Method and system for detecting a body in a zone located proximate an interface

A system for detecting an object in a zone situated in the proximity of an interface between two liquid media and/or gaseous media;

• the said object being illuminated by electromagnetic radiation comprising at least two different wavelengths;
• the said media having different absorption coefficients as a function of the wavelengths of the electromagnetic radiation;
• the said system comprising:
• selecting means for choosing, from among the wavelengths of the electromagnetic radiation, at least two wavelengths or two wavelength regions,
• filming means for creating, for each of the said wavelengths or wavelength regions, an image of the said interface and of the said zone,
• converting means for producing electrical signals representative of each image,
• digitizing means for digitizing the electrical signals in such a way as to produce data corresponding to each image,
• information-processing means for extracting, from the said data corresponding to each image, two groups of data, wherein the groups are representative of at least part of the said object in the near infrared region and in the blue-green region respectively, and
• calculating means for comparing the said groups of data;
• the converting means, the digitizing means, the information-processing means and the calculating means being referred to hereinafter as the means for deducing the presence of an object,
• whereby detecting the presence of an object and/or determining the position of the detected object relative to the said interface, while discriminating between an object situated under the interface and an object situated at least partly above the interface.