HC(ST) 2 : The High Contrast Spectroscopy Testbed for Segmented Telescopes

Transcription

1 HC(ST) 2 : The High Contrast Spectroscopy Testbed for Segmented Telescopes Garreth Ruane Exoplanet Technology Lab, Caltech NSF Astronomy and Astrophysics Postdoctoral Fellow On behalf of our Caltech/JPL team: D. Mawet, J.R. Delorme, D. Echeverri, J. Fucik, N. Jovanovic, J. Llop Sayson, M. Zhang, A.J. Riggs (JPL), E. Serabyn (JPL), S. Shaklan (JPL), J.K. Wallace (JPL) 2018 California Institute of Technology. All Rights Reserved. Government Sponsorship Acknowledged.

2 Exoplanet Technology (ET) lab at Caltech 2 Goal: To enable the direct detection and spectral characterization of exoplanets from the realm of gas giants to rocky planets in the habitable zone.

3 Exoplanet Technology (ET) lab at Caltech PI: Prof. Dimitri Mawet 3 The High Contrast Spectroscopy Testbeds for Segmented Telescopes HCST-T HCST-R See posters: Jorge Llop Sayson (Thursday) Yinzi Xin (Thursday) See posters: Nemanja Jovanavic (Monday) Manxuan Zhang (Tuesday) Daniel Echeverri (Wednesday)

4 Exoplanet Technology (ET) lab at Caltech Poster by Jorge Llop Sayson on Thursday evening Electric Field Conjugation with a Single Mode Fiber Finds the shape of the deformable mirror (DM) that minimizes the overlap integral of the electric field with the fundamental mode of the fiber. Jorge Llop Sayson 4 Simulations Laboratory experiments

5 Exoplanet Technology (ET) lab at Caltech Poster by Jorge Llop Sayson on Thursday evening Electric Field Conjugation with a Single Mode Fiber Finds the shape of the deformable mirror (DM) that minimizes the overlap integral of the electric field with the fundamental mode of the fiber. Jorge Llop Sayson 5 Simulations Laboratory experiments

6 Exoplanet Technology (ET) lab at Caltech 6 Poster by Yeyuan (Yinzi) Xin on Thursday evening Speckle Nulling on a Single-Mode Fiber with a Kalman Filter A Kalman filter uses measurements and control history to find best estimate of speckle nulling parameters (amplitude and phase). 10% improvement using Kalman filter rather than single measurements alone. Start with speckle Speckle is suppressed

7 Exoplanet Technology (ET) lab at Caltech 7 Poster by Yeyuan (Yinzi) Xin on Thursday evening Speckle Nulling on a Single-Mode Fiber with a Kalman Filter A Kalman filter uses measurements and control history to find best estimate of speckle nulling parameters (amplitude and phase). 10% improvement using Kalman filter rather than single measurements alone. Start with speckle Speckle is suppressed

8 HCST: a proving ground for exoplanet detection and characterization methods 8 Apodizer Lyot stop Focal plane mask Source Segmented DM Mask Coronagraph Telescope simulator Jupiter Earth Reflectance spectra Cite: J-R. Delorme et al. (2017) See posters: Nemanja Jovanovic Simulated image High resolution spectrograph

9 HCST: a proving ground for exoplanet detection and characterization methods 9 Apodizer Lyot stop Focal plane mask Source Segmented DM Mask Coronagraph Telescope simulator Jupiter Earth Reflectance spectra Cite: J-R. Delorme et al. (2017) See posters: Nemanja Jovanovic Talk by Ji Wang Thursday 11:10 AM Simulated image High resolution spectrograph

10 Apodized vortex coronagraphs for segmented telescopes 10 Telescope pupil Apodizer design Raw contrast Coronagraph design: Ruane et al. (2016) Jewell et al. (2017) Ruane et al. (2018) Supported by NASA ExEP SCDA study

11 Apodized vortex coronagraphs for segmented telescopes 11 Telescope pupil Apodizer design Raw contrast Coronagraph design: Ruane et al. (2016) Jewell et al. (2017) Ruane et al. (2018) Supported by NASA ExEP SCDA study

12 Apodized vortex coronagraphs for segmented telescopes 12 Apodizer design Apodizer design (zoomed in) Prototype Gold microdot apodizer (10μm squares)

