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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
working in lab

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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