A new technique for IR spectroscopic measurements of liquids, pastes and thin films is reported. The technique is based on the evanescent field absorption occurring when the material forming the cladding of a waveguide absorbs light at the wavelength being transmitted. The spectroscopic system, consisting of an IR tunable diode laser source and an unclad multimode IR fibre, is described. Design considerations, theoretical predictions and experimental verification of the sensor performance are presented. This sensor has a relatively high sensitivity, and it will be very useful for monitoring and controlling concentrations and chemical transformations of liquids and pastes in situ and in real time.
|Number of pages||5|
|Journal||Materials Science and Engineering B: Solid-State Materials for Advanced Technology|
|State||Published - Jan 1990|