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Range imager performance comparison in homodyne and heterodyne operating modes

Abstract
Range imaging cameras measure depth simultaneously for every pixel in a given field of view. In most implementations the basic operating principles are the same. A scene is illuminated with an intensity modulated light source and the reflected signal is sampled using a gain-modulated imager. Previously we presented a unique heterodyne range imaging system that employed a bulky and power hungry image intensifier as the high speed gain-modulation mechanism. In this paper we present a new range imager using an internally modulated image sensor that is designed to operate in heterodyne mode, but can also operate in homodyne mode. We discuss homodyne and heterodyne range imaging, and the merits of the various types of hardware used to implement these systems. Following this we describe in detail the hardware and firmware components of our new ranger. We experimentally compare the two operating modes and demonstrate that heterodyne operation is less sensitive to some of the limitations suffered in homodyne mode, resulting in better linearity and ranging precision characteristics. We conclude by showing various qualitative examples that demonstrate the system’s three-dimensional measurement performance.
Type
Conference Contribution
Type of thesis
Series
Citation
Richard M. Conroy, Adrian A. Dorrington, Rainer Künnemeyer, and Michael J. Cree, "Range imager performance comparison in homodyne and heterodyne operating modes," Three-Dimensional Imaging Metrology, J. Angelo Beraldin, Geraldine S. Cheok, Michael McCarthy, Ulrich Neuschaefer-Rube, Editors, Proc. SPIE, 7239, 723905 (2009).
Date
2009
Publisher
SPIE and IS&T
Degree
Supervisors
Rights
Copyright 2009 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.