Abstract: There is described a fiber-optic sensor for measuring a light signal from a fluorescible sample comprising heavy metal ions, for example. The fiber-optic sensor comprises an optical fiber having a side surface by which the light signal from the fluorescible sample is inputted. The optical fiber is corrugated to form at least two gratings on the side surface of the optical fiber. Each grating comprises periodically longitudinally spaced-apart valleys on the surface of the optical fiber, and is longitudinally spaced apart from any other grating of the at least two gratings.

Abstract: There is described a fiber-optic sensor for measuring a light signal from a fluorescible sample comprising heavy metal ions, for example. The fiber-optic sensor comprises an optical fiber having a side surface by which the light signal from the fluorescible sample is inputted. The optical fiber is corrugated to form at least two gratings on the side surface of the optical fiber. Each grating comprises periodically longitudinally spaced-apart valleys on the surface of the optical fiber, and is longitudinally spaced apart from any other grating of the at least two gratings.

Abstract: There is disclosed a method and a system for laying out optical fibres across an aperture in a wall separating a high pressure zone from a low pressure zone. It involves a plug member sealingly mounted across the aperture and formed with an axial through fibre passage having a conical first portion and a second portion of constant cross-section. A conical wedge member is freely inserted into the first passage portion and is formed with a series of grooves on its outer surface leading into the second passage portion. A plurality of optical fibres are divided into fractions and each fraction is received into one of the grooves; all fibres being thereafter collected into the second passage portion. Plastics material is introduced in the grooves and in the second passage portion to completely embed the fibres while adhering to the walls of the grooves and of the second passage portion.