Patent ID: 7792163

Claim:
A harmonic generator, comprising: a laser light source for generating a laser light; a condensing member for condensing the laser light; a nonlinear crystal having a poled structure formed to be phase-matched with the laser light condensed by the condensing member; and a displacing member for relatively displacing a focus position of the laser light from the condensing member and the nonlinear crystal, wherein the poled structure has a structure in which poled portions are arranged and equally spaced in a first direction parallel to an optical axis of the laser light from the condensing member, and the poled portions extend in a second direction orthogonal to the first direction, and the poled portions are unequally spaced in a third direction orthogonal to the first and second directions, wherein in the poled structure, an irradiation range is set which has a wavelength conversion efficiency of 90% or higher of a maximum conversion efficiency of a wavelength conversion element so that a dimension in the first direction and the dimension in the second direction become larger than the dimension in the third direction, and wherein the displacing member relatively displaces the focus position and the nonlinear crystal such that, within the irradiation range, the focus position of the laser light is oscillated at least in one of the first and second directions without stopping at the same position for longer than a predetermined period.