Abstract: A laser maintaining and repairing apparatus including a laser oscillator 7, beam guiding apparatus 8 connected to guide a laser beam of the laser oscillator 7, and emitting head 12 for converging the laser beam from the beam guiding apparatus 8 and emitting the beam to a portion to be processed. The beam guiding apparatus 8 includes liquid-tight tubular beam guiding members 9a to 9h. The beam guiding members 9a to 9h are provided with reflecting members 13a, 13b and at least one of mechanisms 10a, 10b and 11a, 11b for providing horizontal turning, horizontal extending, vertical turning and vertical extending operations at the beam guiding members 9a to 9h. With the laser maintaining and repairing apparatus of the noted structure, a laser beam of high energy density can be utilized and processing by the laser beam can be facilitated or the applying range can be increased.

Abstract: An underwater laser processing method is carried out by irradiating, through a laser beam irradiation apparatus, a laser beam having a high output, a short pulse and a visible wavelength to a surface of a structure immersed in a water to improve residual stress of a material of the surface of the structure and remove a crack or a CRUD thereof. The laser beam irradiation apparatus comprises a pulse laser device suspended into a water in which a metal material is accommodated from an upper side thereof for irradiating a laser beam having a visible wavelength to a processing position, a beam strength adjusting device for adjusting an output per 1 pulse of a laser beam generated by the pulse laser device and a mechanism for adjusting a spot diameter and a multiplexing ratio of an irradiated beam.

Abstract: An underwater laser processing method is carried out by irradiating, through a laser beam irradiation apparatus, a laser beam having a high output, a short pulse and a visible wavelength to a surface of a structure immersed in a water to improve residual stress of a material of the surface of the structure and remove a crack or a CRUD thereof. The laser beam irradiation apparatus comprises a pulse laser device suspended into a water in which a metal material is accommodated from an upper side thereof for irradiating a laser beam having a visible wavelength to a processing position, a beam strength adjusting device for adjusting an output per 1 pulse of a laser beam generated by the pulse laser device and a mechanism for adjusting a spot diameter and a multiplexing ratio of an irradiated beam.