Far-field mapping of the longitudinal magnetic and electric optical fields.

In this Letter, we demonstrate the experimental mapping of the longitudinal magnetic and electric optical fields with a standard scanning microscope that involves a high-numerical-aperture far-field objective. The imaging concept relies upon the insertion of an azimuthal or a radial polarizer within the detection path of the microscope that acts as an optical electromagnetic filter aimed at transmitting selectively to the detector the signal from the magnetic or electric longitudinal fields present in the detection volume, respectively. The resulting system is thus versatile, noninvasive, and of high resolution, and shows high detection efficiencies. Magnetic optical properties of physical and biological micro- and nano-structures may thus be revealed with a far-field microscope.