Acoustic levitation is an attractive and versatile technique that offers several advantages in terms of particle size, range, reconfigurability, and ease of use with respect to alternative levitating techniques. In this paper, we study the use of active damping to improve the response time and positioning precision of an acoustic levitator operating in air. We use a laser Doppler vibrometer to measure the velocity of a levitated particle. Using this information, a control algorithm is designed and implemented to provide active damping. By system identification and modeling, we demonstrate that the active damper mechanism is well-predictable by models and can be electronically reconfigured and controlled.

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This paper discusses a 6DoF positioning system that utilizes a thin air film to directly position flat substrates with sub-micrometer precision. Such a position system can be applied in the production of electronic devices, such as integrated circuits, flat panel displays and solar cells. All these devices are manufactured on a flat base substrate, e.g. a silicon wafer or glass plate. Precision positioning stages are used during exposure, inspection, alignment, etc. We present a planar positioning system where only the product mass is driven and without mechanical contact. This system has two main advantages: a moving mass of 2 to 3 orders of magnitude smaller, since the carrier stage is eliminated and the absence of mechanical contact reduces the chance of contamination or damage.@en