Patent ID: 9402297
Filing Date: 2016-07-26
CPC Classification: H05G

Claim Text:
1. An apparatus used with a laser apparatus, the apparatus comprising: a chamber; a target supply configured to supply a target to a first region inside the chamber; a laser beam focusing optical system configured to focus laser beams on the first region, the laser beams including a pre-pulse laser beam with which the target is irradiated and a main pulse laser beam with which the target is irradiated subsequent to the pre-pulse laser beam; a laser apparatus configured to generate the pre-pulse laser beam having a pulse duration of less than 1 ns and to generate the main pulse laser beam; and an intensity distribution control optical system configured to control intensity distribution along a first cross section of the pre-pulse laser beam, the first cross section being located in the first region, the intensity distribution along the first cross section has a second region in which a variation value C={(Imax−Imin)/(Imax+Imin)}×100(%) is equal to or less than 20%, where Imax is the highest beam intensity in the second region and Imin is the lowest beam intensity in the second region, an area of the second region being larger than an area of a second cross-section of the target, the second cross-section being a maximum cross-section perpendicular to the traveling path of the pre-pulse laser beam.