Laser trackers and the software that control them have revolutionized the way metrology data has been taken over the last 20 years. With software and hardware advances, taking measurements has become more efficient and accurate.

One of these advances in metrology software is the ability to measure the angle normal to a mirrored surface with a laser tracker by first measuring a stationary spherically mounted retroreflector (SMR) through the mirror, and then measuring the same SMR directly. This technique has become a replacement for the traditional method of measuring the angle normal to a mirrored surface with auto-collimating theodolites. With this improved measurement technique comes a question: What is the accuracy? There are two variables to this measurement technique that will be studied in this article to answer that question. The first is the distance between the laser tracker and the mirrored surface. The second is the angle of incidence of the laser beam to the mirrored surface.

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