Richard F. Caris Mirror Lab

Richard F. Caris Mirror Lab
Name	Richard F. Caris Mirror Lab
Established	1985
Director	Buell Jannuzi
Parent organization	University of Arizona
Location	Tucson, Arizona
Field	Optics, Astronomy, Precision engineering

Richard F. Caris Mirror Lab. It is a world-renowned optical science and engineering facility, part of the Steward Observatory at the University of Arizona. Specializing in the production of giant, lightweight primary mirrors for the world's most advanced telescopes, the lab pioneered the revolutionary spin-casting technique using borosilicate honeycomb structures. Its mirrors are integral to many leading astronomical observatories, enabling groundbreaking discoveries across the electromagnetic spectrum.

History and Founding

The origins of the lab trace back to the 1980s under the leadership of J. Roger P. Angel at Steward Observatory. Seeking to overcome the limitations of traditional solid glass mirrors, Angel developed the concept of spin-casting large, lightweight borosilicate glass mirrors in a rotating furnace. Initial experiments proved successful, leading to the formal establishment of a dedicated mirror lab beneath the Arizona Stadium in 1985. The facility was later renamed in honor of major benefactor Richard F. Caris, a philanthropist and University of Arizona alumnus. This period of innovation positioned the University of Arizona at the forefront of astronomical optics, building on a legacy that included earlier contributions from astronomers like Bart Bok.

Mirror Fabrication Process

The lab's signature process begins with melting thousands of hexagonal borosilicate glass blocks, known as E6 glass, inside a unique rotating furnace. As the furnace spins, centrifugal force forms the molten glass into a concave parabolic shape, significantly reducing the subsequent grinding time. Once cooled, the resulting structure is a rigid, lightweight honeycomb core sandwiched between two glass facesheets. The rough mirror blank then undergoes years of precise grinding and polishing using custom-built machines like the Stressed Lap Polisher. Final steps involve applying a reflective coating of aluminum or protected silver in a large vacuum chamber to create the highly reflective surface essential for capturing faint astronomical objects.

Major Projects and Telescopes

The lab has produced mirrors for many of the most powerful telescopes on Earth. Its first major success was the twin 8.4-meter mirrors for the Large Binocular Telescope on Mount Graham. It cast the 6.5-meter mirrors for the Magellan Telescopes at Las Campanas Observatory in Chile. A flagship achievement is fabricating the seven 8.4-meter segments for the Giant Magellan Telescope, a next-generation instrument under construction in Chile. Other notable projects include the 3.5-meter mirror for the ARC Telescope at Apache Point Observatory and the 6.5-meter mirror for the MMT upgrade. These instruments are often deployed at premier sites like the Fred Lawrence Whipple Observatory.

Technology and Innovations

Beyond spin-casting, the lab is a hub for advanced optical technology. It developed the Stressed Lap Polishing technique, which uses a flexible polishing lap that bends to perfectly match the mirror's changing curvature. For the Giant Magellan Telescope, engineers pioneered the process of casting off-axis mirror segments, which are asymmetrical and far more complex to produce. The lab also utilizes sophisticated interferometry for metrology, working with instruments like the SCOTS system. Research extends into novel mirror materials and support systems, often in partnership with institutions like the NASA-funded Center for Astronomical Adaptive Optics.

Facilities and Location

The lab operates from a distinctive underground facility located directly beneath the east side of Arizona Stadium on the campus of the University of Arizona in Tucson. This location provides natural thermal stability and vibration isolation critical for precision work. The complex houses the world's only large spin-casting furnace capable of producing 8.4-meter mirrors, multiple polishing machines, and one of the world's largest optical coating chambers. Adjacent spaces include optical testing tunnels and clean rooms. The facility's unique position is a noted feature for attendees of Arizona Wildcats football games.

Collaborations and Impact

The lab collaborates with a global consortium of universities, research institutions, and government agencies. Major partnerships include the GMTO Corporation for the Giant Magellan Telescope, the Carnegie Institution for Science for the Magellan Telescopes, and international groups for the Large Binocular Telescope. Its work has directly impacted projects funded by the National Science Foundation, the Department of Energy, and NASA, including concepts for future space telescopes. By providing the essential optics for cutting-edge observatories, the lab's contributions have enabled seminal discoveries in exoplanet research, cosmology, and galaxy evolution, solidifying the University of Arizona's status as a leader in astronomical instrumentation.

Category:University of Arizona Category:Optics organizations Category:Astronomical observatories in Arizona Category:Research institutes in the United States