Open AccessA fibre‐optic scalar irradiance microsensor: application for spectral light measurements in sediments
Author(s) -
Lassen Carsten,
Ploug Helle,
Jørgensen Bo Barker
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb04816.x
Subject(s) - irradiance , optics , materials science , spectral power distribution , radiation , radiant intensity , light intensity , optical fiber , photosynthetically active radiation , photosynthesis , physics , chemistry , biochemistry
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 μ m resolution.