Abstract
A novel device using optical fiber has been developed in order to measure the spectroscopic characteristics of sea water. The mechanism of this device is as follows.
1) The light passed through sea water is guided to the optical device by the optical fiber and the irradiance both just under the water surface and at certain depth of the sea is measured.
2) Absorbance (attenuance) is estimated from the irradiance determined at different depth of the sea. The spectra obtained by the present apparatus agree well with those by the conventional spectrophotometer. The result at cloudy weather is reliable, however, under clear sky with the seawater being transparent, the noise becomes remarkable. The noise originates from the fluctuation of the angle between the edge face of the optical fiber and the direction of the light in the sea ; this noise can be eliminated by covering the edge face with a ball of table tennis, by which the directivity of the light is relaxed.
