Introduction
The document introduces the concept of an ideal laser tracker that can instantly re-establish a broken laser beam and measure absolute distances with high precision and speed. Traditionally, laser trackers used separate technologies: laser interferometers (IFM) for relative distances and absolute distance meters (ADM) for absolute distances. The Absolute Interferometer (AIFM) combines these technologies to measure absolute distances to moving targets without accuracy loss.

History
Leica Geosystems pioneered the integration of ADM into laser trackers with the LTD500 in 1995, setting a new standard in the industry. Despite competitors focusing on speed over accuracy, Leica prioritized accuracy, leading to the development of 6DoF technology in 2004. The ADM technology, derived from the Kern Mekometer 5000, was known for its accuracy over long distances but was initially slow. The challenge was to enhance this technology to match the dynamic performance of IFM while maintaining accuracy.

Accuracy Improvement
The document details improvements in modulation frequency, frequency bandwidth, and synthesizer resolution to enhance accuracy. The AIFM increased the maximum modulation frequency to 2.4 GHz, achieving a typical accuracy of about 5 µm. By using a broadband light source, polarization errors were minimized, allowing consistent accuracy across the measurement volume.

Functionality Improvement
The AIFM combines ADM and IFM technologies to track relative movement during integration, allowing accurate measurements even if the reflector moves. This integration transforms the IFM into an absolute interferometer, providing sub-micron positional information.

Speed and Accuracy
The AIFM maintains accuracy during measurements, even with moving reflectors, unlike competitors' fast ADMs that suffer accuracy loss. The AIFM uses redundant sampling to ensure measurement reliability, preventing errors from affecting subsequent measurements.

Conclusion
The AIFM represents a significant advancement in laser tracker technology, combining mature IFM and ADM technologies to create a highly accurate and stable dynamic distancing unit. This innovation changes how laser trackers are used, offering a comprehensive solution to longstanding measurement challenges.

Additional Information
Hexagon Metrology, part of Hexagon, offers a wide range of metrology products and services across various industries, supporting customers throughout the product lifecycle. For more information, visit their website.