Passive two-band plant fluorescence sensor with applications in precision agriculture

Paul L. Kebabian; Arnold F. Theisen; Spiros Kallelis; Herman E. Scott; Andrew Freedman

doi:10.1117/12.336885

14 January 1999 Passive two-band plant fluorescence sensor with applications in precision agriculture

Paul L. Kebabian, Arnold F. Theisen, Spiros Kallelis, Herman E. Scott, Andrew Freedman

Proceedings Volume 3543, Precision Agriculture and Biological Quality; (1999) https://doi.org/10.1117/12.336885
Event: Photonics East (ISAM, VVDC, IEMB), 1998, Boston, MA, United States

Abstract

We have designed and built a passive sensor of sunlight- excited chlorophyll fluorescence which provides for the real-time, in situ sensing of photosynthetic activity in plants. This sensor, which operates as a Fraunhofer line discriminator, detects light at the cores of the lines comprising the atmospheric oxygen A-band and B-bands, centered at 760 nm and 688 nm respectively. These bands also correspond to wavelengths in the far red and red chlorophyll fluorescence bands. The sensor operates on the principle that as light collected from the fluorescing plants is passed through a cell containing oxygen at low pressure, the oxygen will absorb the energy and subsequently re-emit photons which can be detected by a photomultiplier tube. Since the oxygen in the cell will absorb light at exactly the wavelengths that have been strongly absorbed by the oxygen in the atmosphere, the response to incident sunlight is minimal. This mode of measurement is limited to target plants that are close enough that the plants' fluorescence is not itself appreciably absorbed by atmospheric oxygen.

Citation Download Citation

Paul L. Kebabian, Arnold F. Theisen, Spiros Kallelis, Herman E. Scott, and Andrew Freedman "Passive two-band plant fluorescence sensor with applications in precision agriculture", Proc. SPIE 3543, Precision Agriculture and Biological Quality, (14 January 1999); https://doi.org/10.1117/12.336885

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