Patent ID: 7046705

Claim:
A laser oscillator comprising: a discharge tube for exciting laser gas; at least a pair of mirrors disposed along an optical axis of laser light emitted by the laser gas excited in said discharge tube; at least a pair of mirror retainers for retaining said oair of mirrors individually; a laser gas passage in connection with said discharge tube; laser gas circulation means for circulating the laser gas in said laser gas passage and said discharge tube; and heat control means for controlling heat generated in at least one of said mirrors and said laser gas circulation means, wherein said heat control means comprises: a first coolant passage provided for cooling said laser gas circulation means; a second coolant passage provided for cooling said pair of mirror retainers; a cooling element for supplying coolant to said first coolant passage and said second coolant passage, and circulating said coolant; and a solenoid valve provided in said second coolant passage, and adjusting flow rate of said coolant of said second coolant passage.