Laser Pointer

A laser pointer (or laser pen) is a small portable device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light. The small width of the beam and low power of typical laser pointers make the beam invisible in a reasonably clean atmosphere, only showing a point of light when striking an opaque surface.