Patent ID: 7342948

Claim:
A blower used for a laser oscillator, the laser oscillator comprising: an electric discharge tube in which a laser medium of gas is circulated; electrodes arranged at the electric discharge tube; a pair of reflecting mirrors arranged at both end portions of the electric discharge tube; a heat exchanger for cooling the laser medium in the electric discharge tube; and a circulating passage through which the laser medium is sucked from the electric discharge tube and introduced into the heat exchanger and the laser medium, which has been cooled by the heat exchanger, is returned to the electric discharge tube, wherein the blower circulates the laser medium between the electric discharge tube and the circulating passage in the laser oscillator, a casing having a suction port and an exhaust port; and a blade pivotally supported in the casing so that the blade can face the suction port and the exhaust port, the blade has an extending part, which extends along an inner surface of the casing in a cross section including the rotary center line, wherein the blade is formed into a shape in which a diameter of the blade is different according to a position on a cross section perpendicular to a rotary center line of the blade, and a gap between the extending part of the blade and the casing in a portion in which the diameter of the blade is relatively large is larger than a gap between the extending part of the blade and the casing in a portion in which the diameter of the blade is relatively small.