From Steppers to Servos: Microscopy Stages at Atomic Resolution

Oxford Instruments Asylum Research is a dominant player in the field of atomic force microscopy (AFM) for materials science, polymers, and semiconductor research. Their latest innovation, the Jupiter Discovery AFM, is a large-sample scanning probe microscope designed to "consistently and easily achieve molecular and even atomic resolution" and deliver scanning rates “5-20x faster than other large-sample AFMs.”

To achieve high-throughput imaging on large samples, the microscope requires a motorized XY stage capable of positioning samples with exceptional stability and precision. Matei Jordache, Product Engineer at Oxford Instruments, led the development of the motion control system for this new platform.

Previous generations of the microscope stage relied on open-loop stepper motor technology. While steppers are a common standard, they often lack the torque density and high-speed precision required for next-generation performance. Additionally, the engineering team wanted to avoid proprietary industrial communication protocols that could result in vendor lock-in.

The team selected Teknic’s ClearPath-SD (Step and Direction) integrated servos. Because these motors accept the same command signals as stepper motors, Oxford Instruments could upgrade to high-performance servos without completely rewriting their control architecture.

"Our old motor stages were XY steppers," says Matei. “Being able to move over to servos and get this huge boost in speed, torque, and accuracy without needing to rework much on the software side was great."

In product development, the speed at which a team can validate a design is critical. The all-in-one nature of the ClearPath system—combining the motor, encoder, and drive electronics—streamlined the physical integration. Combined with Teknic’s Motor Setup Program (MSP), Matei’s team rapidly accelerated their timeline.

"I was able to get a prototype working within a month with our own custom controller and everything," says Matei. "The velocity of that is awesome and super important for product development… ClearPath is just super easy to work with."

Matei highlights the MSP’s software oscilloscope as a high-value tool for visualizing mechanical performance during the design phase. "The software oscilloscope is a really powerful utility for sure."

For an AFM, positioning accuracy is paramount. Unlike the previous open-loop steppers, ClearPath servos strictly monitor position, automatically correcting for disturbances.

"The performance is great. The fact that they’re internally encoded is very nice," says Matei. "You get accurate motion even without external encoders."

With the motion system validated, the Jupiter Discovery AFM is set to deliver higher speed and accuracy to researchers, backed by ClearPath’s robust and flexible servo architecture.