N-725 Optical Axis Nano-positioning System

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The N-725 Z-axis positioner and optical axis nano-positioning system offers five times more travel range for high-resolution microscopes and surface metrology.

While piezo actuation has always been the choice in optical positioning when dynamics and accuracy matter most, some applications could have benefitted from more travel range. A new design principle developed by PI (Physik Instrumente) now extends the positioning range to 2mm while maintaining very short settling times on the order of 20 milliseconds.

Optical metrology, super-resolution microscopy, and other techniques require the nanometre and sub-nanometre level resolution and millisecond response provided by piezo nano-positioning devices. Until now, travel ranges of a few 100 microns were available, enough for most microscopy applications. PI’s new drive principle based on a co-ordinated motion of multiple piezo elements overcomes these limitations.  Deep penetration microscopy methods, such as two-photon microscopy benefit from the new device.

Based on a patented piezowalk motor, the N-725 provides travel ranges of up to 2mm along the optical axis to change the focal plane quickly and precisely. Despite its small size, the new device replaces and combines the performance of two individual stages: a fine focus piezo drive and a stepper motor positioner for coarse, long travel motion. The challenge was to implement the high-stiffness piezo motor in a compact mechanical housing no larger than PI’s previous piezo-flexure-actuator based PIFOC objective stages providing travel ranges from 0.1 to 0.4mm. The new long-travel piezo motor provides 5 to 20 times the travel range, sub-nanometer resolution and locks into a position, without further need for power, significantly improving long-term stability.

The piezo-z-focus drive comes complete with a powerful motion controller and software. It is compatible with leading microscope imaging suite software packages.