This invention relates to a cross flow type laser device in which the direction of oscillation of the laser device and the direction of circulation of a laser medium or gas cross at right angles.
Generally, the cross flow type laser device is requested to have the following devices.
(1) A vacuum container of a high air tightness for preventing leakage of the laser medium and entrance of impurities. PA0 (2) A drive device for circulating the laser medium in the vacuum vessel. PA0 (3) A guide duct ensuring a smooth circulation of the laser medium. PA0 (4) A cooling device for maintaining the temperature of the laser medium at a low value.
One example of the prior art cross flow type laser device provided with the four devices described above is shown in FIG. 1 which is constituted by a highly air tight vacuum vessel 1, a propeller fan 2, guide ducts 3, a radiator 4, etc. The laser medium is circulated by the fan 2 through a circulation path shown by arrows. In FIG. 1, although the circulation path is shown two dimensionally, at a discharge portion at which discharge electrodes 5 are provided, the circulation path is formed such that the laser medium flows from the rear side to the front side of the sheet of drawing.
In the discharge portion, continuously circulating laser medium is continuously excited by electric discharge between discharge electrodes 5 to form an inverted distribution region in the discharge portion. The energy stored in the inverted distribution region is taken out as a laser light beam L by a photoresonator constituted by a front mirror 6 and a rear mirror 7 disposed at right angles with respect to the flow of the laser medium.
The laser medium whose temperature has been raised while passing through the discharge portion is cooled by the radiator 4 and the laser medium is returned again to the inlet of the fan 2.
In the prior art cross flow type laser device, since fan 2, guide ducts 3 and radiator 4 are incorporated into the vacuum vessel 1 to form the circulating path, these are many points at which the laser medium expands and contracts and corners in the circulating path which increase the pressure loss of the laser medium. For this reason it is necessary to use a fan 2 having a large output and size and to use a large radiator 4. Accordingly, the overall efficiency of the laser device is lowered.