Interferometric Telescopes
Alenia Aerospazio, Italy, designs Mirror Stabilization with PI Piezo Actuators
 
The Global Astrometric Interferometer for Astrophysics (GAIA) is one of ESA's (European Space Agency) cornerstone missions in the Horizon 2000 Plus long-term scientific program. GAIA's objective is to determine star positions and motions with an accuracy of 10 micro-arcsec. This accuracy can only be realized with sophisticated interferometric measurements where distance variations as small as a few picometers between individual opticalcomponents in the interferometer can be detrimental. For nullification of these variations Alenia Aerospazio, Italy, designed an active tip-tilt mechanism based on three PI Piezo Actuators (model P-844.20, Fig.2). The following tests proved the active control system to be capable of ensuring the ultra-high stability requirements fundamental for the achievement of the GAIA mission goals.
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Fig. 1, "Optics Active Controler Experiment" Prototype. Courtesy of Alenia Aerospazio


Fig. 2 Enlargement showing the P-844.20 Piezo Actuator.
Courtesy of Alenia Aerospazio