Patent ID: 7822084
Filing Date: 2010-10-26
Classification: G03F,H01S

Abstract:
1. A method of controlling bandwidth in a laser system comprising: a gas discharge seed laser having a cavity and producing a seed laser output; a gas discharge amplifier laser amplifying the seed laser output and producing a laser system output; a bandwidth metrology unit which measures the bandwidth of the laser system output and provides a bandwidth measurement; and a bandwidth error signal generator which receives the bandwidth measurement and a bandwidth set point and provides a bandwidth error signal; a variable magnification line narrowing unit within the cavity of the seed laser comprising a grating and a variable beam magnification optical system; a differential timing controller selecting the timing of the firing of a discharge between a respective pair of electrodes in the seed laser and a respective pair of electrodes in the amplifier laser; the method comprising: controlling bandwidth with a bandwidth controller having at least two modes of magnification control including an independent mode that adjusts the magnification of the beam in the line narrowing unit to a selected value independent of the bandwidth error signal and a feedback mode that adjusts the magnification of the beam in the line narrowing unit in response to the bandwidth error signal, and wherein in each mode the differential timing controller selects the timing in response to the bandwidth error signal or without regard to the bandwidth error signal.