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Lego Figure holding a lego telescope. Photo

Arne Ardeberg

Professor emeritus

Lego Figure holding a lego telescope. Photo



  • Torben Andersen
  • Arne Ardeberg
  • J Beckers
  • Alexander Gontcharov
  • Mette Owner-Petersen
  • Holger Riewaldt


  • Arne Ardeberg
  • Torben Andersen

Summary, in English

The Euro50 is a telescope for optical and infrared wavelengths. It has an aspherical primary mirror with a size of 50 meters and 618 segments. The optical configuration is of Gregorian type and the secondary mirror is deformable for adaptive optics. Observations can take place in prime focus, Gregorian foci, and Nasmyth foci using additional relay mirrors. The telescope provides seeing limited observations, partial adaptive optics with ground layer correction, single conjugate adaptive optics and dual-conjugate adaptive optics. For prime focus observations, a clam-shell corrector with a doublet lens is used. The primary mirror segments can be polished using the precessions polishing technique. "Live Optics" denotes the joint segment alignment system, secondary mirror control system, adaptive optics and main axes servos. An overview is given of the live optics architecture, including feedback from wavefront sensors for natural and laser guide stars, and from primary mirror segment edge sensors. A straw man concept of the laser guide star system using sum-frequency YAG lasers is presented together with a solution to the laser guide star perspective elongation problem. The structural design involves a large steel structure and a tripod of carbon fiber reinforced polymer to support the secondary mirror. Integrated models have been set up to simulate telescope performance. Results show that an enclosure is needed to protect the telescope against wind during observations. The enclosure is very large box-shaped steel structure


  • Lund Observatory - Has been reorganised

Publishing year







Proceedings of the SPIE - The International Society for Optical Engineering





Document type

Conference paper




  • Astronomy, Astrophysics and Cosmology


  • optical wavelength telescope
  • infrared wavelength telescope
  • aspherical primary mirror
  • Gregorian type optical configuration
  • Nasmyth foci
  • Gregorian foci
  • relay mirrors
  • single conjugate adaptive optics
  • dual conjugate adaptive optics
  • ground layer correction
  • clam shell corrector
  • precessions polishing technique
  • joint segment alignment system
  • wavefront sensors
  • secondary mirror control system
  • main axes servos
  • natural guide stars
  • 50 m
  • primary mirror segment edge sensors
  • laser guide stars
  • wind protection
  • carbon fiber reinforced polymer
  • perspective elongation problem
  • box-shaped steel structure
  • live optics architecture
  • sum frequency YAG lasers
  • straw man concept
  • Euro50 telescope

Conference name

Second Bäckaskog Workshop on Extremely Large Telescopes, 2003

Conference date

2003-09-09 - 2003-09-11

Conference place

Bäckaskog Castle, Sweden




  • ISSN: 0277-786X
  • ISSN: 1996-756X