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Steward Mirror Lab Photo © Joe Orman |
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The mirror lab is located
under the football stadium bleachers on the University of Arizona campus in
Tucson, Arizona. |
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6½ meter mirror |
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Top of casting furnace |
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A pair of 8.4 meter mirrors for the Large Binocular Telescope |
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Our tour guide, Peter Wehinger, by an 8.4 for scale |
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Parabolic surface on an 8.4 |
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Underneath an 8.4 meter mirror |
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A display of the ceramic
honeycomb forms and chunk of borosilicate glass. When melted in the furnace, the
glass will flow over and between the forms that fill the mold |
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A 6.5-meter diameter mirror in
the furnace. Top of furnace has been raised off by crane and stored in bay at
upper right. Peak temperature is 1180°C. Photo © Joe Orman |
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Dr. Peter Wehinger, Staff
Astronomer at Steward Observatory, acted as our tour guide. He is standing at
the edge of the furnace's rotating portion. Rotation produces parabolic shape on
upper surface of glass -- the shape required to focus light. |
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After casting, the ceramic
forms are removed, leaving a lightweight honeycomb mirror blank. These are the
two 8.4-meter (27-foot) diameter mirrors for the Large Binocular Telescope (LBT)
on Arizona's Mt. Graham. Photo © Joe Orman |
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Each LBT mirror weighs 10
tons. The mirror on the left is "face-up," while the mirror on the right is
"face-down." They will be the world's largest working in tandem. Photo © Joe Orman |
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The LBT will have the
light-gathering capability equivalent to an 11.8-meter diameter mirror (more
than any other single telescope), and the resolution of a 22.8-meter diameter
mirror (10 times sharper resolution than the Hubble Space Telescope). |
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The underside of the
"face-down" mirror, showing how the fixture used to move the mirror is actually
glued to the mirror surface. Photo © Joe Orman |
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This is the shaped lap
polishing tool under construction. Two computer-controlled laps will change
their shape as they move across the face of the mirror. The final surface will
be accurate to less than one-millionth of an inch! After installation in the
telescope, each mirror will be coated with a thin layer of metal to form the
telescope's reflective surface. |
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Assemblies that will hold the polishers |
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Close-up of assembly |
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These electronically
controlled actuators will be positioned behind the mirror to properly support
the mirror in different orientations. |
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