NASA SBIR: Proximity Glare Suppression Using Carbon ......•Developed catalyst enhancer to make...

NASA SBIR: Proximity Glare Suppression Using Carbon

Nanotubes

John Hagopian

November 7, 2019Lambda Consulting, LLC/Advanced Nanophotonics Inc.

Phase II Goals• Improved apodizers

– Higher resolution patterning– Darker nanotube growth– Improved reflectivity of base layer stack– Grayscale apodizers

• Improved Lyot Stops– Darker short nanotube growth– Higher resolution features

• Improved nanotube filled paint for large area application– Greater than factor of three improvement on Z306

• Improved robustness• Lower temperature growth

– Plasma Enhanced CVD with activated catalysts– Flash CVD process below current 650 C growth temperature

compatible with apodizer reflective stack 2Lambda Consulting, LLC/Advanced Nano

SBIR Customers and Collaborators• Phase II Customers– Remi Soummer – STScI; Coronagraphy Test Bed

– Eduardo Bendek – LUVOIR Ames NASA Test Bed

– NASA GSFC – PACE/Ocean Color Radiometer Team

– Hari Subedi – GSFC Test Bed

– Ron Shiri/Jeff Livas - Laser Interferometer Space Antenna (LISA)

• Collaborators– Peter Chen – Lightweight Telescopes

3Lambda Consulting, LLC/Advanced Nano

Why Carbon Nanotubes?• Carbon nanotubes are the darkest material

made by man– Application of carbon nanotubes to instrument

components can significantly improve the performance of scientific instruments• Enabling new science• Better observational efficiency• Simplification of stray light control

– This SBIR focused fabrication on delivering components for evaluation in coronagraphic test beds to investigate technologies for Exoplanet science• Shaped Lyot Stops• Reflective apodizers• Grayscale and Fresnel Mirrors


Deliverable: Shaped Lyot Stops• Lyot Stops occult on-axis light from a star at an intermediate focal plane

This allows coronagraphic instruments to view very dim planets orbiting the stars

Primary Technical Goals:

• Fabricate a sharp edged Lyot Stops using lithographic masks and wet etching to produce an optically flat and accurately dimensioned substrate

• Apply nanotube deposition to Lyot Stops – deposit short growth, dark nanotubes precisely

• For both deliverables:• Robustness of adhesion to survive exposure to space flight qualification

and the space environment; vibro-acoustic and thermal. However, the CNT coating and all other available CNT growths will remain a “no-touch” coating that will degrade with contact


Shaped Lyot Stops• Design and fabrication –– Phase II - Worked with Eduardo Bendek from NASA Ames

Institute to design Lyot Stops for use in the LUVOIR aperture– Converted design to GDS file to create an e-beam written

lithographic mask for precise patterning of mask in silicon– Patterned and etched Lyot stops from 300 micron thick

silicon wafers– Controlled etch process to create a 57 degree edge angle for

a sharp edged stop with precise dimensional accuracy– Developed short growth catalyst and applied it to both sides

of Lyot Stops – Successfully grew short nanotubes on both sides of Lyot

Stops


Shaped Lyot Stops

Phase II Complex Lyot Stop Design for LUVOIR Test Bed With and without Segments


Developed Nanotube Coating for PACE Ocean Color Instrument (OCI) under Phase II SBIR

-2

-1.5

-1

-0.5

0

0.5

1

1.5

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0 500 1000 1500 2000 2500 3000

%T Through Blocking Layer and CNT on both sides

WL (nm)

T %

• 100% blocking while maintaining significantly better reflectance than alternate coatings

• Slit width is critical to microns requiring precise control of nanotube length

• Nanotubes uniformly grown on both sides• Developed catalyst enhancer to make short

nanotubes the darkest measured per length


Improved Adhesion

Lambda Consulting, LLC/Advanced Nano 9

- Pathfinder slits cracked during bolt down due to lack of flexure interface

- There was no delamination of nanotubes at crack locations

- Pathfinder slits cracked during bolt down due to lack of flexure interface

- There was no delamination of nanotubes at crack locations

- No loose carbon nanotubes were observed after slit damage

- Contrast stretched image of OCI Engineering Unit entrance slit

Deliverable: Reflective Apodizer• A patterned reflective apodizer resides in the pupil plane of a

coronagraph and absorbs diffracted light from the structures in a telescope; the secondary mirror baffle, struts and segment edges. This creates a “Dark Hole” at some field positions where we may view the extremely dim companion planets

