Serial Metrology: One sensor is assigned to eachdegree of freedom to be servo-con-trolled. Undesired off-axis motion(guiding error) from other axes in the direction of a given sensor, go unrecognized and uncorrected (see also “Parallel Metrology”). Stiffness: Spring constant (for piezoelectricmaterials, not linear).

Piezoelectric transducer, piezoelectric actuator

Glossary

Parallel Metrology: Unlike in serial metrology designs,each sensor measures the position of the same moving platform in the respective degree of freedom. This keeps the off-axis runout of allactuators inside the servo-controlloop and allows it to be corrected automatically (active guidance). Piezoelectric Materials: Materials that change their dimen-sions when a voltage is applied and produce a charge when pres- sure is applied. Poling / Polarization: Trajectory-Control: The procedure by which the bulkmaterial is made to take on piezo- electric properties, i.e. the electricalalignment of the unit cells in a pie-zoelectric material. Provisions to prevent deviationfrom the specified trajectory. Canbe passive (e.g. flexure guidance)or active (e.g. using additional ac- tive axes). PZT: Translator: Acronym for plumbum (lead) zir-conate titanate. Polycrystalline ce- ramic material with piezoelectric properties. Often also used to refer to a piezo actuator or translator. Serial Kinematics: A linear actuator manufacturer. Unlike in parallel kinematics de-signs, each actuator acts upon a separate platform of its own. Thereis a clear relationship betweenactuators and axes. Advantages: Simpler to assemble;simpler control algorithm. Disadvantages: Poorer dynamiccharacteristics, integrated “Parallel Metrology” is not possible, cumu-lative guiding errors, lower accura- cy.
Flatness of a nanopositioning stage with active trajectory control is better than 1 nanometer over a 100 x 100 µm scanning range. Design principle of a stacked XY piezo stage(serial kinematics). © PI 1998-2005. Subject to change w/o notice. Cat 118 05/09.17 4-6