Automatic optical fibre feedback potometer for transpiration studies
Irvine, J. J., Hadjiloucas, S., Keating, D. A. and Usher, M. J. (1996) Automatic optical fibre feedback potometer for transpiration studies. Measurement Science and Technology, 7 (11). pp. 1611-1618. ISSN 1361-6501
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To link to this item DOI: 10.1088/0957-0233/7/11/010
A new automatic feedback potometer for physiological studies of water uptake by root systems is described. A dual-optical-fibre amplitude-modulating displacement transducer of improved sensitivity is employed to detect the changes in liquid level. The merits of optimal double-cut fibres, which make full use of the critical angle and improve coupling between the emitter and the receiver, have resulted in a sensor that is 64 times more responsive than the simple emitter - detector probe. Positioning the optical fibre transducer in a narrow capillary and using feedback to control the liquid level allows continuous measurement of volumes in the nanolitre range. The optical sensor used does not need re-calibration for the different salt solutions used in such studies.