摘要：Context. Segmented primary mirrors are indispensable to master the
steady increase in spatial resolution. Phasing optics systems must reduce segment
misalignments to guarantee the high optical quality required for astronomical science
programs.
Aims. Modern telescopes routinely use adaptive optics systems to
compensate for the atmosphere and use laser-guide-stars to create artificial stars as
bright references in the field of observation. Because multiple laser-guide-star adaptive
optics are being implemented in all major observatories, we propose to use man-made stars
not only for adaptive optics, but for phasing optics.
Methods. We propose a method called the doublet-wavelength coherence
technique (DWCT), exploiting the D lines of sodium in the mesosphere using laser
guide-stars. The signal coherence properties are then used.
Results. The DWCT capture range exceeds current abilities by a factor of
100. It represents a change in paradigm by improving the phasing optics capture range from
micrometric to millimetric. It thereby potentially eliminates the need of a man-made
mechanical pre-phasing step.
Conclusions. Extremely large telescopes require hundreds of segments,
several of which need to be substituted on a daily basis to be recoated. The DWCT relaxes
mechanical integration requirements and speeds up integration and re-integration
process.
关键词：instrumentation: adaptive optics;instrumentation: high angular resolution;methods: analytical;techniques: high angular resolution;telescopes;methods: numerical
