In optics, an optical surface which has been made substantially flat, the degree of flatness depending upon the performance required. A plano-convex lens is a positive lens with one surface flat and the other convex. See optical flat . The phenomenon of a substance showing different absorption colors in different vibration directions of polarized light. The observed colors change with the orientation of the crystal and can be seen only with plane polarized light, i.e., a single polar.
Resolution depends primarily on the diameter of the source.
The mathematical representation of the image of a point source. See also three-dimensional diffraction pattern . Related points in the object and image are located optically so that one is the image of the other. See Michel-Levy scale of retardation colors . However, naturally polarized light is, on the whole, rather imperfectly polarized.