PI introduces A-688 air-bearing rotary stage for precision motion

PI, a provider of precision motion control and air bearing motion systems, has introduced the A-688 rotary stage, a motorized, air-bearing rotation stage designed for high-precision, frictionless motion and long-term reliability in metrology, optics, photonics and semiconductor applications.

Built with a frictionless air-bearing design, the A-688 rotation stage provides high accuracy, stability, and durability. Its 260 mm clear aperture allows optical beams, cables, or mechanical components to pass through the center, making it suitable for interferometry, precision inspection and beamline applications. The non-contact design minimizes wear and backlash and operates without lubrication, supporting clean and smooth motion in cleanroom or vacuum environments.

The rotation stage uses a direct-drive, ironless torque motor that provides smooth, cog-free rotation with fast acceleration and precise velocity control. When paired with high-resolution encoder feedback—available in incremental or absolute versions—the system delivers angular resolution down to 0.0015 µrad and minimizes wobble, tilt, and runout errors. These features enable accurate and repeatable angular positioning and continuous scanning at nanoradian precision.

Key highlights and capabilities

• Large clear aperture: Ø 260 mm allows substantial optical or mechanical payloads to pass through or be integrated in the rotation axis
• High resolution and accuracy: Up to 0.0015 µrad angular sensor resolution (in the B100 variant with absolute encoder)
• High-speed performance: Maximum angular speeds of up to 500 rpm
• Precision geometry:
  • Radial error ≤ ±0.15 µm
  • Axial error ≤ ±0.175 µm
  • Wobble (tilt error) < 1 µrad
• Direct-drive motor: Ironless 3-phase motor delivers smooth, backlash-free motion
• Encoder options: Available with incremental (sin/cos) or absolute (BiSS-C) encoders for accurate closed-loop feedback and immediate referencing
• Air bearing design: Frictionless operation eliminates mechanical wear and the need for lubrication or maintenance
• Flexible installation: Operates in horizontal, vertical, or inverted orientations and supports various mounting configurations
• Operational modes: Configurable for point-to-point indexing or continuous scanning based on application requirements

Applications and market impact

The A-688 is designed for systems that require high-precision rotation, such as:

• Optical alignment, beamline systems, interferometry and metrology
• Semiconductor wafer inspection, lithography and mask alignment
• Calibration, scanning and inspection systems
• Tomography and imaging platforms
• Cleanroom, vacuum or contamination-sensitive environments (due to frictionless motion)

Because the A-688’s air bearing generates no particulate contamination, it is suitable for cleanroom and optical applications.

Availability and support

The A-688 will be available in multiple variants (e.g. A-688.A100 with incremental encoder, A-688.B100 with absolute encoder) to suit a range of application needs.

Comprehensive documentation, datasheets, 3D models and integration support will accompany the product. Customers can also consult with PI engineers for custom adaptations or multi-axis configurations.

For more information, visit pi-usa.us.