After the LED light source is fully reflected and converged through the light guide element, the cut-off line of light and dark is imaged in the front position through LENS. A light guide — sometimes referred to as a light pipe — is a device that directs light from a light source (commonly an LED) to a place where the light is needed. These are collectoively called as Light Guide. The guide structure includes a light guiding bar having an upper surface and a lower surface and extending along a longitudinal direction.