Project 1640 Coronagraph

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Project 1640 Coronagraph
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The Coronagraph
Achromatized APLC, optimized for 1.65
µm Apodizer 51 throughput with astrometric
grid Focal Plane Mask 5.37 ?/D at 1.65 µm 370
mas IWA of 200 mas Lyot Stop 2 downsized
from primary, negligible impact on
throughput ADC (designed by C. Shelton) covers
1-1.8 µm from 0 to 50, double prism design in
collimated beam Pupil Viewing camera to monitor
rejected starlight from Lyot Mask Tip/Tilt
system based on Hamamatsu InGaAs quad cell. 1kHz
update Provides f/143 beam to IFU lenslet array
(21 mas/lenslet)
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Basic Architecture
Apodizer (PPM), Focal plane mask (FPM) , Lyot
Stop
PPM FPM
Lyot Stop Final image
Apodizer transmission Throughput 50
Hard-edge stop Diameter 5 ?/D
Lyot Stop
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Apodizers, FPMs, Lyot Stops
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Updated Design Notes

• Improved the APLC design and identified issues
  not previously apparent (FPM f.o.v., e.g.)
• Proven the astrometric and photometric techniques
  with both lab and on-sky data

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Fabrication - PPM

• Chromium alloy microdots on glass
• MEMS Optical/Jenoptik, 1um, 2um microdots
• Zero order throughput to match APLC profile

MEMS apodizer
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Fabrication PPM WFE
3.4nm rms focus-subtracted
5.7nm rms
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Fabrication FPM
5 nm focus-subtracted, 0.5 nm roughness
Superpolished Si Etched 600 µm Hole
36 nm focus
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Fabrication FPM SEM
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• Edge roughness lt 2 ?m speced by GPI PDR
  tolerancing

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Project 1640 and Palomar 5-m AO System
1640 Dewar
AO System
Coronagraph Lyot Project Heritage
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Fold
Focal Plane mask
OAP2
Lyot Stop
OAP3
Fold
Final Sphere (above plate)
Atmospheric Dispersion Prisms
Infrasil window
OAP1
Apodizer
AO input beam
Fast steering mirror
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GPI Testbed Contrast

• Short exposure H

• Long exposure H

• Laser 1.55 um

Simulated w/30 nm WFE (expected testbed
performance)
Real Testbed Data
40 nm
20 nm
10 nm
5 nm
No WFE, real ?dot greys
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GPI Results - Contrast 1.55 micron

• 5 l/D radius

lt10-7
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GPI Results speckle scaling FeII 1.64um and
Laser 1.55 um
Scaled by wavelength
Unscaled
Centering issue akin astrometry Lyot movement
over 2 day gap
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10 second 1640 Coronagraphic IFU Exposure
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Smoothed to remove spectra