PI Planar XY Air Bearing Stage Provides Better Motion Fidelity

Why Use Planar Air Bearings in Precision Positioning Equipment? Air bearing positioners float on air to provide completely frictionless motion, resulting in negligible hysteresis or reversal error, excellent velocity stability, and zero-wear of mechanical components. Due to the surface averaging effect, straightness and flatness are significantly better than with conventional mechanical bearings. Planar stages further improve the performance because all motion on the XY axes is defined by the precisely ground granite surface. Unlike stacks of individual single-axis stages, with a planar stage, no bending moments are introduced when the load on the Y stage moves off-center.

Special Preloading Improves Stage Performance

The PIglide HS uses magnetically preloaded air-bearings on the Y axes, and a vacuum preloaded X-Y puck that floats on the reference surface. The cross-beam mounts to the Y axis via a highly engineered flexural coupling that provides yaw-compliance without sacrificing system stiffness.

H-Bridge Design with Active Yaw Control

The gantry axis is a dual air-bearing H-bridge design that incorporates dual linear motors and dual linear encoders. This improves turnaround performance while providing the added benefit of orthogonality/yaw/straightness control. Ironless linear motors provide smooth motion and no cogging or attractive forces.  

Both incremental and absolute encoder options are available. The PIglide HS incorporates three high-accuracy linear encoders, one for the bridge axis and two for the gantry axis. Each encoder is mounted so that the scale centerline is as close to the working plane as possible to reduce Abbe errors.

Advanced Control Algorithms

The PIglide HS is coupled with industry-leading digital controls that offer superior servo update rates (up to 5 kHz), advanced control algorithms to improve dynamic performance and error compensation, and a wide suite of software development tools.

Applications of the HS Planar

Metrology, wafer inspection and scribing applications, ultra-precision motion application, such as flat panel inspection.

Features & Advantages

• Active yaw and straightness compensation provides superior straightness of motion
• Travels up to 500mm x 1000mm
• Advanced servo algorithms for optimum stability, move and settle, and scanning performance
• Absolute linear encoders available