Patent ID: 8681832

Claim:
A dual chamber gas discharge laser light source, comprising: a master oscillator having a laser chamber containing a lasing medium as comprising a halogen; an amplifier having a laser chamber containing a lasing medium gas comprising the halogen; a gas replenishment system including a controller configured to perform a replenishment scheme for a selected laser chamber of either the master oscillator or the amplifier at inject opportunities occurring at regular intervals, the replenishment scheme comprising: for a first number of inject opportunities, injecting into the selected laser chamber at each inject opportunity a fixed quantity of a non-halogen containing gas and a fixed quantity of a halogen containing gas; after the first number of inject opportunities, for each of a second number of inject opportunities: running a model of the amount of halogen gas in the selected laser chamber before each inject opportunity and the amount of halogen gas to be injected to the selected laser chamber during the inject opportunity to predict the amount of the halogen as in the selected laser chamber after the inject opportunity; injecting into the selected laser chamber a fixed quantity of the non-halogen containing gas and a fixed quantity of the halogen containing gas; measuring a parameter of the laser light source to estimate the amount of halogen gas in the selected laser chamber after the injection of gas; updating the model based upon the difference between the predicted amount of halogen gas in the selected laser chamber and the estimated amount of halogen gas in the selected laser chamber; and after the second number of inject opportunities, for each of a third number of inject opportunities; running the model to predict a quantity of halogen containing gas to be injected that will result in a desired amount of halogen as in the selected laser chamber; and injecting into the selected laser chamber at each inject opportunity a fixed quantity of the non-halogen containing gas and the predicted quantity of the halogen containing gas predicted to result in the desired amount of halogen as in the selected laser chamber after the inject opportunity.