Laser Trackers
Portable, large-volume metrology for assembly, alignment, tool building and machine calibration - measurement volumes of tens of metres, brought to the part.
How it works
A laser tracker measures the 3D position of a spherically mounted retroreflector (SMR) by tracking it with a laser interferometer or absolute distance meter (ADM), combined with two angular encoders. The tracker gives 3D coordinates in real time as the SMR is moved over the part, tooling or structure. Modern trackers add a 6-DOF probe (T-Probe, T-Scan) for hidden points and handheld scanning.
Typical accuracy
Leading trackers (Leica AT960/AT500, API Radian, FARO Vantage) achieve maximum permissible errors of roughly 15 microns + 6 microns/metre over volumes up to ~80 metres in diameter. Practical uncertainty on real assemblies is usually dominated by SMR nesting, environment and setup.
Applications
- Large aerospace assembly alignment (wings, fuselage, engine)
- Automotive body-shop tooling and fixture certification
- Machine tool volumetric error mapping and calibration
- Shipbuilding, energy and heavy fabrication alignment
- Foundation and bedplate levelling for large equipment
- As-built survey vs CAD for retrofit and installation
Strengths
- • Very large measuring volume - tens of metres in a single setup
- • Portable - brought to the part rather than the other way around
- • Real-time build guidance ('build to target')
- • 6-DOF probe reaches hidden features behind clamps and tooling
Limitations
- • Line-of-sight required from tracker to SMR
- • Accuracy degrades with distance - budget for multiple stations on large parts
- • Environmental factors (temperature gradients, air turbulence) matter
- • Not the right choice for small precision parts under 300mm
Interferometer vs Absolute Distance Meter
Traditional trackers used an interferometer (IFM) that had to stay locked on the beam - break the beam and you re-homed to a bird bath. Modern trackers combine IFM with an ADM so the operator can pick the SMR up, move to the next feature, and re-acquire without a bird-bath reset. This is the single biggest productivity gain in tracker measurement in the last 15 years.
6-DOF probes and scanning
The Leica T-Probe, API iProbe and FARO 6Probe use imaging cameras or LED constellations on top of the SMR to give full 6-DOF pose, enabling touch-probing of hidden features without moving the tracker. The Leica T-Scan / Absolute Scanner adds handheld laser-line scanning at tracker-grade accuracy.
Buying considerations
- Range and MPE at your working distances
- 6-DOF probe / T-Scan capability for hidden features and scanning
- Wireless and battery operation for shop-floor use
- Software: SpatialAnalyzer, Verisurf, PolyWorks, Metrolog
- Service, calibration and loan-tracker availability in the UK
FAQs
How many stations do we need on a 20-metre part?+
Usually two to four, tied together with common reference points. We plan station moves as part of the measurement uncertainty budget.
Can trackers be used indoors and outdoors?+
Yes - trackers are used routinely in hangars, ship halls and outdoors. Wind, temperature gradients and vibration all need managing in the uncertainty budget.