May 23, 2005
UCSC dedicates new Laboratory for Adaptive
Optics facilities
By Tim Stephens
Scientists in the Laboratory for Adaptive Optics at UCSC are
developing extraordinarily precise optical systems that will
enable astronomers to capture images of planets far beyond our
solar system and build the next generation of giant telescopes.
On May 17, campus officials and distinguished visitors dedicated
new facilities for the laboratory and celebrated its achievements.
UCO/Lick director Joseph Miller (right) presented
a framed photo of Lick Observatory to Edward Penhoet, president
of the Gordon and Betty Moore Foundation, at the dedication
of UCSC's Laboratory for Adaptive Optics.
Photo: Tim Stephens |
Graduate students Katie Morzinski and Stephen Mark Ammons
work in the Laboratory for Adaptive Optics at UCSC
Photo: Jim MacKenzie, UCSC |
"The Laboratory for Adaptive Optics is a technological
powerhouse for observational astronomy, harnessing complex technologies
from a variety of disciplines to enable us to see the cosmos
with greater precision and clarity," said UCSC Chancellor
Denice D. Denton.
Established in 2002 with a $9.1 million grant from the Gordon
and Betty Moore Foundation, the Laboratory for Adaptive Optics
(LAO) develops innovative instrumentation to apply adaptive
optics technology in astronomy. Adaptive optics sharpens the
vision of ground-based telescopes by removing the blurring effects
of turbulence in the Earth's atmosphere.
"Adaptive optics is one of the most exciting developments
in ground-based astronomy in the last decade. It is crucial
to very important science being planned for existing large telescopes
and absolutely essential to the next generation of giant telescopes,"
said Joseph Miller, director of UC Observatories/Lick Observatory
(UCO/Lick), which oversees the LAO.
UCO/Lick already operates world-class technical facilities
for astronomical instrumentation at UCSC, including an optical
lab and shops, an engineering lab, and an advanced detector
lab.
"Now we have added a major laboratory for advancing the
technology of adaptive optics--the only such lab associated
with a university in the United States. It gives us the ability
to develop and test new experimental techniques and equipment
here on campus. This is a dream come true for me," Miller
said.
The LAO began operations in temporary facilities at the Lick
optical lab before moving to its current location on the ground
floor of Thimann Laboratories. Renovation of the facilities
in Thimann was just completed this month.
The lab occupies two rooms with controlled temperature and
lighting conditions and a clean environment to protect sensitive
equipment from contamination. The instrument tables where researchers
conduct experiments float on a cushion of air to isolate them
from vibrations. The facilities also include a Class 100 clean
room where optical instruments can be built.
"The lab has all the precision optical measurement tools
we need to test advanced adaptive optics systems," said
LAO principal investigator Claire Max, a professor of astronomy
and astrophysics at UCSC.
"The techniques we are exploring are well beyond the current
state of the art, so we need to be able to put these systems
through their paces in the lab before we try to take them to
a telescope," she said.
Max is also the director of the Center for Adaptive Optics
(CfAO), headquartered at UCSC and established in 1999 by the
National Science Foundation. The CfAO focuses on the advancement
of adaptive optics technology in both astronomy and vision science.
The LAO complements CfAO, providing a testing ground for concepts
developed by CfAO researchers, Max said.
The lab also provides an opportunity for UCSC students, both
undergraduates and graduate students, to get involved in practical
astronomy and the development of astronomical instruments, said
LAO director Don Gavel.
"It is an interdisciplinary effort, so it brings together
faculty and students from different programs on campus,"
Gavel said.
Much of the work in the LAO focuses on two major goals, known
as extreme adaptive optics and multiconjugate adaptive optics.
Extreme AO pushes the limits of adaptive optics in an effort
to give astronomers the ability to see the dim light from a
planet orbiting a bright star.
Astronomers have discovered more than 100 planets outside our
solar system (called extrasolar planets) by indirect methods
that detect the gravitational tug of the planet on its parent
star. To actually see an extrasolar planet, however, requires
an adaptive optics system that can prevent scattered light from
the parent star from obscuring the nearby planet.
Only one extrasolar planet has been photographed, and that
planet orbits a brown dwarf, a "failed star" not nearly
as bright as ordinary stars such as the Sun. Extreme AO aims
to get images so sharp that a planet can be seen next to a star
more than a billion times brighter than the planet.
Astronomers could then analyze the light from the planet for
clues to its composition and other properties.
An adaptive optics system precisely measures how light gets
distorted as it passes through the Earth's turbulent atmosphere.
The system then calculates the corrections needed to counteract
that distortion, applies the corrections by bouncing the light
gathered by the telescope off a deformable mirror, and repeats
the whole process hundreds of times per second. The deformable
mirror is a key component, constantly changing shape to counteract
the blurring effects of the atmosphere.
The LAO is at the forefront of the development of deformable
mirrors based on MEMS technology. MEMS, which stands for micro-electro-mechanical
systems, is a revolutionary technology that uses silicon-based
fabrication techniques (like those used to make computer chips)
and micromachining to make integrated devices that combine sophisticated
electronics with moving parts. The LAO has been testing a MEMS
mirror with 1,000 actuators, tiny elements that move up and
down to change the shape of the mirror, which is about the size
of a postage stamp.
"For extreme AO, we need a deformable mirror that is very
optically smooth. We've got a beautiful setup for testing these
mirrors and they are getting better and better. We will soon
begin testing one with 4,000 actuators on the mirror, which
is what we think we need to build an extreme AO system,"
Max said.
Multiconjugate AO aims to increase the field of view, or the
size of the area that is corrected by the AO system. Current
AO systems use a single point-source of light--either a bright
star or an "artificial guide star" created by a laser--as
a reference for measuring atmospheric blurring. The system can
only apply corrections for a relatively small region around
that reference point. But the field of view could be increased
by using multiple laser guide stars, Gavel said.
"With multiple guide stars, you can effectively do tomography
of the atmosphere, similar to medical imaging techniques like
CT scans, to extend adaptive optics over a wide field of view,"
he said.
Future giant telescopes now in the planning stages will require
this type of adaptive optics. But the complexity of the system
increases considerably with the need to integrate measurements
from multiple guide stars and coordinate multiple deformable
mirrors.
"There are different methods for doing this, and we will
be testing them to see which does better," Max said.
With its support for the LAO, the Moore Foundation has provided
vital resources for researchers to advance the state of the
art of adaptive optics, said Miller.
"This grant allows us to fully equip the lab and get it
off to a great start, giving us time to make it self-sustaining,"
he said.
In addition to funding the LAO, the Moore Foundation has provided
$35 million in grants for the design phase of a giant telescope
project: the Thirty Meter Telescope, a joint undertaking of
UCO/Lick, the California Institute of Technology, the Association
of Universities for Research in Astronomy, and the Association
of Canadian Universities for Research in Astronomy.
Established in September 2000, the Gordon and Betty Moore Foundation
seeks to develop outcome-based projects that will improve the
quality of life for future generations. The foundation has organized
the majority of its grantmaking around large-scale initiatives
in three areas of interest to the Moores: environmental conservation,
science, and the San Francisco Bay Area.
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