The experiment is embedded in a study called Analysis and modelling of diffusion/dispersion-limited reactions in porous media (Short title: Reactions in Porous Media).
A grating coupler system has been designed with both high spatial and refractive index resolution capability. Fields of application are
- phase boundaries between water and non-aqueous pollution liquids (NAPL);
- interfaces between water and tar oil;
- biodegradation of toluene and similar organic pollutants in water.
In the case of biodegradation studies the system sensitivity for water contaminants has been increased by coating the sensor surface with pre-concentrating media.
In order to simultaneously cover the height and angle range a He-Ne laser beam (632.8 nm) is expanded and line-focussed onto the grating by a cylindrical lens. Only the resonant angles interact with the grating-coupled waveguide and contribute to the sensor output signal. The CCD camera registers the angle of the out-coupled beam as a function of height in a single frame.
