| However, a certain tiny amount of dripping light does, in fact, penetrate from the tip of an optical fiber. This is near-field light. This phenomenon occurs because the point of incidence, where the incident beam strikes a surface, and the point of reflection are not absolutely the same, even in total reflections, or cases in which the entire incident light is reflected at the surface. These points are deemed to be the same at the level of high school physics, and in general there's no problem with doing so, but the fact is that they are separated by a distance of one wavelength. In cases of total reflection, a tiny portion of the incoming light spills over, and as shown in the diagram below, makes a detour of one wavelength before arriving at the point of reflection, where reflected light emerges as if reflected from a single point. The light that spills over is near-field light. Light possesses this property to spill over, and the dripping light appearing at the tips of optical fibers is near-field light that has spilled over.
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