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S.W. Teare, D. Lamppa, K. Sugimoto, J. Yates, H. Xiao (New Mexico Tech), L.A. Thompson (University of Illinois at Urbana-Champaign)
An image stabilization system is commonly used on astronomical telescopes to compensate for poor mount performance, low-order effects from atmospheric seeing and local index of refraction instabilities near the telescope. An image stabilizer is comprised of an electro-optical component and a sensor that are used in concert to lock the position of a wavefront or image centroid onto a camera. There are several commercial tip-tilt and sensing systems and components that can be used for image stabilization depending on the user’s performance and cost requirements.
We report on an inexpensive image stabilizer for use on astronomical telescopes developed as part of the NSF funded (AST-00-96741) UnISIS laser guide-star project at the Mount Wilson Observatory. The instrument uses inexpensive, commercial-off-the-shelf (COTS) components for beam steering, position sensing and the processor/control system. The limiting magnitude of the system depends on the properties of the light sensor used.
The image stabilizer operates as a turnkey system with 2 main control modes to provide different performance capabilities for different operating conditions. The normal mode uses a proportional, integrating, differentiating (PID) controller and the second mode uses a more complex fuzzy logic based control scheme. We have examined other control methods and continue to experiment with different schemes. The simplicity of the system allows for many different control models to be implemented and evaluated in the laboratory and on the telescope. This flexibility and low cost provides an inexpensive system that can be used for both image stabilization and monitoring of the astronomical seeing at an observing site. Such systems are also invaluable for introducing astronomy students to instrumentation and engineering students to the innovative control aspects of telescope systems.
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.