| CPC H01S 3/225 (2013.01) [H01S 3/0835 (2013.01); H01S 3/2308 (2013.01)] | 18 Claims |
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1. A laser apparatus comprising:
a master oscillator configured to emit a laser beam;
an amplifier including an optical resonator and configured to amplify the laser beam emitted by the master oscillator in the optical resonator; and
a phase shift structure disposed on an optical path between the master oscillator and the amplifier at a position closer to the amplifier than a middle point of the optical path,
the phase shift structure including a plurality of cells having different phase shift amounts for the laser beam,
the cells having a disposition interval of 80 μm to 275 μm inclusive, wherein
the amplifier includes a pair of discharge electrodes disposed opposite each other across a discharge space through which the laser beam passes, and
when a Z direction is defined to be a traveling direction of the laser beam emitted from the amplifier, a V direction is defined to be a discharge direction of the discharge electrodes, an H direction is defined to be a direction orthogonal to the V direction and the Z direction, a first direction is defined to be an in-surface direction of the phase shift structure corresponding to the V direction in a beam section of the laser beam emitted from the amplifier, and a second direction is defined to be an in-surface direction of the phase shift structure corresponding to the H direction in the beam section,
a length of each of the cells in the first direction is different from a length of the cell in the second direction.
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