METHOD AND DEVICE FOR MEASURING INDIRECTLY CONTENT OF ACCESSORY METAL IN SUBSTANCE ON SEABED BY UTILIZING PHOTOACOUSTIC PHENOMENON

摘要

PURPOSE:To enable the measurement of a content of a metal without taking directly a substance containing the metal out of the seabed, by making a photoacoustic sensor contact with said substance to which a periodically-intermittent light is applied, so as to detect a photoacoustic phenomenon thereof, and by determining the content of the metal from a photoacoustic spectrum obtained from said detection. CONSTITUTION:First, a substance located at the bottom of the water is searched by an underwater TV camera 12. Next, a photoacoustic sensor 11 is made to contact with said substance 15 and a periodically-intermittent light L of a light-emitting unit 4 is applied thereto in a light-extinguished state. A photoacoustic phenomenon thus occurring in the substance 15 is sensed by the photoacoustic sensor 11 provided with a piezoelectric element, and is detected as a piezoelectric phenomenon. A piezoelectric signal thus obtained is converted into an electric signal and this is transmitted to a measuring device 16 set in a ship on the surface. Then, the intensity of a photoacoustic spectrum calculated from the ratio between the intensity of a photoacoustic spectrum signal of the substance 15 obtained by the measurement by the device 15 and the intensity of a reference photoacoustic spectrum is compared with the characteristic curves of the intensity of a photoacoustic spectrum indicating the various contents of the known metal, and thereby the content of the known metal in the substance 15 is determined.