Abstract
A 25 m four mirror live optics telescope is studied. M1 is
spherical with 141 segments and f/0.96. M1 is reimaged onto M4
also with 141 segments. Image FWHM is <0.1 arc sec over
> 20 arc min. A horseshoe solution with a simple azimuth
platform is applied. M1 segments are supported by a fine meniscus
form truss structure, tied to the horseshoe by a coarser mesh. A
FEM with 10^4 dof was developed and applied. Live optics control
M1 and M4 segments (the latter with potential high bandwidth).
Correction signals in tilt, coma and defocus are traced. A
correlation tracker and a lase guide star system are included. Low
and high wind speed regimes are studied. An end to end simulation
model is developed, based on modal representation of our FEM.
Image quality dependence on wind load is studied from segment
piston and tilt deflections. Eigenmodes are recorded. Using wind
time series, we study dynamic effects and image quality resulting
from the 141 segment spots. Automatic segment control at a
bandwidth of only 1 Hz gives excellent image quality. We foresee
to reach a bandwidth > 50 Hz, securing a system partly
adaptive, with effects of atmospheric wave front tilt removed
through M4 segment tilting at high frequency. Further progress
includes optimization of mechanical design and end-to-end
simulation model, wind tunnel testing and studies of
wavefrontsensor, correlation tracker and instruments. A fully
adaptive system is tentatively studied as is coherent operation at
IR wavelengths.Key words: Very large telescopes - live optics -
image quality - wind buffeting - end-to-end simulation model.
Original language | English |
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Title of host publication | A 25 m Live Optics Telescope |
Place of Publication | Bellingham, Washington, USA |
Publisher | SPIE - The International Society for Optical Engineering |
Publication date | 1996 |
Pages | 585-596 |
Publication status | Published - 1996 |
Event | Optical Telescopes of Today and Tomorrow: Following in the Direction of Tycho Brahe - Landskrona/Hven, Sweden Duration: 29 May 1996 → 2 Jun 1996 |
Conference
Conference | Optical Telescopes of Today and Tomorrow |
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Country/Territory | Sweden |
City | Landskrona/Hven |
Period | 29/05/1996 → 02/06/1996 |