Patent ID: 8518030

Claim:
A method for controlling a pulsed laser, the method comprising: firing the laser to produce a series of laser pulses, each pulse fired by applying an associated voltage of the laser, wherein the laser comprises an excimer laser, and wherein the series of pulses are fired by applying at least four differing voltages to the laser while the laser is operating in a calibration mode and prior to transmitting pulses onto a target surface; measuring energies of each laser pulse of the series of laser pulses; generating a correlation between the measured energies of the pulses and the associated voltages of the laser, the correlation defining differing rates of change in pulse energy with changes in voltage; generating a first laser pulse by applying a first voltage to the laser; measuring a first energy of the first pulse; determining a second voltage for the laser so as to generate a second pulse with a desired pulse energy using the correlation and the measured first energy of the first pulse; and firing the laser by applying the second voltage so as to produce the second pulse; wherein the first and second laser pulses are directed onto the target surface while the laser is in an operating mode, wherein a firing rate of the laser varies while the laser is in the operating mode, and wherein the laser remains in the operating mode for less than about 10 minutes; and wherein the second voltage, Vnew, is calculated from the first voltage, Vold, using a damping factor D and a desired change in energy ΔE between the energy of the first pulse and the desired energy according to an equation: V new =V old +D (Δ E /(2 c 1 V old +c 2 )) In which generating a correlation comprises identifying constants c 1 and c 2 .