Patent ID: 6493370
Filing Date: 2002-12-10
Classification: G03F,H01S

Abstract:
A gas discharge laser system, comprising:a laser tube including a discharge chamber portion and a gas flow vessel portion, the laser tube containing a laser gas mixture including a halogen-containing constituent gas which is subject to depletion; a blower and a heat exchanger within the gas flow vessel portion of the laser tube; a plurality of electrodes within the discharge chamber connected to a power supply circuit for providing a driving voltage to said electrodes in a range between substantially 10 kV and 20 kV as a pulsed discharge to energize said laser gas mixture; a resonator including said discharge chamber and a pair of resonator reflectors for generating a pulsed laser beam; a gas supply unit connected to said discharge chamber, the gas supply unit including gas supply lines, valves and a pressure-controlled compartment of known volume which receives gas from the gas supply lines and from which gas is injected into the laser tube; and a processor for controlling gaseous flow between said gas supply unit and said discharge chamber by signaling the gas supply unit to perform gas injections into the laser tube, the processor operating according to an algorithm for periodically determining gas actions for the gas supply unit to smoothly perform the gas actions which stabilize a composition of the laser gas mixture within the discharge chamber and to stabilize significant parameters of the laser beam, wherein said gas supply unit and said processor are configured to permit a quantity in a range substantially between 0.0001 mbar and 0.2 mbar of said halogen-containing constituent gas to inject into said laser tube at selected intervals, such that a degradation of the halogen-containing constituent gas is automatically compensated without substantially disturbing laser beam parameters, thereby permitting the system to maintain stable laser beam parameters during operation.