Providing of gases for an excimer laser

DETAILED DESCRIPTION In FIG.
1 the closed-cycle excimer laser system centers around the excimer laser 10.
The excimer laser 10 is a conventional design and in its lasing chamber has a gas mixture of a halogen, a heavy rare gas and a diluent rare gas.
A typical lasing gas mixture would be a halogen gas such as flourine or gaseous hydrogen chloride in concentrations of 10ths of a percent, a heavy rare gas such as argon, krypton or xenon in concentrations of the order of 2 to 5 percent and a diluent range gas such as helium and/or neon in concentrations in the order of 95 percent.
Because of the lasing action, there are formed gaseous and particulate compounds which if not removed from the laser will eventually reduce the efficiency of operation and finally quench any possible lasing action.
Therefore, in accordance with the invention, the lasing mixture is exhausted or removed from the excimer laser 10 and passed through the cleanup means 12.
In the cleanup means 12 the halogen compounds are removed from the gas mixture so that at the output of the cleanup means 12 there is a pure gas mixture of the heavy rare gas and the diluent rare gas.
The cleaned gas mixture is fed via a check valve 16 back to the excimer laser 10.
Since the halogen has been removed it is now necessary to replenish the gas mixture with the halogen gas.
Accordingly, there is also fed into the input of the laser 10 a supplement gas mixture from the source 18.
This gas mixture includes the halogen, the heavy rare gas and the diluent rare gas in percentages related to the original gas mixture.
In particular, the halogen in the supplemental gas mixture is substantially greater in concentration than the original concentration.
In particular, its percentage is at least one order of magnitude greater and typically 50 times greater.
Thus, it is not unusual for the supplemental gas mixture to be in the order of 10 percent halogen.
The remainder of the supplemental gas mixture is a combination of the heavy rare gas and the diluent rare gas