Evanescent optical waveguide microscopy is a novel imaging technique both in life and material sciences. Some years ago our group had demonstrated “Evanescent Scattering Microscopy” as a novel tool for the enhancement of contrast in a patterned ultra thin film sample. Here the evanescent field was scattered by material deposited right on the waveguide and the light scattered out was collected perpendicular to the waveguide for imaging. The contrast here was depending both on the mode number, basically the penetration depth of the evanescent field into the sample, and the polarization used. We like to extend these successful scattering experiments towards fluorescence microscopy, where fluorescence dyes are only excited within the evanescent field of a waveguide, namely with a few hundreds of nm above the waveguide surface. This will allowinvestigating surface and interface issues in biology and material sciences. As a simple example the delaminating of an ultra thin film from the waveguide deposited with and without the help of a primer or an adhesive agent can be investigated in detail. Drug studies on cell death and cell death studies itself e.g. on cancer cells which detach when they die, can be easily studied monitoring the integral fluoresce signal over time. For the development of such a new evanescent fluorescence microscope we are fabricating waveguides with a specific numbers of modes in TE and TM polarization in BGG-11 glass, a new development of Schott, Mainz. We have established a routine by ion exchange to achieve waveguides with defined numbers of modes. The diffusion profile of the exchanged Ag ions can be calculated. The next step is to design a measurement cell and to determine the decay length of the evanescent field into the sample space for the various waveguide modes.
