Sierramotion Products

Linear Actuator with Moving Magnet and Air Bearing


Many optics and photonics applications require linear limited travel fine motion with high precision. Redirecting laser beams requires near perfect travel without any runout in X and Y directions while travelling in the Z direction. This precision stage uses moving magnet linear motor technology to apply force in the Z direction. When coupled to a linear absolute encoder positioning and precision can be realized in the nanometer resolution range.  The Air Bearing helps to stabilize the motion and eliminate nearly all unwanted travel in X and Y.

Precision Movement

With a high-resolution linear encoder, movements as small as 50 nanometres can be achieved. Controlled by a high response servo controller this actuator can even adjust for changes in mechanical parts due to heat rise.

Linear force control zero cogging force

The linear motor can achieve linear force sensitivity with current, eliminating saturation. This air core magnetic technology also offers zero cogging for smooth operation.

Long Life

With linear motor coils stationary and magnets moving, the life of the device is near infinite. The Air Bearing has very long life due to non-contacting parts. The motor doesn’t add any life limiting contact.

Options mechanical mounting and interfaces

The common parts for this actuator are limited to the Air Bearing. All other mechanical parts can be modified and adjusted to mount into customer mechanical parts.

Low Weight

The linear motor components are highly integrated with the air bearing. Travel is restricted to the motion achieved by the Air Bearing and very little extra length is required for the linear motor. The moving inertia is very low compared to other systems using voice coil actuators mounted at the rear of the air bearing.

Precision force control

Direct drive linear motors have proven to provide high response and high stiffness. Both of which can be used in providing high resolution force control and precision positioning. With a constant load, like a lens, the motion profiles can be predetermined with a state space controller to optimize and provide repeatable motion.

linear Actuator Specifications

Precision movement, smooth motion, high resolution, and long life are all critical outputs of this system.

High Torque/Weight 6 Newtons/amp force constant from two wire limited travel linear motor.
Precision Movement Linear motion in Z with X and Y runout less than 1 micron.
Accuracy 1 micron accuracy depending on the travel and encoder scale chosen.
Voltage options 24-48 volt standard operation.
Optional motor windings Adjust the internal force to match the driver current, voltage and speed required.
Package Size 75mm X 75mm X 75mm overall package size. Optional holder for mirror/optics insert.
Customization Sierramotion is willing and interesting in customizing this assembly to meet mechanical, electrical, and control needs.
Wide speed range at output 100 mm/sec output speeds, depending on the resolution chosen and voltage available.

Discuss your actuator requirements with an engineer today .