Tip/tilt mirrors are widely used to stabilize astronomical images during integration because tip/tilt image stabilization systems provide a large gain in image quality with a relatively simple control system[KM93,Mc93,0193]. In solar vector magnetographs the polarization analysis section generally precedes the fip/tilt mirror to avoid systematic polarization errors[Ru88,R091]. This causes a magnification of the apparent pointing errors so that the dynamic range requirements for a tip/tilt mirror are multiplied by the magnification. We have used tip/tilt mirrors based on high voltage piezo electric stacks. These units have relatively limited throw of +/- 65 arcsec, and require stack voltages of 0 to 1000 volts. In addition these units displayed a high Q resonance around 200 Hz which limited the stable closed loop image stabilization bandwidth to around 20 to 30 Hz. The tip/tilt system in our ground based instrument at Sacramento Peak Observatory has always been limited by the limited dynamic range of the tip/tilt mirror[St90,St92].
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