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Large Piezo Tilt Platforms for Astronomical
Applications

• Active Secondary Mirror Stabilization
  
• Mirror Diameters to 300 mm
  
• Integrated Momentum Compensation

During the last decade, PI has designed several large aperture tip/tilt systems for image stabilization. Resolution in large earthbound telescopes is limited by atmospheric turbulence which causes shifting images. Piezoelectrically driven, active secondary mirrors significantly improve telescope resolution during long integrations by correcting for these image shifts in real time.

Due to the inertia of the large mirrors and the fast acceleration required to correct for image fluctuations, significant forces can be induced in the telescope structure causing unwanted vibrations.

To cancel these forces before they excite vibrations in the telescope structure, PI has developed momentum compensation systems integrated into the tip/tilt platforms. Any vibration caused by the motion of the mirror is canceled with an efficiency up to 95% by the internal, piezoelectrically driven momentum compensation device.

PI also offers Six-Degree-of-Freedom Hexapod Systems for tip/tilt platform alignment.

Subaru Telescope (under construction), Keck I and Keck II Observations and NASA IRTF Telescope (silver dome), Mauna Kea, Hawaii

Active secondary tip/tilt mirror for the European Southern Observatory's 2.2 m telescope in La Silla, Chile. Mirror diameter: 100 mm Tip/tilt range: ± 400 µrad Resonant frequency: 900 Hz

Active secondary tip/tilt platform for IRTF (Mauna Kea, Hawaii) with Hexapod 6-Degrees-Of-Freedom alignment system. Mirror diameter: 244 mm Tip/tilt range: ± 250 µrad Resonant frequency: 490 Hz

Active tip/tilt platform for Subaru Telescope (Mauna Kea, Hawaii). Mirror diameter: 150 mm Tip/tilt range: ± 600 µrad Resonant frequency: 610 Hz

Active secondary tip/tilt platform for UKIRT (Mauna Kea, Hawaii) with Hexapod 6-Degrees-Of-Freedom alignment system. Mirror diameter: 314 mm Tip/tilt range: ± 500 µrad Resonant frequency: 280 Hz

The figures below are from: Progress Report on DISCO: A Project for Image Stabilization at the 2.2 m Telescope, F. Maaswinkel, S. D'Odorico and G. Huster, ESO, F. Bortoletto, Istituto di Astronomia, University di Padova, Italy. Image stabilization with Active Secondary Mirror (courtesy of ESO)

Telescope Structure with Active Secondary Mirror (courtesy of ESO)