Multispectral time-of-flight imaging using light-emitting diodes

Griffiths, Alexander D. and Chen, Haochang and Li, David Day-Uei and Henderson, Robert K. and Herrnsdorf, Johannes and Dawson, Martin D. and Strain, Michael J. (2019) Multispectral time-of-flight imaging using light-emitting diodes. Optics Express, 27 (24). pp. 35485-35498. ISSN 1094-4087 (

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Multispectral and 3-D imaging are useful for a wide variety of applications, adding valuable spectral and depth information for image analysis. Single-photon avalanche diode (SPAD) based imaging systems provide photon time-of-arrival information, and can be used for imaging with time-correlated single photon counting techniques. Here we demonstrate an LED based synchronised illumination system, where temporally structured light can be used to relate time-of-arrival to specific wavelengths, thus recovering reflectance information. Cross-correlation of the received multi-peak histogram with a reference measurement yields a time delay, allowing depth information to be determined with cm-scale resolution despite the long sequence of relatively wide (~10 ns) pulses. Using commercial LEDs and a SPAD imaging array, multispectral 3-D imaging is demonstrated across 9 visible wavelength bands.