System and method for extending gas life in a two chamber gas discharge laser system

摘要

A method and system for performing injects of halogen gas into the chambers of a two chamber gas discharge laser such as a MOPA excimer laser for allowing operation of the laser within acceptable parameters and compensating for ageing effects without the necessity of performing refills is described. A parameter reflecting efficiency of the laser is measured, and the change in the parameter with respect to the length of laser operation is estimated. The change in the parameter with respect to the pressure in one of the chambers is also measured. At a given time, the total change in the value of the parameter is estimated, and from this change in pressure that is needed to reverse the change in the value of the parameter is calculated. The pressure in the chamber is then changed to correct for the amount of time that the laser has been in operation.

主权项

1. A dual chamber gas discharge laser light source, comprising:
a master oscillator having a laser chamber containing a lasing medium gas comprising a halogen; an amplifier having a laser chamber containing a lasing medium gas comprising a halogen; and a gas replenishment system including a controller configured to perform a replenishment scheme in a selected laser chamber at inject opportunities occurring at regular intervals, the replenishment scheme comprising:
injecting into the selected laser chamber at each inject opportunity a quantity of a non-halogen containing gas and a quantity of the halogen containing gas estimated to result in a desired amount of halogen gas in the selected laser chamber after the inject opportunity; andafter each M injects, where M is a predetermined number greater than 1, increasing a total operating pressure in the selected laser chamber for a next number of multiple injects to compensate for any change in the efficiency of the laser due to the length of operation of the laser.