Atmospheric pulsed gas laser apparatus

In a pulsed gas laser apparatus for operation at ambient pressure, said apparatus including a laser module, means for supplying laser gas to said laser module, said module having a tubular window open at its distal end for coupling and uncoupling of a laser beam, the improvement comprising;

• a) said tubular window having a volume which is at least equal to, or a multiple of, a volume change of the laser gas in the module during pulsed laser operation;
• b) the tubular window extends from the laser module in an essentially vertical orientation and includes a mixing zone in which during said pulsed operation laser gas and ambient gas are both present, said tubular window extending from the laser module downwardly when the laser gas is lighter than the ambient gas and upwardly when the laser gas is heavier than the ambient gas;
• and
• c) means for controlling the laser gas volume supplied to said module which is discharged through said tubular window such that a concentration of the ambient air entering said mixing zone through the open distal end of said window remains below a predetermined limit.