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Optical Engineering

High-resolution rangefinder with a pulsed laser developed by an undersampling method
Author(s): Masahiro Ohishi; Fumio Ohtomo; Masaaki Yabe; Mitsuru Kanokogi; Takaaki Saito; Yasuaki Suzuki; Chikao Nagasawa
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Paper Abstract

A high-resolution rangefinder equipped with a pulsed laser has been developed by introducing a high-resolution interpolation technique based on an undersampling method. Using this pulse method employed by the rangefinder, a new time-scale expansion has been realized that is similar to the heterodyne of the rangefinder that also employs the phase difference method. Therefore, high-resolution measurements are now possible. A bandpass-filtered temperature-compensated crystal oscillator signal with a reference frequency of 15 MHz is sampled at a timing determined by a received pulsed light with a repetition rate of 8.5 kHz. With this process, a time series of undersampled 2.5-kHz data are obtained as an intermediate step that can be further lowered to 85 Hz by final rearrangement of the undersampled data. With this technique, a reference frequency is transformed into a lower frequency. A distance is then calculated from the phase of this low frequency. The rangefinder developed shows good performances that include a range resolution of better than 1 mm, nonlinearity within ±1 mm, and a measurement range of up to 7000 m.

Paper Details

Date Published: 1 June 2010
PDF: 8 pages
Opt. Eng. 49(6) 064302 doi: 10.1117/1.3456624
Published in: Optical Engineering Volume 49, Issue 6
Show Author Affiliations
Masahiro Ohishi, Topcon Corp. (Japan)
Fumio Ohtomo, Topcon Corp. (Japan)
Masaaki Yabe, Topcon Corp. (Japan)
Mitsuru Kanokogi, Topcon Corp. (Japan)
Takaaki Saito, Topcon Corp. (Japan)
Yasuaki Suzuki, Topcon Corp. (Japan)
Chikao Nagasawa, Tokyo Metropolitan Univ. (Japan)

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