Measurements and analysis of induced vibrations in optical telescopes

Optical telescopes are the most intriguing investigative instruments used for astrometric monitoring and for investigation of celestial objects. Literature presents several investigations concerning the expected imaging performance of optical telescopes and sources of influence which can affect the obtained image quality. In fact its features can drastically decrease in presence of induced vibrations, kinetic movements and mechanical shock, which can come from external sources (i.e. ambient disturbance) or internal signals (i.e. working conditions of the telescope). It should be noted that in the perspective to predict vibrations level which could affect the device, several solutions have been proposed in literature by using wind-tunnel tests (to emulate ambient effects), fluid-dynamic analysis, simulations, shock test, etc. However, very often, these methods implies approximations in terms of induced vibrations as respect the real scenario. In this context, we present here measurements campaigns to study the real kinetic influences which affect a telescope and to analyze the most critical points where these movements are applied. The analyses here conducted arouse interest during the design and the mounting of the instrument and also in order to design specific active compensations, mechanical filters, feedback control and helpful for real-time vibration corrections. In the present study, several types of induced movements will be accounted through 3D measurements and considerations in terms of impressed accelerations.