When properly calibrated and maintained, the FARO Laser Tracker ION, X, and Xi provides measurement data traceable to recognized international and national standards. Key components of the Laser Tracker system include the temperature sensor, atmospheric pressure sensor, the two angular encoders, the interferometer, and absolute distance meter (ADM).
For the ADM, the phase shift of the laser beam is a function of the frequency of a reference oscillator and the prevailing environmental conditions. For the optional interferometer, the wavelength of the laser light in the air is a function of a known wavelength in a vacuum and the prevailing environmental conditions. Because both the optional interferometer and the ADM depend on current environmental conditions, the accuracy of the temperature, pressure, and humidity sensors must be established.
The remote temperature sensor in the Tracker is calibrated at the factory by comparing readings to a NIST traceable precision standard temperature sensor. Traceability requires calibration based on the date listed on the certificate.
The pressure sensor in the Tracker is calibrated at the factory by comparing its readings to a NIST traceable precision standard pressure sensor. Traceability requires calibration based on the date listed on the certificate.
The humidity sensor in the FARO Laser Tracker is verified at the factory by comparing its readings with an independent relative humidity reading.
The helium neon (HeNe) laser source is calibrated to a NIST traceable HeNe source during the manufacturing process. This certification is valid for the life of the laser. NIST tracability for measurements taken with the IFM system are available through the optional ASME B89.4.19 System Calibration standard.
The ADM frequency oscillator is calibrated using the cesium clocks within the global GPS network. The ADM system is factory compensated and calibrated with a very accurate IFM system. These calibrations are one-time factory calibrations that are good for the life of the system. NIST tracability for measuerments with the ADM system is available through the optional ASME B89.4.19 System Calibration standard.
The angular encoders of the Tracker are mapped against a reference encoder during the manufacturing or service process. The encoders used are compared to NIST tracable standards. NIST tracability for measurements taken with the Tracker's complete angular system is available through the optional ASME B89.4.19 System Calibration standard.
Spherically Mounted Retroreflector
The accuracy of measurements made with the Tracker depend on these characteristics of the spherically mounted retroreflector (SMR).
- The ball diameter
- Vertex position
- Polarization characteristics
- Flatness of the optics
- Dihedral angle errors.
The specifications for the Tracker are valid when using SMRs certified by FARO. Mishandling of the SMR may change one or more of these characteristics and diminish the accuracy of the measurements taken with the Tracker.
traceability, ADM, Interferometer, temperature sensor, b89, trace, certification, traceable, NIST