A theoretical and experimental study of the dynamic response of high precision optical positioning systems

At the Advanced Photon Source (APS), a state of the art synchrotron radiation facility at Argonne National Laboratory (ANL), high precision optical positioning systems are needed to conduct a wide range of experiments utilizing the high brilliance x-ray beam. The high precision, multi dimensional positioning stability required for these positioning systems may be compromised by low-level, low frequency vibrations traveling through the ground and/or vibrations caused by flow-structure interactions in the cooling systems. As a consequence, the design and manufacture of these systems requires special care to achieve the required high performance and functional specifications. Having an accurate computer model makes it possible to simulate the dynamic behavior before physically assembling the system. At the same time, the proposed system design can be validated and optimized during the initial stages in a very cost effective way.;In order to predict the dynamic response of these positioning systems, a linearized multibody formulation has been developed. The proposed methodology has been applied to specific example cases, an optical table and a mirror support system used at the experimental stations of APS. The experimental studies conducted on both systems throughout the study illustrated the crucial importance of the kinematic joints and components that comprise these multibody structures. Improved experimental and theoretical methods have been introduced to estimate the dynamic properties of these components. Linear and rotational bearings, and high precision positioning stages are analyzed experimentally and theoretically to characterize their stiffness properties. These improved models are incorporated into system equations to predict the natural frequencies and mode shapes of the positioning systems.;The results obtained by theory compare well with the experimental findings. The proposed methodology is precise and generic in predicting the dynamic response of the positioning systems. It is easily adaptable to similar systems at APS and similar facilities. The coupled multi dimensional, multi degree of freedom vibratory motion at resonance frequencies can be simulated and observed visually for the given positioning configurations. The developed model can also be used to simulate the vibratory response under the effect of vibratory excitations seen in day-to-day use.