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October 2010  •  Volume 3 Number 3

M1/M3 Optical Processing Continues

Top and middle: Components of the mirror cell polishing support system. Bottom: LSST M1/M3 blank during cell integration and testing, August, 2010.

Progress continues with production of the LSST primary (M1) and tertiary (M3) mirrors at the Steward Observatory Mirror Lab. The front surface has been generated and next we move into the grinding portion of the process.

Built into a single piece of glass, dual M1/M3 surfaces have been generated in the substrate (the dark inner circle on the accompanying photo indicates their locations). The next stage in moving toward their final polished state requires enhancements to the mirror cell polishing support system. Installation of 160 hydraulic actuators and load cells, 378 static supports, 64 ventilation fans, over 1500 air circulation nozzles, 1500 feet of hydraulic supply lines, 10,000 feet of electrical wire, and over 1000 electronic connectors is nearly complete. In total, these components enable proper support of the mirror during polishing and test, provide temperature monitoring and control of the glass, and core pressurization to minimize quilting over the mirror core cells. Also shown is a view of the underside of the mirror cell illustrating the actuators, fan units, circulation nozzles, and a sample of the wire routing required for operation of the polishing cell. There certainly is a lot going on behind closed doors. Soon the updated cell will be floated via air cart under the Large Optical Generating (LOG) machine to commence loose abrasive grinding.

Article written by Bill Gressler


LSST is a public-private partnership. Funding for design and development activity comes from the National Science Foundation, private donations, grants to universities, and in-kind support at Department of Energy laboratories and other LSSTC Institutional Members:

Adler Planetarium; Brookhaven National Laboratory; California Institute of Technology; Carnegie Mellon University; Chile; Cornell University; Drexel University; George Mason University; Google Inc.; Harvard-Smithsonian Center for Astrophysics; Institut de Physique Nucléaire et de Physique des Particules (IN2P3); Johns Hopkins University; Kavli Institute for Particle Astrophysics and Cosmology at Stanford University; Las Cumbres Observatory Global Telescope Network, Inc.; Lawrence Livermore National Laboratory; Los Alamos National Laboratory; National Optical Astronomy Observatory; Princeton University; Purdue University; Research Corporation for Science Advancement; Rutgers University; SLAC National Accelerator Laboratory; Space Telescope Science Institute; Texas A&M University; The Pennsylvania State University; The University of Arizona; University of California, Davis; University of California, Irvine; University of Illinois at Urbana-Champaign; University of Michigan; University of Pennsylvania; University of Pittsburgh; University of Washington; Vanderbilt University

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