EXFO is a global leader in the design, manufacture, and marketing of light-based delivery systems. Our focus is within the following market applications:

Positioning Technology

Piezoelectric (PZT) technology serves as the foundation for EXFO's line of precision positioning products. This PZT technology, combined with proprietary precision stages, high-resolution position encoders, and low-noise drive electronics, allows EXFO to offer a variety of capabilities for precise motion control.

A PZT actuator is an electro-mechanical device that undergoes a dimensional change when voltage is applied. The result is nanometer resolution movements over small distances on the order of micrometers. Dimensional changes are proportional to the applied voltage and therefore can be adjusted with extremely high resolution.

The maximum dimensional change of a PZT actuator is on the order of 0.1% of its total length resulting in a range of travel that is limited to tens of micrometers. Since most applications require a larger range of travel, considerable design and manufacturing expertise is required to use PZT actuators as useful positioning devices. EXFO has developed a unique line of PZT-based products that provide the high-resolution movement associated with PZT material, but over a larger, more useful travel range.

The EXFO Technology Advantage

Burleigh®'s products expand the range of PZT actuators without compromising precision, stiffness or stability. For approximately 30 years, our piezoelectric stepping motor has been commercially available and has been routinely used in precision positioning systems that achieve nanometer resolution, movement range greater than 100 millimeters, push force greater than 15 Newtons (N), speed greater than 1.5 mm/second, stiffness greater than 1 N per micrometer and inherent vacuum and non-magnetic compatibility.

While other positioning technologies are limited by backlash and low stiffness, EXFO's PZT-based products are uniquely suited for integration with the latest glass-scale encoder technology. Simple servo algorithms maintain EXFO stages at the desired position and the motor's high stiffness minimizes sensitivity to factory disturbances. Further, as a result of the bi-directional repeatability present in our products, peak finding procedures are simplified and Photonics alignment takes less time. Additionally, any commanded position can be maintained with zero heat dissipation and minimal drift, and the aligned coordinates can be maintained, without dithering, while fixing the pars with adhesive or laser welding.

As a result of EXFO's unique technical and manufacturing competencies, we have developed multiple PZT-based products that maintain several key competitive advantages, including:

• Smooth Output Motion: The "stepping" action of motors is inherently discontinuous as various components must move and stop throughout the operating cycle. In addition, clamps are never "perfect", due to mechanical cross coupling, and axial movement is created with the clamps are turned on and off. The design of EXFO's products, however, overcomes these limitations and achieves nearly smooth motion by careful design and integration of the extension actuator and clamping mechanisms.
• Longevity: EXFO's positioning products, as all other PZT-products, involve friction drives with PZT actuated clamps, and are affected by wear and fatigue issues. However, due to its extensive experience with designing and manufacturing clamps, EXFO ensures that the tribology of the clamp material and the shaft material are specifically selected and processed and that the factory fit is maintained throughout the life of the motor. The PZT clamp material is further specified and tested to have maximum strength and no cracks, with can lead to premature fatigue failures. As a result, the wear on EXFO's products is minimized and field life is maximized.
• Precision Drive and Control Instrumentation: Optimum motor performance requires high performance drive and control instrumentation. EXFO's electronic controllers optimally drive its motor products using three independent high-voltage channels. The three driving waveforms work together with microsecond synchronization to control the PZT actuators with negligible noise and cross talk. At the same time these controllers are designed to maximize motor life by preventing the voltages, currents and shaft positions from exceeding safe limits. Finally, EXFO's electronic controllers provide closed-loop position control and interfaces for remote host computer control to enable multi-axis robotic systems.
• Nanometer Resolution Closed-Loop Control: The high resolution, high stiffness, zero backlash and small size of the EXFO's products makes them uniquely suited for integration with the newest commercial position encoders.