Long period gratings as solution concentration sensors

The on-line concentration measurement of solutions is of great interest in many industrial processes as a means of quality production control, in orde r to measure concentrations of harmful solutions or solutions that cannot b e reached by the operator. An optical fiber long-period,orating (LPG), test ed for the refractometry of sodium chloride, calcium chloride and ethylene glycol aqueous solutions, is presented. Resolution values comparable to or even better than those offered by an Abbe refractometer, that is typically used in these types of measurements, an obtained (C) 2001 Elsevier Science B.V. All rights reserved.