Development of an optical three-dimensional laser tracker using dual modulated laser diodes and a signal detector

Hau Wei Lee, Chieh Li Chen, Chien Hung Liu

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Laser trackers are widely used in industry for tasks such as the assembly of airplanes and automobiles, contour measurement, and robot calibration. However, laser trackers are expensive, and the corresponding solution procedure is very complex. The influence of measurement uncertainties is also significant. This study proposes a three-dimensional space position measurement system which consists of two tracking modules, a zero tracking angle return subsystem, and a target quadrant photodiode (QPD). The target QPD is placed on the object being tracked. The origin locking method is used to keep the rays on the origin of the target QPD. The position of the target QPD is determined using triangulation since the two laser rays are projected onto one QPD. Modulation and demodulation are utilized to separate the coupled positional values. The experiment results show that measurement errors in the X, Y, and Z directions are less than 0.05 when the measured object was moved by 300, 300, and 200 mm in the X, Y, and Z axes, respectively. The theoretical measurement error estimated from the measurement model is between 0.02 and 0.07 within the defined measurable range. The proposed system can be applied to the measurements of machine tools and robot arms.

Original languageEnglish
Article number035101
JournalReview of Scientific Instruments
Issue number3
Publication statusPublished - 2011 Mar 1

All Science Journal Classification (ASJC) codes

  • Instrumentation


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