Noise is the standard deviation σ of all additionally captured random values made during any static or dynamic ongoing measurement at a specific bandwidth.


The stability is the change in bias over time.


Quotient of the change in an indication of a measuring system and the corresponding change in a value of a quantity being measured.

Alignment Tolerance

The angular alignment tolerance represents the target‘s tilt range in respect to the laser beam.

Alignment Tolerance IDS

Focal Length

The focal length F is the distance between the front side of the sensor head and the focal point.

Absolute Distance

Distance between the end of the fiber, which is represented by the mechanical stop, and the target.

Working Distance

Distance between the front side of the sensor head and the target where a continuous measurement is possible.

Environmental Compensation Unit (ECU)

The ECU detects variations in air pressure, temperature, and humidity to recalibrate the refraction index.

Fabry-Pérot Interferometer

A (Fabry-Pérot) interferometer consists of an optical cavity made from two parallel reflecting surfaces and creates interference of light by overlaying a reference and a measurement beam. By analysing the phase shift in the interference signal, the target displacement can be determined.


The precision is the standard deviation σ of a measurement. Its value is strongly related to the system’s noise level, its repeatability and – over duration – its stability.


Repeatability is the standard deviation (σ) of a set of a device's moving target approach measurements, all made under the same conditions. Approach measurements may be done from one or both sides of a target, specifying a devices uni- or bi-directional repeatability respectively.

Repeatability POS  IDS


Accuracy is the deviation of a device's measured displacement value compared to the true displacement of the target. Accuracy is defined as a percentage of the measured range.


The measurement resolution is the smallest increment of displacement that the sensor can show.

Ultra-High Vacuum (/UHV)

The ultra-high vacuum range is specified down to 5 ⋅ 10-11 mbar for most positioners. A few rotators and goniometers use UHV compatible grease. Due to the increased outgassing of these types at elevated temperatures, we specify them for 1 ⋅ 10-9 mbar as a precaution (noted in specification sheets). All UHV positioners can be baked out up to 150 °C.

High Vacuum (/HV)

The high vacuum range is specified down to 1 ⋅ 10-8 mbar.

Room Temperature (/RT)

/RT positioners are manufactured for use at ambient conditions (room temperature, dry atmosphere, ambient pressure).