Gas laser oscillator having a gas flow smoothing device to smooth gas flow in the electrical discharge region

Claim 1

An axial flow type gas laser oscillator comprising: an electrical discharge tube having an inlet having an outer circumference and an annular gap for introducing a gas flow to the inside thereof, and an outlet; a pair of electrodes, installed along the longitudinal length of said electrical discharge tube with predetermined separation length, for producing an electric discharge inside the gas flow supplied to said electrical discharge tube; an optical cavity defined by a pair of mirrors and extending through the inside of said electrical discharge tube; a heat exchanger for cooling the gas flow which is heated by the electric discharge produced between said pair of electrodes, said heat exchanger having an inlet and an outlet; a first connecting tube, connecting the outlet of said electrical discharge tube with the inlet of said heat exchanger, for guiding the heated gas flow to said heat exchanger; a second connecting tube, connecting the outlet of said heat exchanger with the inlet of said electrical discharge tube, for guiding the cooled gas flow to said electrical discharge tube; a flow control unit provided at the inlet of said electrical discharge tube, said flow control unit comprising: (a) a flow control valve, slidably fitted around the outer circumference of said electrical discharge tube where the annular gap is formed, for changing the size of the annular gap, said flow control valve also having an outer circumference; and (b) a gas flow smoothing device, provided around the outer circumference of the flow control valve, for covering the annular gap and smoothing the gas flow flowing into the said electrical discharge tube through the annular gap.