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 Physik Instrumente (PI) now extends the range of high-precision positioning of microscope objectives along the optical axis to 2 millimetres (mm) while maintaining short settling times on the order of 20 milliseconds (ms).
Optical metrology, super-resolution microscopy and other techniques require nanometre- and sub-nanometre-level resolution and millisecond response provided by piezo nano-positioning devices. Until now, travel ranges of only a few 100 microns (µm) were available, enough for most microscopy applications. PI’s new drive principle based on the 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.
High-resolution microscopy methods, such as two-photon microscopy, make it possible to record 3D stacks with up to 1mm depth in biological samples. Here, conventional piezo techniques have posed a limitation. PI’s new N-725 piezo-motor objective positioner and scanner makes a break with conventional wisdom and explores new possibilities.
Based on a patented piezo-walk motor, the N-725 provides travel ranges of up to 2mm 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 piezo-focus (PiFoc) objective stages providing travel ranges from 0.1mm to 0.4mm.
The new long-travel piezo motor provides 5 to 20 times the travel range, sub-nanometre resolution and locks into position without further need for power, improving long-term stability. The piezo-z-focus drive comes complete with a motion controller and software. It is also compatible with many microscope imaging-suite software packages.
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