Abstract
The cost of an eight-metre telescope is still too high for most national observatories. Cost reductions must involve new technology for the primary mirror: its material and figuring, its mass, handling and the aluminising plant. Our scheme which addresses these problems uses some features of the Keck technology, but is simplified. Necessary R&D can be carried out at our facility in London. We consider a segmented mirror in which the segments are radially-cut sectors. The sectors for an eight-metre aperture will fit inside a four-metre aluminising plant (which already exists on some sites, and in any event is cheaper than an eight-metre plant). Zero-expansion material (glass-ceramic or fused silica) may be used. The model thickness is about ten centimetres. The proposed method of production is to figure the whole set assembled as a single mirror. No cutting takes place after figuring. We consider three such figuring methods including inverted polishing and a new 'stressed mirror figuring' approach. (These methods are partly applicable to monolithic mirrors). In one of these methods, the support system of our assembled mirror on the machine may perhaps be re-used on the telescope. We expect that the testing and figuring cycle can be controlled sufficiently accurately to provide mirror segments which are interchangeable between successive batches. The economies produced by this technology may also be effective for smaller telescopes.
| Original language | English |
|---|---|
| Title of host publication | Advanced Technology Optical Telescopes IV |
| Subtitle of host publication | SPIE Astronomical Telescopes and Instrumentation for the 21st Century 1990 |
| Editors | Lawrence D. Barr |
| Publisher | SPIE |
| Pages | 586-596 |
| Number of pages | 11 |
| ISBN (Print) | 081940280X, 9780819420806 |
| DOIs | |
| Publication status | Published - 1 Jul 1990 |
| Externally published | Yes |
| Event | Advanced Technology Optical Telescopes IV - Tuscon, United States Duration: 12 Feb 1990 → 16 Feb 1990 Conference number: 4 |
Publication series
| Name | Proceedings of SPIE - The International Society for Optical Engineering |
|---|---|
| Volume | 1236 pt 2 |
| ISSN (Print) | 0277-786X |
Conference
| Conference | Advanced Technology Optical Telescopes IV |
|---|---|
| Country | United States |
| City | Tuscon |
| Period | 12/02/90 → 16/02/90 |
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Technology for eight-metre primary mirrors. / Bingham, Richard G.; Walker, David D.; Diego, Francisco.
Advanced Technology Optical Telescopes IV: SPIE Astronomical Telescopes and Instrumentation for the 21st Century 1990. ed. / Lawrence D. Barr. SPIE, 1990. p. 586-596 (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 1236 pt 2).Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
TY - GEN
T1 - Technology for eight-metre primary mirrors
AU - Bingham, Richard G.
AU - Walker, David D.
AU - Diego, Francisco
PY - 1990/7/1
Y1 - 1990/7/1
N2 - The cost of an eight-metre telescope is still too high for most national observatories. Cost reductions must involve new technology for the primary mirror: its material and figuring, its mass, handling and the aluminising plant. Our scheme which addresses these problems uses some features of the Keck technology, but is simplified. Necessary R&D can be carried out at our facility in London. We consider a segmented mirror in which the segments are radially-cut sectors. The sectors for an eight-metre aperture will fit inside a four-metre aluminising plant (which already exists on some sites, and in any event is cheaper than an eight-metre plant). Zero-expansion material (glass-ceramic or fused silica) may be used. The model thickness is about ten centimetres. The proposed method of production is to figure the whole set assembled as a single mirror. No cutting takes place after figuring. We consider three such figuring methods including inverted polishing and a new 'stressed mirror figuring' approach. (These methods are partly applicable to monolithic mirrors). In one of these methods, the support system of our assembled mirror on the machine may perhaps be re-used on the telescope. We expect that the testing and figuring cycle can be controlled sufficiently accurately to provide mirror segments which are interchangeable between successive batches. The economies produced by this technology may also be effective for smaller telescopes.
AB - The cost of an eight-metre telescope is still too high for most national observatories. Cost reductions must involve new technology for the primary mirror: its material and figuring, its mass, handling and the aluminising plant. Our scheme which addresses these problems uses some features of the Keck technology, but is simplified. Necessary R&D can be carried out at our facility in London. We consider a segmented mirror in which the segments are radially-cut sectors. The sectors for an eight-metre aperture will fit inside a four-metre aluminising plant (which already exists on some sites, and in any event is cheaper than an eight-metre plant). Zero-expansion material (glass-ceramic or fused silica) may be used. The model thickness is about ten centimetres. The proposed method of production is to figure the whole set assembled as a single mirror. No cutting takes place after figuring. We consider three such figuring methods including inverted polishing and a new 'stressed mirror figuring' approach. (These methods are partly applicable to monolithic mirrors). In one of these methods, the support system of our assembled mirror on the machine may perhaps be re-used on the telescope. We expect that the testing and figuring cycle can be controlled sufficiently accurately to provide mirror segments which are interchangeable between successive batches. The economies produced by this technology may also be effective for smaller telescopes.
KW - Economics
KW - Observatories
KW - Optical Materials - Processing
KW - Telescopes - Accessories
KW - Eight-Meter Telescopes
KW - Inverted Polishing
KW - Monolithic Mirrors
KW - Primary Mirrors
KW - Segmented Mirror
KW - Zero-Expansion Material
UR - http://www.scopus.com/inward/record.url?scp=18144445093&partnerID=8YFLogxK
U2 - 10.1117/12.19228
DO - 10.1117/12.19228
M3 - Conference contribution
SN - 081940280X
SN - 9780819420806
T3 - Proceedings of SPIE - The International Society for Optical Engineering
SP - 586
EP - 596
BT - Advanced Technology Optical Telescopes IV
A2 - Barr, Lawrence D.
PB - SPIE
ER -