PI’s New Z-Axis Optical Axis Nanopositioning System Offers 5X more Travel

High precision positioning of microscope objectives along the optical axis has just made a giant leap forward: While piezo actuation has always been the undisputed 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 2 mm while maintaining very short settling times on the order of 20 milliseconds.

Applications
Optical metrology, super-resolution microscopy and other techniques require the nanometer and sub-nanometer level resolution and millisecond response provided by piezo nanopositioning 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 coordinated motion of multiple piezo elements overcomes these limitations. Deep penetration microscopy methods, such as two-photon microscopy, benefit from the new piezo positioning device.

3D-Imaging
High resolution microscopy methods, such as two-photon microscopy, make it possible to record 3D stacks with up to 1 mm depth in biological samples. Here conventional piezo techniques have posed a limitation. PI’s N-725 piezo-motor objective positioner and scanner breaks with conventional wisdom and helps exploit the new possibilities.

Patented PiezoWalk Motor
Based on a patented piezowalk motor, the N-725 provides travel ranges of up to 2 mm along the optical axis to quickly and precisely change the focal plane. 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 0.4 mm. 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.

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