Speckle Phase Sensing in Vortex Coronagraphy

Transcription

1 Speckle Phase Sensing in Vortex Coronagraphy Gene Serabyn Jet Propulsion Laboratory California Ins=tute of Technology Oct 6, 2014 Copyright 2014 California Institute of Technology. U.S. Government sponsorship acknowledged.

2 Collaborators SDC Chris Shelton Kent Wallace Michael BoKom Jonas Kühn Bertrand Mennesson Dimitri Mawet HCIT John Trauger Dwight Moody John Krist Eric Cady Brian Kern Kurt Liewer Dimitri Mawet

3 Outline The Palomar Hale telescope: P3K allows us to move our vortex work from a 1.5 m well- corrected subaperture to the full 5 m aperture Op=cal vor=ces with an on- axis telescope The double vortex configura=on The apodized vortex Unique related speckle reduc=on approaches? The new Stellar Double Coronagraph at Palomar Other vortex coronagraphs in the works HCIT vortex testbed news

4 The Op=cal Vortex Coronagraph A vortex phase mask applies a helical phase to focal plane Airy pattern Image Plane: Focal plane Pupil plane bypass vortex Input pupil φ = e imα through vortex Phase mask - High throughput (transparent) - Small inner working angle (0.9λ/D for charge=2) - Layout: same as classical Lyot coronagraph

5 The Problem with On- Axis Telescopes The vortex as a pupil transformer: Theory: Measurements:

6 The Problem with On- Axis Telescopes Diffraction from the secondary puts starlight back in the pupil

7 Solu=on I: The Dual- Stage Vortex Starlight reduced by (d/d) 4 Mawet et al. 2011

8 Net Result Telescope Adaptive Optics System V1 L1 V2 L2 0 (d/d) D d (d/d) 2-1 Starlight reduced by (d/d) 4 0 (d/d) 2

9 Speckle Phase Sensing with a Double Vortex Use of the residual central light as a reference beam: narrow beam à broad PSF Use phase-shifting interferometry between inner and outer pupils to measure speckle phases (apply four nπ/2 phase steps to center) t sec m-9 / (C(d ) 2 ) For an m = 5 star, and d = m, C = 10-6 ~ sec (Serabyn et al. 2011)

10 Speckle Phase Shifing vs. Self- Coherent Camera Both use extra starlight in Lyot plane from beyond the normal pupil use the science camera as the WFS camera SPS: Uses starlight in center of pupil Speckles remain spa=ally coherent Central piston phase shifs (to reference beam) modulate the speckles temporally Need ~four temporal phase shifs SCC: Uses light from beyond pupil spa=al fringes across speckles need more pixels across speckles Extended pupil must make it through the op=cal system

11 Infrared Coronagraphic Testbed (IRCT) Fiber source Collimating OAP Vortex mask 1 Input pupil mask Focusing OAP 1 Focusing OAP 2 Re-collimating OAP Lyot stop Vortex mask 2 CCD camera 2:1 relay Re-imaged pupil Re-imaging lens 11

12 The Double Vortex Coronagraph V1 Theory: V2 IRCT demo: Input Pupil 1 st Lyot Pupil After 1 st Lyot Stop 2 nd Lyot Pupil Serabyn et al. SPIE sometime in the past; also in prep.

13 (d/d) 4 Not Dark Enough? The Ring Apodized Vortex Coronagraph APODIZER Mawet et al Input Pupil VORTEX 2 nd Lyot Pupil Transmission reduced for high charge & large secondaries Theoretical thruput for trans. apodizer 13

14 Dual- vortex and RAVC Layouts Compared Dual vortex: Telescope Adaptive Optics System V1 L1 V2 L2 Apodized vortex: Telescope Adaptive Optics System V1 apodizer V1 Lyot

15 Palomar SDC Basic Layout Vortex2 OAP2 OAP3 Lyot2 Lyot1 To PHARO OAP1 OAP4 Input Fold Vortex1

16 SDC WFS elements Vortex 2 Pupil image reflective Lyot 2: central piston Reflective Lyot edge Tip-tilt IR quad cell Input Fold Vortex 1

17 SDC Layout (with Mirror Mounts) From P3K Vortex 1 to PHARO Pupil 1: Pupil 2: Vortex 2

18 The Assembled SDC

19 SDC mounts on the P3K bench P3K PHARO SDC

20 SDC closed and mounted on P3K

21 Pupil plane with Standard Cross V1 in place (thru V2 substrate) Open (V1, V2 off-axis) (thru V1, V2 substrates) V1 + V2 in place No Lyot mask in PHARO V1 + V2 in place

22 Image plane with Standard Cross Open (V1, V2 off-axis) (thru V1, V2 substrates) V1 in place (thru V2 substrate) V1 & V2 in place Linear (saturated) Linear Linear

23 SDC Plans 1) Double vortex Speckle phase shifing 2) Apodized vortex Self- coherent camera 3) LOWFS off Lyot 1 4) Other coronagraphs poss. 5) Visible wavelengths 6) MKID (Mazin)

24 Other Vortex Coronagraphs in Progress H- band vortex at Subaru/SCExAO Kühn, Singh, Jovanovich, Guyon With Pupil plane LOWFS L- band vortex at Keck Absil group, Keck AO team, Mawet, MaKhews Speckle nulling/electric field conjuga=on