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Optical Engineering

Multisource flash system for retroreflective beacon detection in CMOS cameras
Author(s): Håkan Fredriksson; Kalevi Hyyppä
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Paper Abstract

We present a method for improving a flash system for retroreflective beacon detection in CMOS cameras. Generally, flash systems are designed in such a manner that makes them suited for beacon detection in a small range interval. We strive to increase the flash system range interval by exploiting the directional properties of the retroreflector. Thus, light sources placed relatively far away from the optical axis of the camera will contribute only when the retroreflector is far away. This fact can be used to compensate for the 1/distance2 dependency of optical power. We present underlying theory and formulae, then describe a flash system consisting of several light-emitting diodes that was designed by considering the presented method. Simulations show that the usable flash range of the improved system can be almost doubled compared to a general flash system. Tests were performed indicating that the presented method works according to theory and simulations.

Paper Details

Date Published: 1 October 2008
PDF: 6 pages
Opt. Eng. 47(10) 103001 doi: 10.1117/1.3000582
Published in: Optical Engineering Volume 47, Issue 10
Show Author Affiliations
Håkan Fredriksson, Luleå Univ. of Technology (Sweden)
Kalevi Hyyppä, Luleå Univ. of Technology (Sweden)

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