Transmission of Optical Energy Along Surfaces: Part I, Homogeneous Media

Abstract

When well-collimated light beams are incident near the critical angle upon a portion σ1 of a plane interface between two dielectric media, light flux can flow along the interface to a neighboring portion σ2 and reappear within the denser medium at the critical angle. Qualitative experiments together with a few precise experiments are presented for ascertaining the nature of this power flow along interfaces between homogeneous media. The observations are shown to be consistent with the interpretation that the beam suffers refraction into the less dense medium and that diffraction at area σ1 deviates considerable power along the grazing direction into the area σ2. Precision goniometry shows that this power redirected along the grazing direction possesses a sharp maximum for monochromatic beams at an angle of incidence about one second of arc below the critical angle for total internal reflection.