Near-infrared sensing utilizing the evanescent field

✍ Scribed by A.R. Lennie; F. Kvasnik

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 549 KB
• Volume: 281
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(93)85181-i

✦ Synopsis

A new fibre optic sensing system used to determine the water content of a soivent is described. The transduction mechanism is absorption of the evanescent field by the water with the consequent reduction of the transmitted optical power in an optical fibre. The viability of this sensing system was demonstrated on mixtures of water and acetone using 950-nm excitation which overlaps the O-H stretching overtone of water. A complex non-linear relationship between transmitted optical power, absorbant concentration and the length of the interaction region was observed and is discussed in detail.