Patent ID: 7173954

Claim:
A gas laser oscillation device, comprising: a plurality of discharge sections that are respectively provided with electrodes for discharge; a plurality of power sources for discharge excitation that supply discharge power to the discharge sections and are respectively connected with the electrodes of the plurality of discharge sections; means for changing output mode, including: means for adjusting a distribution of an amount of discharge power supplied to the discharge sections, so far as the amount of discharge power supplied to any one of the discharge sections is not zero; and means for changing combinations of beam modes that are different from one another, beams being excited in at least two discharge sections; wherein said plurality of discharge sections include at least two discharge sections in which mutually different beam modes are excited when respective independent discharges are produced, based on one of (a) and (b): (a) the electrodes provided in each of the discharge sections differ from one another in regard to at least one of dimensions, shape and construction; and (b) the discharge sections differ from one another in regard to at least one of dimensions and shape.