An automatic F2 laser gas control, for a modular high repetition rate ultraviolet gas discharge laser. The laser gas control includes techniques, monitors, and processor for monitoring the F2 consumption rates through the operating life of the laser system. These consumption rates are used by a processor programmed with an algorithm to determine F2 injections needed to maintain laser beam quality within a delivery range. Preferred embodiments include F2 controls for a two-chamber MOPA laser system.