scope:

This guideline applies to laser trackers. Laser trackers are measuring devices directing the light beam of a length-measuring system onto a retroreflective target and automatically tracking said target via a two-axes rotary control unit. The target position is defined by the measured distance and the angular position of the tracking unit and is recorded in a spherical coordinate system. Laser trackers can measure static targets and/ or can automatically lock on to moving targets, recording their positions continuously.

This guideline states procedures and test equipment for acceptance and periodic inspection of laser trackers. The procedures are equally suited for

• acceptance of laser trackers and

• the inspection of laser trackers (in the sense of inspection of test equipment as per DIN EN ISO 9000 through DIN EN ISO 9004).

The requirements to be met by the artefacts or the test equipment used for acceptance and inspection are specified, and some examples are described. Artefacts as defined in this guideline are linear, flat and spatial arrangements of features to be probed. Artefacts and test equipment shall be calibrated.

Characteristics allowing to assess the accuracy of laser trackers are specified. The limits not to be exceeded by these characteristics during acceptance of laser trackers are specified by the manufacturer; those applying to inspection are specified by the user.

The characteristics serve for laser tracker specification and for comparison of different measuring systems. These values being dependent upon the mode of operation and the operating conditions, it is recommended to state and specify specific modes of operation and operating conditions for acceptance and inspections in order to ensure comparability of the test results. The characteristics are not necessarily applicable to any measurement task.

Unless limitations to the modes of operation and operating conditions are agreed, the limits specified for the characteristics must be observed in any and all modes of operation and operating conditions. Where specified limitations are not complied with, exceeding the respective limits of the characteristics is possible and permissible.

Modes of operation are understood to be options for setting and configuring the laser tracker, for instance:

• type and shape of the retroreflector, of the handheld probe, if any, and the stylus configuration

• interferometric or absolute distance measurement measuring volume and location of the laser tracker with respect to the measuring volume

• operation of laser tracker either vertical, horizontal or at any angle

• 1- or 2-face measurement and evaluation

• time required for a static measurement

By operating conditions, the external factors influencing the laser tracker are understood. They include, e. g.:

• temperature and spatial and temporal temperature gradients

• air pressure and temporal air-pressure gradient

• humidity

• extraneous light

• vibrations (mechanical)

• electromagnetic interferences

• dust