Adaptive Optics in Astronomy

The Space Coronagraph Optical Bench (SCoOB)

The University of Arizona is developing a new testbed for high-contrast imaging in a thermal vacuum chamber (TVAC) i.e., in space. When completed, the testbed will combine a vector vortex coronagraph (VVC) with a Boston Micromachines MEMS based Kilo-C (952-actuator) deformable mirror (DM) and a self-coherent camera (SCC), with the goal of raw contrast surpassing 10⁻⁸ at visible wavelengths.¹

Image of SCoOB with Boston Micromachines Kilo-C DM and other optical components,
including a focal plane mask (FPM), pupil viewer, camera, light source, mirrors and various lenses

Phase-Induced Amplitude Apodization (PIAA)

Scientists at NASA’s Ames Research Center have been developing a new high-performance coronagraph hardware that will decrease the amount of excess starlight leaking out, increasing the amount of potentially habitable exoplanets discovered by as much as 50%. The PIAA coronagraph utilizes a Boston Micromachines deformable mirror to suppress starlight close to a star, allowing it to distinguish planets in much closer orbits.²

1024-actuator, Kilo-DM by Boston Micromachines used in a PIAA coronagraph

High-contrast Imager for Complex Aperture Telescope (HiCAT)

The Space Telescope Science Institute (STScI) is developing an integrated solution for high-contrast imaging for unfriendly aperture geometries in space. More precisely, HiCAT aims at developing methods for starlight and diffraction suppression systems using Boston Micromachines deformable mirror technology, as well as wavefront sensing and control tools.³

The HiCAT optical design map using two Boston Micromachines DMs,
along with various other optical components. Refer to reference³ for more details.

High Contrast Imaging Testbed (HCIT)

NASA Jet Propulsion Laboratory (JPL) is developing and testing MEMS deformable mirror technology for future space-based exoplanet imaging missions. JPL’s HCIT facility is testing BMC Kilo and 2K deformable mirrors and control electronics for spaceflight capability and environmental testing. The scope of the program is to pave the way for a flight-ready wavefront control system.⁴

Boston Micromachines Kilo-DM in the HCIT

Visible Light Laser Guidestar Experiments (ViLLaGEs)

ViLLaGEs is a MEMS based visible-light wavelength adaptive optics (AO) testbed on the Nickel, 1-meter telescope at the Lick Observatory. The testbed is operated by the University of California and is situated on the summit of Mount Hamilton, California. ViLLaGEs utilized a Boston Micromachines 140 actuator-count deformable mirror in proving and successfully advancing AO technology for visible-light wavelength applications.⁵

ViLLaGEs optical layout using the Boston Micromachines Multi-DM,
and various other optical components. Refer to reference⁵ for more details.

References:

1. “The space coronagraph optical bench (SCoOB): 2. wavefront sensing and control in a vacuum-compatible coronagraph testbed for spaceborne high-contrast imaging technology.”, Van Gorkom, Kyle, et al., Space Telescopes and Instrumentation 2022.
2. “NASA designs new space telescope optics”, article about Phase-Induced Amplitude Apodization (PIAA) by Ruth Dasso Marlaire, NASA.
3. High-contrast Imager for Complex Aperture Telescope (HiCAT).
4. “MEMS DM developments in HCIT”, G. Ruane, E. Bendek, C. Mejia Prada, P. Poon, B. Peters, D. Liu, and others, Jet Propulsion Laboratory, California Institute of Technology.
5. “ViLLaGEs: opto-mechanical design of an on-sky visible-light MEMS-based AO system”, Grigsby, Bryant, et al., Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation.

Boston Micromachines deformable mirrors (DMs) are used in various telescopes and observatories around the world. Our high-actuator count DMs are used for exoplanet discovery using coronagraphy. A coronagraph is an optical instrument that blocks light from the center of a telescope beam, allowing light from surrounding sources to pass through. This optical technique is used to find extrasolar planets and circumstellar disks around nearby stars.

Example of a coronagraph blocking light from a star

The following telescope instruments utilize coronagraphy with Boston Micromachines DMs for exoplanet discovery:

SCExAO at Subaru Telescope

The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system is permanently installed at the Subaru Telescope, which is an 8.2-meter optical-infrared telescope located on the summit of Maunakea, Hawaii. It is operated by the National Astronomical Observatory of Japan (NAOJ).

Subaru Telescope of NAOJ, located on Maunakea in Hawaii

SCExAO’s main goal is to image exoplanets and disks around nearby stars by using coronagraphy to block starlight, while keeping the image of a planet mostly unattenuated. The instrument utilizes a 2040 actuator (2K) MEMS DM from Boston Micromachines, along with other optical components, to achieve its goal.

Boston Micromachines 2K DM installed in the SCExAO system (NAOJ Projects: SCExAO)

Gemini Planet Imager

The Gemini Planet Imager (GPI) is a dedicated planet-finding optical instrument built for the Gemini South Telescope in Chile. GPI is designed to directly image and characterize extrasolar planets orbiting nearby stars. The instrument uses advanced adaptive optics with our high-actuator count DM that provides starlight-blocking capability. Various precision optical elements and an infrared spectrograph are also built into the instrument.

