9 December 2004 Localizer with high occlusion immunity using diffraction optics
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The chromatic method of diffraction range finding can be exploited to construct localizers that track the 3-D positions of light sources. A spectrogram is made using a diffraction grating as the primary objective of an optical system that views broadband emitters such as a tungsten filaments or white phosphor L.E.D.’s. Computer image processing on spectra captured through the grating converts each spectrum at the input into a 3-D position at the output. The behavior conforms to the Diffraction Equation. This novel technique has unique advantages over prior art. Resolution is proportional to distance, because the number of samples increases with target distance. The plurality of samples overcomes occlusion liability, since multiple distinct paths exist between emitter and sensor. The grating can be made from inexpensive embossed plastic, and a wave length sensor can be constructed from a garden variety color 2-D array or ganged line scan IC’s. The method is robust at a grazing exodus angles that allow for a compact configuration of the receiver.In this paper we disclose the theory of operation including a mathematical model, and we demonstrate the method empirically using a simple example of tracking a light as a 3-D input method for a workstation.
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Thomas D. Ditto, Thomas D. Ditto, Jacques Farges, Jacques Farges, } "Localizer with high occlusion immunity using diffraction optics", Proc. SPIE 5578, Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education, (9 December 2004); doi: 10.1117/12.567583; https://doi.org/10.1117/12.567583

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