Light from a character or point of the phosphor is not diffused when it passes through the front surface. As Figure 44 indicates, light rays are reflected from a surface at the same angle that they strike it. Reflections of rays from the brightest sources are, therefore, unlikely to be a problem because those sources are usually overhead and the rays are reflected downward. Reflections of rays from dimmer sources may reach the eye, but, because of their dimness, are not much of a problem. This method, typically used on commercial lenses, involves treating the glass surface of the display screen.
Light travels at different speeds through different media.
The index of refraction of a particular piece of glass is the speed of light through a vacuum divided by the speed of light through that glass. This process is apparent on older camera lenses, which have a magenta-colored appearance. That type of lens typically had a single layer of thin-film coating matched for the center of the visual spectrum. Reflections in the green-yellow range are minimized, but reflections from the ends of the spectrum, red and blue, are about the same as for untreated glass. In that case, the red and blue reflections are seen as magenta.