Headlight for vehicle

A headlight for a vehicle adapted to be operated by a direct-current power source, comprising:

• a high-pressure metal-vapor discharge lamp including a luminescent tube having at least sodium sealed therein as a luminescent metal, and including positive and negative electrodes having their respective distal ends spaced at a predetermined distance from each other and located in the luminescent tube;
• and
• a reflector having a focus and reflecting a light beam, emitted from the discharge lamp, in a forward direction from the front of the vehicle,
• said discharge lamp being positioned along a straight line connecting the respective distal ends of the positive and negative electrodes, said straight line being horizontal and passing through the focus, and said discharge lamp being arranged to fulfill the following requirement so that the luminescent region of reddish light radiated from said at least sodium is located at the same position as the focus:
• 0.ltoreq.L0/L1.ltoreq.0.4,
• where L0 is the distance between the focus and the distal end of the negative electrode, and L1 is the predetermined distance between the respective distal ends of the positive and negative electrodes;
• said discharge lamp in cooperation with said reflector producing a light beam having a luminous distribution pattern with reddish light, radiation from said at least sodium, being located at a center thereof and light of other colors being located around the reddish light.