Gemini South Telescope located in Chile

Boston Micromachines has built a custom 4096 actuator (4K) DM for GPI that has been used to detect multiple exoplanets. An example is 51 Eri b, which was discovered in 2014 by GPI. At 2 Jupiter masses, it is the coolest and lowest-mass imaged exoplanet to date. The graphical image below uses 5 images taken over 4 years using GPI. In these 4 years, the planet is curving into the star, allowing us to see the gravitational pull of the star on this exoplanet.

51 Eri b imaged by the GPI (Credit: Jason Wang/Gemini Planet Imager Exoplanet Survey)

MagAO-X

MagAO-X, the successor to MagAO, is an extreme adaptive optics system on the Magellan Clay Telescope that enables high-contrast imaging at visible and near-infrared wavelengths. The instrument utilizes a 2040 actuator (2K) MEMS DM from Boston Micromachines, operating at 3.63 kHz for high-order wavefront control as part of the “tweeter” system.

MagAO-X optical testbed (xwcl.science)

Keck Planet Imager and Characterizer (KPIC)

KPIC is an instrument in the Keck II Telescope, installed at the Keck Observatory in Hawaii. Designed by Caltech, the instrument enables high spectral resolution characterization of directly imaged exoplanets in the near-infrared. The deployment of KPIC was phased, with phase II introducing a series of upgrades for the telescope’s adaptive optics system, including a 952 actuator Kilo-DM from Boston Micromachines.

KPIC coronagraphy (ET Lab at Caltech: KPIC)

Demonstrated Projects

Planet Imaging Concept Testbed Using a Rocket Experiment (PICTURE)

A NASA sounding rocket for high-contrast imaging with a visible nulling coronagraph, the PICTURE payload has made two suborbital attempts to observe the warm dust disk inferred around Epsilon Eridani. The rocket was designed to significantly advance the science and technology supporting exoplanet research, the PICTURE-B mission of the Lowell Center for Space Science and Technology, at the University of Massachusetts Lowell successfully launched and returned to Earth in November 2015. The Boston Micromachines DM used in the rocket was a continuous surface Kilo-DM, with 1024 actuators, and 1.5 µm stroke. The observations from the experiment demonstrated the first operation and measurement of a DM for high-contrast imaging in space with reflected light.¹

Image courtesy of E. Douglas, University of Massachusetts Lowell

The third phase of this experiment, the Planetary Imaging Concept Testbed Using a Recoverable Experiment – Coronagraph (PICTURE-C), is the first balloon-borne experiment designed to directly image debris disks and exozodiacal dust around nearby stars from a high-altitude balloon using a vector vortex coronagraph. PICTURE-C took its first flight in September 2019, where it flew for a total of 20 hours. The second flight was successfully launched in the summer of 2023, followed by results from the experiment in August 2023. PICTURE-C is utilizing a 952-actuator count Kilo-DM for tackling high-order aberrations.²

PICTURE-C being lifted to the stratosphere by an immense NASA balloon (Credit: Christopher Mendillo)

Deformable Mirror Demonstration Mission (DeMi)

Boston Micromachines was part of the DeMi mission, lead by MIT STAR Lab, in a collaboration effort with Aurora Flight Sciences. The mission used a CubeSat, a class of miniaturized satellites, with our Multi-DM MEMS-based DM installed in it to validate and demonstrate wavefront control for a precision of less than 100 nm RMS to be used in space for high-contrast astronomical imaging. The CubeSat was retired in March 2022 after a successful two-year mission. Click here to read more about the DeMi mission.

Artist’s rendition of the DeMi CubeSat in orbit

Our DMs were also baselined for two of the biggest NASA space-based telescope project concepts, HabEx and LUVOIR.  These concepts have recently been retired in favor of the new Habitable Worlds Observatory, which Boston Micromachines has been baselined as the deformable mirror technology.  Below are details on HabEx and LUVOIR:

Conceptual Projects

Habitable Exoplanet Observatory (HabEx)

HabEx is a concept for a space telescope mission for directly imaging planetary systems around Sun-like stars for exoplanet discovery. One of the instruments designed for HabEx is a coronagraph, fitted with a high-actuator count MEMS based DM. Click here to learn more about the instrument.

HabEx telescope flying in formation with the Starshade in place (NASA)

Large Ultraviolet Optical Infrared Surveyor (LUVOIR)

LUVOIR is also a concept mission for a highly capable, multi-wavelength space observatory. The mission encompasses a broad range of science and discovery, from the formation of the galaxy and its evolution, to remote sensing of solar systems and exoplanet discovery. Click here to check out the ambitious LUVOIR mission.

LUVOIR-A observatory with a 15 m telescope (NASA GSF)

References:

1. “Wavefront sensing in space: flight demonstration II of the PICTURE sounding rocket payload,” Ewan S. Douglas, Christopher B. Mendillo, Timothy A. Cook, Kerri L. Cahoy, Supriya Chakrabarti, J. Astron. Telesc. Instrum. Syst.
2. “Polarization aberration analysis for the PICTURE-C exoplanetary coronagraph,” Christopher B. Mendillo, Glenn A. Howe, Kuravi Hewawasam, Jason Martel, Timothy A. Cook, and Supriya Chakrabarti, J. Astron. Telesc. Instrum. Syst.