ABSTRACT
This chapter looks at the basics of lighting. It discusses some of the most familiar types of lamps and lighting, the eye and vision, and the eye’s response to different light levels. The oldest and the most widespread way of generating light is by bringing a solid body to incandescence by heating. An alternative and more efficient form of lighting is achieved by passing an electric current through a gas, exciting its atoms and molecules to emit radiation whose spectral distribution is characteristic of the gas present. The colour of the Light-Emitting Diode light is a function of the materials and the processes used in making the chip. Luminous intensity—symbol I, unit candela—is the concentration of luminous flux emitted in a specified direction. The distance from the eye to the surface, and the distance from the light source to the surface, are the critical factors.