13 Apodized vortex coronagraphs for segmented telescopes 13 Apodizer design Apodizer design (zoomed in) Prototype Gold microdot apodizer (10μm squares)

14 Testbed integration 14 HCST as of May Left: with temporary enclosure. Right: without enclosure.

15 Testbed alignment and calibration 15 Deformable mirror calibrations PSF w/o coronagraph Raw contrast w/ coronagraph Subset of our kilo-dm from Boston Micromachines. Charge 8 vector vortex mask Nominal raw contrast of over 3-10 λ/d at λ = 780 nm (i.e. w/ DM flat ). Charge 8 liquid crystal vector vortex coronagraph. Circular pupil, no segmentation/obstructions. Better than specification of Wavefront error <10 nm rms per reflection. PSF motion of 0.02 λ/d rms at ~1 Hz.

16 Testbed alignment and calibration 16 Mounting scheme matters a lot! 6.6 nm rms 23.2 nm rms See poster by Dan Echeverri Wednesday evening

17 From first light to first dark 17 Small dark hole (8-10 λ/d) Half plane dark hole (4-10 λ/d) mean = mean = 10-6 log10(raw contrast) Monochromatic (λ = 780 nm)

18 Mid-spatial frequency wavefront stability tests 18 Short term stability test (4x speed) Long term stability test (1000x speed) 4 fps 0.02 fps Half plane dark hole (4-10 λ/d) Monochromatic (λ = 780 nm)

19 Mid-spatial frequency wavefront stability tests 19 Temporal σ of spatial mean = Temporal σ of spatial mean = Half plane dark hole (4-10 λ/d) Monochromatic (λ = 780 nm)

20 Mid-spatial frequency wavefront stability tests 20 Short term stability (2 min) Long term stability (60 min) RMS mid-spatial frequency wavefront stability (4-10 cycles): σ ω 1 2π 2 σ C µ C = 3 pm σ ω 12 pm (average over 4-10 cycles)

21 Ongoing upgrades: Heavy duty enclosure 21 New enclosure to stabilize the wavefront. Reduce air turbulence. Stabilize temperature. Eliminate the need for constant purging. Isolate from acoustic vibrations. Design by Alex Delacroix and Nem Jovanovic (Caltech)

22 Ongoing upgrades: Heavy duty enclosure 22 New enclosure to stabilize the wavefront. Reduce air turbulence. Stabilize temperature. Eliminate the need for constant purging. Isolate from acoustic vibrations. Stiff aluminum panels Design by Alex Delacroix and Nem Jovanovic (Caltech)

23 Ongoing upgrades: Heavy duty enclosure 23 New enclosure to stabilize the wavefront. Reduce air turbulence. Stabilize temperature. Eliminate the need for constant purging. Isolate from acoustic vibrations. Even stiffer, insulated aluminum panels Design by Alex Delacroix and Nem Jovanovic (Caltech)

24 Ongoing upgrades: Heavy duty enclosure 24 Image courtesy of Nicolas Levraud, SupOptique / Caltech (summer student)

25 Ongoing upgrades: Low-order wavefront sensing 25 Reflective Lyot stop Starlight OAPs Focal plane mask OAPs Apodizer Method based on Singh et al. (2017)

26 Future plans 26 Segmented DM to simulate primary mirror Second DM for control of pupil amplitude errors New coronagraph designs Spectrograph Planet source injection with unique spectral signature planet source stellar source gas cell LOWFS Atmosphere simulator FIU End-to-end spectral retrieval λ = nm for decadal missions (capability up to λ = 2500 nm)

27 Future plans 27 Segmented DM to simulate primary mirror Second DM for control of pupil amplitude errors New coronagraph designs Spectrograph Planet source injection with unique spectral signature planet source gas cell LOWFS FIU End-to-end spectral retrieval stellar source λ = nm for decadal missions (capability up to λ = 2500 nm) Atmosphere simulator See poster by Nemanja Jovanovic Two days ago

28 HCST is ready to rock n roll. Summary 28 We achieved raw contrast of to 10-6 depending on dark hole size in initial speckle nulling experiments. RMS wavefront stability is currently 3 pm over 2 min 12 pm over 60 min Will improve with new, beefy enclosure and with active loworder wavefront sensing and control. Immediate goal: Laboratory testing of apodized coronagraphs for segmented aperture space telescopes (supported by NASA ExEP). We look forward to collaborating.