Technologie Glossar

The accuracy of a positioning systems is a result of static and dynamic positioning errors during the motion.

The accuracy of a motion system may depend on the point of interest of the application i.e., the distance from the end effector.

This parameter describes the angular error motion (pitch, yaw) during the full scan range of a Piezo-driven positioning stage.

The angular error motion of a positioning stage or motion system describes the parasitic pitch, yaw and roll rotation of the slide or end effector during a linear motion. They are determined over the whole travel range and are given as maximum value per travel distance (µrad/mm).

The aperture size is the diameter of the central aperture that is in the end effector or base plate of a single positioner or motion system.

The axial run-out describes the up-down movement of the surface of the rotation stage during the rotational motion.

The electrical connection cables of the positioners or motion systems are available in standardized lengths and can be made of certain materials (e.g., Teflon or Kapton sheathing), depending on the area of ​​application, e.g., in vacuum or cryogenic environments. Cable length is defined as the maximum distance from the cable exit of a positioner or system to the start of the connector.

Measure of the readiness of a system to be used in a cleanroom environment that affords a specific cleanliness according to ISO standards.

The connector for the electrical connections to the positioning or motion system can have the format of a D-SUB or round connector of type LEMO.

If the application requires the stage to lift a constant load mounted in a vertical arrangement, a constant force spring setup can be integrated to compensate the weight of the payload.

For applications that require very low temperatures down to the mK range, specialized versions of our SLC and SR stages are available. Please have a look at the cryogenic stages section of our environment-specific stages subpage.

External dimension of the motion system or single positioner at reference position.

The dynamic blocking force describes the maximum force in the direction of motion that can be generate during an open-loop motion. This strongly depends on the chosen step frequency.

The dynamic mass specifies the weight of the moving slide of a positioner or the top plate of a motion system.

Environmental specifications (i.e., temperature, humidity and pressure) that guarantee full functionality and lifetime of the motion system.

The (static) blocking force is the maximum external force a stick-slip stage can withstand without slipping. For certain applications, when the required blocking force is higher than specified in the product specifications tables, the stages can be modified to be increase the blocking force by 1.5 N without changing its outer dimensions.

The lift force describes maximum force that can be applied to the positioner to still allow a controlled closed-loop motion in vertical direction.

The linear error motion includes the flatness / straightness of a positioner or motion system. They describe the parasitic displacement from an ideal straight line in the axis perpendicular to the direction of motion. The flatness and straightness are evaluated over the full travel range and are defined as the maximum displacement in vertical (flatness) and horizontal (straightness) direction. In kinematic system, the flatness and straightness are measured in each degree-of-freedom, separately.

The specification of the materials refers to the material composition of the mechanical components, e.g., the base plate, the guides or system components. There are various options to choose from depending on the requirements, e.g., regarding the area of ​​application in vacuum or the non-magnetic properties.

Maximum sustainable acceleration of the motion with/without transport locks.

Maximum frequency of a Piezo drive in a stick-slip positioner under continuous operation.

The maximum normal load indicates the static load that can be mounted on the slide or top plate of a positioner or motion system. The movement system should be in horizontal alignment. The maximum load is reduced when the mounting is off-center or at different heights above the slide or top plate.

Maximum applicable voltage at a driving unit.

Minimum achievable total cumulative travel of the motion system under specified operating conditions.

The minimum incremental motion is the smallest repeatable closed-loop motion, i.e., the smallest closed-loop step, for which the standard-deviation of the measured step-size is smaller than 25% of its mean value. For example, when measuring a step-size of 1nm, the standard-deviation of these steps must be smaller than 0.25nm.

In the non-magnetic option, the motion system consists of components with low magnetic properties, such as ceramics, to be used in applications that are very sensitive to external magnetic fields. In most cases their outer dimensions remain unchanged. Please have a look at the non-magnetic piezo stages section of our environment-specific stages subpage.

The open-loop resolution is the smallest motion of a positioning stage or system, when performing an open-loop motion e.g. a scanning motion or step. This strongly depends on the type of motion controller that is used.

The piezo capacitance is the typical electrical capacitance of the Piezo drive in a stick-slip positioner or scanner.

Optical and inductive sensors can be integrated into our stages for closed-loop position control, allowing you to define the desired travel distance or the target position and the velocity of the stage.

The radial run-out describes the lateral movement of the rotating axis of a rotation stage during the rotation movement.

The referencing repeatability is a measure of reaching the reference position from single/multiply directions, when repeating a referencing procedure several times.

The repeatability is a measure of how precise a target position can be reached multiple times from one direction (uni-directional) or from multiple directions (bi-directional). The bi-directional repeatability is mostly dominated by the reversal error of the system.

The uni-directional repeatability is calculated from the standard deviation of the positioning error at each target position along the full travel of the motion system.

The reversal error is given as the difference in the measured mean positioning error when changing the approach direction toward a specific target position.

The repeatability of a motion system may depend on the point of interest of the application i.e., the distance from the end effector.

Required cleanliness of the application environment to ensure all specifications of the motion system.

The scan cut-off frequency specifies the drive frequency at which the amplitude of a scan movement drops to around 70% (-3dB) of the scan range. If, for example, positioners of the DLS type are operated with a drive frequency below this frequency, a scan movement is carried out over the full scan range. Frequencies above result in a scan amplitude of the order of a stick-slip step size.

The scan range is the maximum displacement that can be achieved by a Piezo-driven positioner, when only using the “scan mode”.

The sensor resolution describes the precision of measuring the current position in closed-loop mode. This is mainly limited by the position noise of the integrated optical sensor and the controller.

The static blocking force indicates the maximum holding force of a stick-slip positioner. This is also the external force needed to move the slide of a positioner over the entire travel range.

The step size of a positioner specifies the minimum guaranteed step length during an open-loop movement of a stick-slip positioner. It inherently depends on the primary properties of the drive used, e.g., the number of Piezos, but also on the type of motion parameters such as drive frequency or motion mode.

The stiffness or rotational stiffness is a measure of the displacement or rotation of the end effector/ slide of a positioner, when applying an external force in a specific direction.

The tilt error motion describes the tilting of the top plate of a rotation stage during the rotational motion.

The travel in each direction of motion of a single positioner or motion system is either limited by mechanical end-stops or in case of kinematic systems, by software limitations in the control environment.

Standard stages are configured to work in atmospheric pressure. For high vacuum (HV, 1E-6 mbar) and ultra-high vacuum (UHV, 1E-11 mbar) applications, specialized versions are available. As SmarAct is a complete solution provider, we deliver complete vacuum compatible single stages or multi-axis systems including vacuum compatible cabling and HV or UHV electrical feedthroughs. Please have a look at the ultra-high vacuum piezo stages section of our environment-specific stages subpage.

The velocity describes the mean change of position per time of a positioner or motion system.

The velocity stability corresponds to the velocity deviation (specified as a simple standard deviation) of the end effector (slide, top plate) during a closed-loop or open-loop movement.

Weight of a single positioner or motion system, without cables or connectors.