Magnetically levitated XY-THETA motion stage for X-ray microscopy applications

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Fahmy, Abdel

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Precision motion systems with micro/nanometers accuracy are used in a wide range of applications such as semiconductor metrology inspection equipment and photo lithography scanners, precision machine tools and microscopes. The demand for precision motion systems that offer higher precision positioning performance and faster motion acceleration in more degrees-of-freedom (DOFs) and can offer a compact design necessitates more sophisticated precision motion systems. In this thesis, we present the modeling, design, prototyping and experimental evaluation for a magnetically levitated positioning stage with a novel electromagnetic design that uses the concept of a bearing-less motor. The developed stage is to be used for microscope applications, the stage can move in 5-DOFs and provide approximately 12mm range of motion in the X-Y-DOFs and full 360 degrees of rotation around the vertical axis, we also present how this stage can be upgraded to provide motion in all 6-DOFs with the integration of a Voice Coil Actuator (VCL).

The prototype stage has been successfully levitated and the position control loop experimentally demonstrated a bandwidth of 32 Hz. These results show that the proposed stage is able to meet the needed requirements for precision stages of microscope applications that offer high speed long range scanning and have a compact design. The initial results show promise that with an upgraded sensing system and further tuning of the controller, the proposed stage can offer nanometer positioning accuracy and longer range of motion.


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