Oxford University Press (OUP), FEMS Microbiology Letters, 3(86), p. 247-254
DOI: 10.1016/0378-1097(92)90788-p
Oxford University Press, FEMS Microbiology Letters, 3(86), p. 247-254, 1992
DOI: 10.1111/j.1574-6968.1992.tb04816.x
Oxford University Press, FEMS Microbiology Ecology, 3(9), p. 247-254, 1991
DOI: 10.1111/j.1574-6941.1991.tb01759.x
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The manufacturing of a new spherical fibre-optic microsensor is described. The microsensor measures scalar irradiance, i.e. the spherically integrated light at a point in space. The light collector of the probe was a 70-μm diffusing sphere cast on the tip of a 125-μm wide optical fibre tapered down to 15–20 μm diametre. The microsensor had an isotropic (±10%) response from −160° to +160° over the whole spectral range from 400–900 nm in air as well as in water. The microsensor was coupled to a sensitive spectroradiometre and the spectral distribution of scalar irradiance in sediments was measured at 100 μm spatial resolution. Light was available for photosynthesis near the sediment surface at a higher intensity and a different spectral composition than could be expected from the illumination. By the combination of oxygen microelectrodes and the present fibre-optic microsensor it is now possible to study the depth distribution of microbenthic photosynthesis in relation to the available photosynthetically active radiation at ≤ 100 μm resolution.