In high-precision optical-lens and semiconductor chip manufacturing, a positioning error of just a few microns can scrap an entire part. The resolution required is at the nanometer scale (1 nanometer = one-millionth of a millimeter) — beyond the reach of ordinary screw- or rotary-motor drives. The component that delivers this resolution is the piezo actuator.
What is piezo, and how does it work?
Piezo comes from the piezoelectric effect: when a voltage is applied to a special ceramic material, it changes shape (expands or contracts) by an extremely fine, precisely controllable amount. This deformation is driven directly by the electric field — no gears, no screws, no rubbing parts — so it can move with sub-nanometer resolution and respond very fast.
How it works, step by step
Inside a piezo ceramic, the crystal lattice contains tiny electric dipoles. The effect works both ways: squeeze the crystal and it produces charge (the direct effect, used for sensors); conversely, apply a voltage and the crystal moves (the inverse/converse effect — the basis of piezo actuators).
- Apply a voltage → an electric field forms across the ceramic.
- The dipoles in the crystal realign with the field, so the crystal stretches/contracts slightly.
- A single layer’s expansion is tiny, so many layers are stacked to add up into usable travel.
- Displacement scales nearly linearly with voltage → nanometer positioning is set by tuning the voltage.
- Closed-loop models add a feedback sensor to correct hysteresis and drift for accurate, stable position.
Note: open-loop piezo exhibits hysteresis (the up and down voltage curves give slightly different positions) and creep over time, so accuracy-critical jobs should use closed-loop models with an integrated position sensor.
Why piezo suits nanopositioning
- Sub-nanometer resolution — far finer steps than screw or stepper systems.
- No backlash and no friction — driven directly by the field, so position is stable and highly repeatable.
- Fast response and high stiffness — short settling time, ideal for high-throughput fine moves.
- Short but extremely accurate travel — typically microns to a few hundred microns.
- Virtually maintenance-free and clean — no wearing parts, suited to cleanrooms.
The specs that matter
| Spec | What it means |
|---|---|
| Resolution | The smallest controllable step — piezo reaches sub-nanometer. |
| Travel range | Total travel, usually short (microns–hundreds of microns) traded for fine resolution. |
| Closed-loop vs open-loop | Closed-loop (with feedback) gives better accuracy and stability for metrology/alignment. |
| Axes (1–6) | From single-axis to 6-axis hexapods for combined angular + positional alignment. |
How it is used in lens and semiconductor manufacturing
- Optical/fiber alignment to nanometer-level centering for maximum optical quality.
- Lens-surface metrology that needs a fine, stable scanning motion of the probe.
- Wafer inspection and mask alignment in lithography.
- Active vibration/drift compensation to hold position steady during a process.
- Micro-assembly and precision dispensing that demand high repeatability.
Piezo & nanopositioning systems from Physik Instrumente (PI)
Physik Instrumente (PI) of Germany is a world leader in high-precision positioning and piezo technology — covering resolution down to 1 nm and below, travel from microns up to 1000 mm, and up to 6 axes (hexapods) — so you can match the system precisely to lens and semiconductor work.
| PI series | Strength | Best for |
|---|---|---|
| Piezo Nanopositioning Stages | Friction-free XY/XYZ flexure stages, sub-nanometer resolution | Lens alignment, microscopy, and metrology |
| Hexapods | 6-axis parallel-kinematic positioning, highly repeatable | Combined angular + positional alignment (optics/photonics) |
| PIglide Air-Bearing & Linear-Motor Stages | Frictionless air bearings, high speed, vibration-free | Wafer scanning/inspection in semiconductor |
| Motion Controllers | Command piezo, hexapod, and air-bearing in Cartesian coordinates | Unifying multi-axis control in one system |
Piezo vs ordinary motors
Screw, stepper, and servo systems are great for long travel and general motion, but hit a ceiling at backlash, friction, and micron-level resolution. When the job needs nanometer precision, piezo is the answer — and in practice they are often combined: a motor handles the coarse approach, then piezo does the final fine tuning (a coarse/fine stage).
PMC Technology distributes piezo and nanopositioning systems from leading makers such as Physik Instrumente (PI), Nanomotion, and Aerotech, and can analyze your application to recommend the right model for your resolution, travel, and axis-count needs.
