Abstract: A beam homogenizer for surface modification comprises: a first lens array configured to split a laser beam, irradiated from a laser beam irradiation unit, into a plurality of beamlets; a second lens array configured to transmit the plurality of beamlets and comprising a plurality of lenslets corresponding to the first lens array; and a focusing lens configured to focus the plurality of beamlets, transmitted through the second lens array, onto a surface of a target. The beam homogenizer further comprises: a plasma generation-preventing unit disposed between the first and second lens arrays and configured to prevent plasma from being generated in the focal zone of the beamlets; or a damage-preventing unit disposed between the focusing lens and the target and configured to prevent the focusing lens from being damaged by energy generated when the plurality of beamlets is irradiated onto the target.

Abstract: A beam homogenizer for surface modification comprises: a first lens array configured to split a laser beam, irradiated from a laser beam irradiation unit, into a plurality of beamlets; a second lens array configured to transmit the plurality of beamlets and comprising a plurality of lenslets corresponding to the first lens array; and a focusing lens configured to focus the plurality of beamlets, transmitted through the second lens array, onto a surface of a target. The beam homogenizer further comprises: a plasma generation-preventing unit disposed between the first and second lens arrays and configured to prevent plasma from being generated in the focal zone of the beamlets; or a damage-preventing unit disposed between the focusing lens and the target and configured to prevent the focusing lens from being damaged by energy generated when the plurality of beamlets is irradiated onto the target.

Abstract: A laser amplifier capable of achieving a high output by offsetting distortion of an amplified laser beam. The laser amplifier includes: first and second amplification media which amplify a penetrating laser beam; a pre-compensation lens unit which pre-compensates for a laser beam irradiated to the first amplification medium so as to offset a thermal lensing effect generated in the first amplification medium and the second amplification medium; a first polarizing and penetrating mirror inclined to the laser beam irradiated to a front end of the first amplification medium and allowing a laser beam that vibrates in a specific direction to penetrate and reflecting a laser beam that vibrates in another direction; a polarization conversion plate provided at a rear side of the second amplification medium and changing a vibration direction of the laser beam penetrating the second amplification medium; and a first reflection mirror for reflecting a laser beam.