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Key Types Introduction

Michelson Summer School on High-Contrast Imaging

Caltech, Pasadena

20-23 July 2004

Wesley A. TraubHarvard-Smithsonian Center for Astrophysics

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• C, IWA, OWA• types• perturbations

Reminders of main topics

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C

Ref: McCarthy & Zuckerman (2004); Macintosh et al (2003)

20 arcsec radius circle

K~20 magBkgd objects

7 arcsec wand

J~21 magBkgd object

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Search space: best to date

AiryHalo

1. Keck2. IRCAL, Lick AO, K3. Ks, AO, NACO, VLTI4. WFPC2, HST, I5. CFHT, AO, H6. Keck NICMOS, 10sig7. 50% det, HST, H8. XAO, 10m, R, 2007

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Earth & Jupiter-Saturn, 100 stars

Simulations by Bob Brown, STScI

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Earth & Jupiter-Saturn Regions

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Radial-velocity Stars

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RV stars and brown dwarfs

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1.8-m range

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TPF-C Range

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C, IWA, OWA

Contrast C: Example: C = 10-10 driven by Earth/Sun = 2x10-10.

Inner working angle IWA:Example: IWA = 3 /D driven by 1 AU/10pc = 0.100 arcsec.

Outer working angle OWA: Example: OWA = 48 /D driven by N = 96 actuator DM.

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Image-plane coronagraph simulation

Ref.: Pascal Borde 2004

1stpupil

1stimagewithAiry rings

mask, centered on starimage

2ndpupil

Lyotstop,blocks bright edges

2nd image,no star,brightplanet

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Wide-band (quadrant-phase) mask

€

π€

π

€

0

€

0

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Shaped-pupil mask

Kasdin, Vanderbei, Littman, & Spergel, preprint, 2004

Pupil: Spergel-Kasdin prolate-spheroidal mask

Image: dark areas < 10-10 transmission

Image: cut along the x-axis

v

u

A(x, 0) = exp(-(πx/)2)

A(0, y) = periodic & messy

x

y

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Discrete-mapped pupil (2): Densification

Entrance pupil, sparsely filled

FOV is small.

Image with many aliases Densified

pupil

Clean image,narrow FOV

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Continuous-mapped pupil

Compact star image, easily blocked

Input wavefront: uniform amplitude.

Mirror 1

Mirror 2

Output wavefront:prolate-spheroidal amplitude.

100 dB = 10-10 = 25 mag

Output image:prolate spheroid

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Nulling-shearing coronagraph

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Phase ripple and speckles

No DM:

With DM:

Phase ripples from primarymirror errors

Polishing errorson primary

Speckles generated by 3 sinusoidalcomponents of thepolishing errors

Pupil plane

Image plane

Image plane

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Phase + amplitude ripple and speckles h(u) = n (an+ian')cos(Knu) + (bn+ibn')sin(Knu) = total ripples

Describes all possible phase and amplitude ripples (= errors).

DM can give

I() = (0) + n [(bn’)2 + (an’)2 ] (k+Kn) bigger speckles

+ [ 0 + 0 ] (k-Kn)] smaller (zero) speckles