Lightweight active controlled primary mirror technology demonstrator

Year: 2007

Authors: Mazzinghi P., Bratina V., Ferruzzi D., Gambicorti L., Simonetti F., Zuccaro Marchi A., Salinari P., Lisi F., Olivier M., Bursi A., Gallieni D., Biasi R., Pereira J.

Autors Affiliation: CNR – Istituto Nazionale di Ottica Applicata, Largo E. Fermi 6, 50125 Firenze, Italy;
INAF, Arcetri Astrophysics Observatory;
Carlo Gavazzi Space (CGS);
ADS International (ADS);
Microgate (MG);
European Space Agency (ESA)

Abstract: This paper describes the design, manufacturing and test of a ground demonstrator of an innovative technology able to realize lightweight active controlled space-borne telescope mirror. This analysis is particularly devoted to applications for a large aperture space telescope for advanced LIDAR, but it can be used for any lightweight mirror. For a space-borne telescope the mirror weight is a fundamental parameter to be minimized (less than 15 Kg/m2), while maximizing the optical performances (optical quality better than A/3). In order to guarantee these results, the best selected solution is a thin glass primary mirror coupled to a stiff CFRP (Carbon Fiber Reinforced Plastic) panel with a surface active control system. A preliminary design of this lightweight structure highlighted the critical areas that were deeply analyzed by the ground demonstrator: the 1 mm thick mirror survivability on launch and the actuator functional performances with low power consumption. To preserve the mirror glass the Electrostatic Locking technique was developed and is here described. The active optics technique, already widely used for ground based telescopes, consists of a metrology system (wave front sensor, WFS), a control algorithm and a system of actuators to slightly deform the primary mirror and/or displace the secondary, in a closed-loop control system that applies the computed corrections to the mirror

Conference title:

More Information: The authors are grateful to the Europe Space Agency (ESA) for the opportunity offered to develop this research under the contract AO/1-4629/NL/CP. The authors are grateful to the ADS International SRL for pictures of the actuator.
KeyWords: Actuators; Aircraft propulsion; Carbon fibers; Closed loop control systems; Control system analysis; Electric power utilization; Glass; Mirrors; Optical instruments; Optical radar; Optical telescopes; Optical testing; Reinforced plastics; Remote sensing; Space optics; Space telescopes; Technology; Wavefronts, Active optics; CFRP (carbon fiber reinforced plastic); CFRP structures; Closed-loop controls; Control algorithms; Critical areas; Flat mirrors; Flat surfaces; Functional performance; Fundamental parameters; Ground demonstrators; Ground-based telescopes; Innovative technologies; Large apertures; LIDAR; Light-weight mirrors; Light-weight structures; Lightweight optics; Locking techniques; Low-power consumption; Metrology systems; Optical errors; Optical performance; Optical qualities; Power consumption; Preliminary designs; Primary mirrors; Space-borne; Surface actives; Technology demonstrators; Telescope mirrors; Test campaigns; Thin glass; Wavefront sensor, Spacecraft observatories
DOI: 10.1117/12.737839

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