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Proceedings Paper

Optimum injection current waveform for a laser rangefinder based on the self-mixing effect
Author(s): Karl Bertling; John R. Tucker; Aleksandar D. Rakic
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Paper Abstract

In a self-mixing type laser range finder the current of the laser is modulated with a triangle wave to produce a range of optical frequencies. However, the electrical signal does not produce a perfect linear sweep in optical frequency due to thermal and other effects in the laser. This leads to errors in the accuracy and resolution of the range finder. In this paper, we describe and implement a method in software to systematically determine the optimal shape of the injected waveform needed to eliminate these thermally induced measurement errors. With this method we do not require the more complicated and expensive optical techniques used by other researchers to recover the optical frequency variations with regard to injection current. The averaging of a reasonable number of samples gave sub-millimeter accuracy when the optimal current shape was used. The uncertainty in the average measurements are improved by roughly six times compared to the conventional triangular modulation. The reshaping also results in the range finding system being less sensitive to changes in ambient temperature.

Paper Details

Date Published: 25 March 2004
PDF: 12 pages
Proc. SPIE 5277, Photonics: Design, Technology, and Packaging, (25 March 2004); doi: 10.1117/12.523267
Show Author Affiliations
Karl Bertling, Univ. of Queensland (Australia)
John R. Tucker, Univ. of Queensland (Australia)
Aleksandar D. Rakic, Univ. of Queensland (Australia)

Published in SPIE Proceedings Vol. 5277:
Photonics: Design, Technology, and Packaging
Chennupati Jagadish; Kent D. Choquette; Benjamin J. Eggleton; Brett D. Nener; Keith A. Nugent, Editor(s)

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