyping PIAA coronagraph and related technologies through early TRL levels before vacuum testing at JPL’s HCIT State of the art coronagraph performance at 2 /D : 1.5e-7 State of the art coronagraph performance at 2 /D : 1.5e-7 Vacuum testbeds may not be required to work in high contrasts (~1e-9) Vacuum testbeds may not be required to work in high contrasts (~1e-9) A new PIAA coronagraph mirror set manufactured (by Tinsley) designed for 1e-9 contrast in a 10% band A new PIAA coronagraph mirror set manufactured (by Tinsley) designed for 1e-9 contrast in a 10% band