AO optical tolerancing requirements for a segmented active telescope

摘要

Abstract: The University of Mexico 6.5m TIM telescope project has a 19 fully active segmented M1 and an active M2. Each 1.8m segment is a relative thin meniscus supported by three position hard points, computer controlled, and 16 force soft actuators which support the meniscus and can deform it. This project includes an AO system using a corrector mirror placed at a conjugated telescope pupil. We decided to specify the telescope optics in function of this AO system from the beginning and not specify the AO system in function of the telescope. In order to calculate the optical budget of the TIM we simulated, using a Monte Carlo technique e approach, the Strehl ratio of the telescope PSF as a function of the low order aberration values of the individual segments. The low order aberrations studied are the 'position' aberrations, as the piston and the tip-tilt between the segments, and the 'deformation' aberrations as the values for the deformation aberrations for each segment are comparable with the 'intrinsic' quality of the primary mirror of an active telescope as the NTT or our recently enhanced 2.1m UNAM telescope, if diffraction limited imaging for the complete primary is specified. This result shows that the technology for a correct support for the individual segments actually exist. The results obtained are used for the optical quality definition of the TIM 6.5m telescope. !19