The LASER BEACON is part of the time calibration system of the ANTARES telescope and has been developed completely at IFIC. It emits high intensity light pulses ( > 1 microJ) of very short duration (< 1 ns) and is located at the bottom of the central lines. This device is controlled by a motherboard that can be programmed directly from shore. The main component is a diode pumped Q-switched Nd-YAG laser, model NG-10120-120 from Nanolase, emitting at 532nm (green). The laser is contained inside a titanium cylinder able to support the pressure of the seabed.