Hau-Wei Lee and Chieh-Li Chen 2009 Meas. Sci. Technol. 20 125103 doi:10.1088/0957-0233/20/12/125103
Hau-Wei Lee and Chieh-Li Chen
Show affiliationsThis paper presents a two-dimensional tracking measurement system with a tracking module, which consists of two stepping motors, two laser diodes and a four separated active areas segmented position sensitive detector (PSD). The PSD was placed on a two-dimensional moving stage and used as a tracking target. The two laser diodes in the tracking module were directly rotated to keep the laser spots on the origin of the PSD. The two-dimensional position of the target PSD on the moving stage is determined from the distance between the two motors and the tracking angles of the two laser diodes, which are rotated by the two stepping motors, respectively. In order to separate the four positional values of the two laser spots on one PSD, the laser diodes were modulated by two distinct frequencies. Multiple-laser spot position measurement technology was used to separate the four positional values of the two laser spots on the PSD. The experimental results show that the steady-state voltage shift rate is about 0.2% and dynamic cross-talk rate is smaller than 2% when the two laser spots are projected on one PSD at the same time. The measurement errors of the x and y axial positions of the two-dimensional tracking system were less than 1% in the measuring range of 20 mm. The results demonstrate that multiple-laser spot position measurement technology can be employed in a two-dimensional tracking measurement system.
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
Accelerators, beams and electromagnetism
Instrumentation and measurement
Issue 12 (December 2009)
Received 30 May 2009, in final form 6 October 2009
Published 6 November 2009
Hau-Wei Lee and Chieh-Li Chen 2009 Meas. Sci. Technol. 20 125103
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