A-311 Line of Low-Profile Planar XY Air Bearing Stages

PI adds to its compact A-311 line of low-profile planar XY air bearing stages. PI’s U.S.-based air bearing R&D and manufacturing teams have created two new versions with travel ranges of 200mm x 200mm and 300mm x 300mm. Planar scanning stages are suitable for semiconductor inspection, laser marking, optical metrology and other precision motion applications.

The compact A-311 air bearing planar series uses a hardcoat aluminum base and two motors, reducing size, weight and cost compared to traditional granite based planar XY stages. Excellent motion fidelity is achieved, for example 1µm straightness over 300mm (and 10nm per 10mm) and 10µrad orthogonality over 300mm. Integrated absolute measuring linear encoders provide:

• 1nm resolution
• 0.1µm bidirectional repeatability
• 0.2µm accuracy

The stages are controlled by a high performance, EtherCat-based motion controller with advanced features such as ServoBoost and NanoPWM for higher resolution and adaptability to a wider load range.

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, along with pitch/yaw/roll, are significantly better than with conventional mechanical bearings. Requiring no maintenance or lubrication, air bearings are ideal for use in clean rooms.


Smooth motion with no cogging is provided by ironless linear motors; position information down to 1nm resolution comes from the integrated absolute linear encoders. Features and advantages include:

• Velocities up to 2m/sec
• Acceleration to 2.75g
• Load capacity is increased to 147N (~30lb)
• Cleanroom compatibility

The planar XY stages can be combined with air bearing rotary stages for 3-axis, XY-Theta-Z motion applications. PI’s rotary air bearing stages are available with diameters from 50mm to 300mm and provide excellent motion properties with eccentricity down to 75nm and wobble down to 1µrad. Low profile, Z/tip-tilt options are also available.