High-precision synchronization of pulsed gas-discharge lasers
AssigneeCoherent, Inc.
InventorsAndreas Targsdorf, Rainer Desor
Life of this patent
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Abstract
Two excimer lasers have individual pulsing circuits each including a storage capacitor which is charged and then discharged through a pulse transformer to generate an electrical pulse, which is delivered to the laser to generate a light pulse. The time between generation of the electrical pulse and creation of the light pulse is dependent on the charged voltage of the capacitor. The capacitors are charged while disconnected from each other. The generation of the electrical pulses is synchronized by connecting the capacitors together for a brief period after the capacitors are charged to equalize the charging voltages. The capacitors are disconnected from each other before they are discharged.
Claims19
A laser system comprising:
- a first laser tube holding a gas and discharge electrodes;
- a second laser tube holding a gas and discharge electrodes;
- a first circuit including a first storage capacitor and first power supply for charging the first capacitor and wherein the first circuit delivers excitation pulses to the discharge electrodes in the first laser tube in response to the discharge of the first capacitor;
- a second circuit including a second storage capacitor and second power supply for charging the second capacitor and wherein the second circuit delivers excitation pulses to the discharge electrodes in the second laser tube in response to the discharge of the second capacitor;
- and
- at least one switch arranged to electrically couple the first and second storage capacitors together prior to the discharge thereof to reduce any differences in the charging voltages of the first and second capacitors.
A laser system comprising:
- a first laser tube holding a gas and discharge electrodes;
- a second laser tube holding a gas and discharge electrodes;
- a first circuit including a first storage capacitor and first power supply for charging the first capacitor and wherein the first circuit delivers excitation pulses to the discharge electrodes in the first laser tube in response to the discharge of the first capacitor;
- a second circuit including a second storage capacitor and second power supply for charging the second capacitor and wherein the second circuit delivers excitation pulses to the discharge electrodes in the second laser tube in response to the discharge of the second capacitor;
- and
- means for electrically coupling the first and second storage capacitors together after being charged and before being discharged to reduce any differences in the charging voltages of the first and second capacitors.
A method of laser annealing wherein the laser output pulses of two excimer laser are spatially and temporally overlapped, each said excimer laser having an electrical pulse supply circuit, each said pulse supply circuit including a capacitor comprising the steps of:
- charging the capacitors;
- electrically coupling the capacitors together to reduce any difference in the charges on the capacitors;
- discharging the capacitors to supply pulses to the respective excimer lasers to generate laser output pulses;
- and
- spatially and temporally overlapping the pulses from the respective excimer lasers to facilitate annealing.
A method of controlling the output from two gas lasers, each gas laser having an electrical pulse supply circuit, each said pulse supply circuit including a capacitor comprising the steps of:
- independently charging the capacitors from two separate power supplies;
- after the capacitors are charged, electrically coupling the capacitors together to reduce any difference in the charges on the capacitors;
- thereafter, uncoupling the capacitors;
- and
- thereafter discharging the capacitors to supply pulses to the respective gas lasers to generate laser output pulses.
Dependencies are inferred from the claim text.