INTERFERENCE IN FAR-FIELD RADIATION OF EVANESCENT FIELDS

We investigate experimentally the interference in far-field radiation of two contra-propagating evanescent fields using a conventional optical microscope. A laser beam illuminates a glass-air interface under total internal reflection condition and through the proper setup a double evanescent illumination was produced. The evanescent fields radiate from the surface into the far-field domain due to small surface scatterers. Thus, coherent interference is produced in the far-field region which is correlated with the relative positions of the evanescent illumination sources. Finally, the above-described could be considered as a device for high accuracy micro-scale measurements as well as a direct visualization method of evanescent phenomena.