Primary Technical Goals:

• Excellent apodizer mirror surface figure –Develop a mirror substrate and nanotube growth process compatible with the carbon nanotube growth that results in better than diffraction limited performance

• High apodizer reflectivity – develop a coating compatible with the carbon nanotube growth process (initially at 750 C)

• Patterned dark growth – pattern and grow nanotubes with features as small as few microns to support absorption of diffracted light


Making an Apodizer


Phase II Apodizer Improvements• Darker nanotube growth• Higher reflectance silver• Higher resolution patterning• Excellent surface figure


Darker Nanotubes; Shinier Silver• CVD parameters balanced for darker

nanotubes on apodizers while minimizing degradation to silver reflective layer


Mirror Surface Figure after Growth


Data file vs Apodizer image; can you tell?

Lambda Consulting, LLC/Advanced Nano16

HiCAT – HCI on segmented apertures

Coro

nagr

aph

WF

sens

ing

& c

ontr

ol

System-level performance

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• High Contrast Imaging (HCI)

• Coronagraphy (APLC) for segmentation

• Multiple sensors and control loops for all elements

• Sensor and control interactions with coronagraph

• Contrast goal: 10-7 to 10-8 in air

Iris AO segmented DM

Boston continuous DMs

IrisAODM1

DM2

Apodizer

Apodizer

FPM

Lyot stopTDEM white paper: Remi Soummer PIhttps://exoplanets.nasa.gov/exep/technology/TDEM-awards/

https://exoplanets.nasa.gov/exep/technology/TDEM-awards/

Performance of Phase I Apodizer in HiCat Test Bed

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This run:7.5 x 10-7

Current typical:5 x 10-7

1 x 10-7 in half-DZ

TDEM white paper: Remi Soummer PIhttps://exoplanets.nasa.gov/exep/technology/TDEM-awards/

HiCAT Preliminary Contrast with Phase II Apodizer

https://exoplanets.nasa.gov/exep/technology/TDEM-awards/

GSFC Test Bed First Light


Simulated Null

First Light

Carbon Nanotube Based Paint

• Develop a carbon nanotube-based paint darker than Z306 for aerospace based applications

• The objective of this subtask is to develop a process or processes to coat large area substrates (25 cm x 25 cm or larger) with aligned carbon nanotubes oriented normal to the substrate. The coating should provide a high degree of absorption (<1%) over the uv-ir wavelength range, adhere well to commonly used aerospace materials such as aluminum, titanium, or carbon fiber composite materials, and can be applied at room temperature without the need for special enclosures (eg. vacuum) or hazardous chemicals.


2 Paint process developed

• In the wet process, CNTs are dispersed in a solvent, then attracted to the target by low power, low frequency (kHz) AC and low (102 V) voltage DC fields

• In the dry process, CNT powder is directed to the target by high power RF (MHz)and/or high (103 V) voltage DC fields

Lambda Consulting, LLC/Advanced Nanophotonics, Inc 22

Apparatus for Wet Deposition Process


Apparatus for Dry Deposition Process


Nanotube Paint Samples


Nanotube Filled Paint• Goal of 3x improvement over Z306 achieved


Work in Progress• Grayscale– Grayscale patterning hybrid with nanotubes– Alternatively; hybrid phase mirror with nanotubes

• Focal Plane Mask– Etched focal plane mirror with phase dimple

• Reduced temperature of nanotube growth–Working to extend growth temperature below 450C

• Conformal coating– Developed new process for conformal nanotube

growth using Atomic Layer Deposition of catalyst27Lambda Consulting, LLC/Advanced Nano

NASA SBIR: Proximity Glare Suppression Using Carbon ......•Developed catalyst enhancer to make...

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