25-m Live Optics Telescope

Arne L. Ardeberg; Torben Andersen; Mette Owner-Petersen; Niels-Christian Jessen

doi:10.1117/12.269085

21 March 1997 25-m Live Optics Telescope

Arne L. Ardeberg, Torben Andersen, Mette Owner-Petersen, Niels-Christian Jessen

Proceedings Volume 2871, Optical Telescopes of Today and Tomorrow; (1997) https://doi.org/10.1117/12.269085
Event: Optical Telescopes of Today and Tomorrow, 1996, Landskrona/Hven, Sweden

Abstract

A 25 m four mirror live optics telescope is studied. M1 is spherical with 141 segments and f/0.96. M1 is re-imaged onto M4, also with 141 segments. Image FWHM is less than 0.10 arc sec over greater than 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 horseshoes by a coarser mesh. A FEM with 10⁴ dof was developed and applied. Live optics control M1 and M4 segments (the latter with potentially high bandwidth), M1/M4 segment balancing and servos. Correction signals in tilt, coma and defocus are traced. A correlation tracker and a laser 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 greater than 50 Hz, securing a system partly adaptive, with effects of atmospheric wave front tilt removed through M4 segment tilting at high frequency. Further progress include optimization of mechanical design and end-to-end simulation model, wind tunnel testing and studies of wave front sensor, correlation tracker and instruments. A fully adaptive system is tentatively studied as is coherent operation at IR wavelengths.

Citation Download Citation

Arne L. Ardeberg, Torben Andersen, Mette Owner-Petersen, and Niels-Christian Jessen "25-m Live Optics Telescope", Proc. SPIE 2871, Optical Telescopes of Today and Tomorrow, (21 March 1997); https://doi.org/10.1117/12.269085

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