Technical Features; Air Bearing; Torque Motor; Encoder - PI A-62 Series User Manual

User Manual
A620D0001 Rev 1.2
30-July-2019
4.

Technical Features

4.1.

Air Bearing

The A-62x series stage features fully preloaded, non-contact, frictionless air bearings to guide the motion of the
stage and support the payload. This air bearing is a highly accurate precision instrument. The non-contact
nature of the air bearings will provide years of accurate and reliable use if treated properly. Keep the bearing
clean and avoid any shocks, drops or bumps that can cause scratches, dings or distortion of the bearing.
The A-62x incorporates opposing axial and radial preload mechanisms. This sort of preload makes the A-62x
suitable for various mounting orientations, such as horizontal, vertical, and inverted. Be careful not to apply
excess cantilever loads to the stage table.
4.2.

Torque Motor

The A-62x series stage features a brushless, ironless, slotless 3-phase torque motor. This type of motor
technology is completely non-contact and is ideally suited to high speeds; high accelerations; fine resolution
positioning; and smooth, constant-velocity scanning. The motor must be commutated by an external motor drive.
Hall Effect sensors are not included, so the drive and/or controller must be capable of encoder-based (sine)
commutation.
4.3.

Encoder

The A-62x series stage features an optical non-contact position encoder for direct measurement of the stage
position. This feedback signal is used by an external motion controller to close the servo loop for position and
velocity control.
The A-62x series stage offers two types of encoders:

Incremental with analog (sine) output: Suitable for use with controllers using on-board encoder interpolation.

Absolute with BiSS-C 32-bit serial output: Eliminates the need for startup homing routines and limit switches.
4.4.

Index Mark (Incremental encoders only)

When equipped with either of the incremental encoder options, the A-62x series stage features a non-contact
home index marker. The index is integral to the encoder electronics. The index mark is optical; there is one
index per revolution of the stage.
PI (Physik Instrumente) L.P.
16 Albert Street, Auburn, MA 01501
Tel: 508-832-3456 Fax: 508-832-0506
Email: air@pi-usa.us
Page 13 of 32