Patent ID: 7817334

Claim:
A wavelength conversion element comprising: a second harmonic wave generating element provided with: (i) an entrance surface; (ii) an emission surface; (iii) a cyclic polarization inversion structure; and (iv) a first wavelength dispersive optical element disposed on the entrance surface side of the second harmonic wave generating element; and a second wavelength dispersive optical element disposed on the emission surface side of the second harmonic wave generating element, the second harmonic wave generating element converting an incident fundamental wave having a first wavelength into a second harmonic wave having a second wavelength, and emitting the second harmonic wave; the cyclic polarization inversion structure being configured so as to be able to match a phase of the second harmonic wave in a pseudo manner; wherein the second wavelength being different than the first wavelength; and the first wavelength dispersive optical element having a first diffraction surface that diffracts an incident light beam with a diffraction angle increasing in accordance with a wavelength of an incident light beam to disperse the incident light beam by the wavelength of the incident light beam, and that emits the light beam dispersed in the first diffraction surface towards the second harmonic wave generating element; and the second wavelength dispersion optical element having a second diffraction surface that diffracts an incident light beam with a diffraction angle increasing in accordance with a wavelength of the incident light beam to disperse the incident light beam by the wavelength of the incident light beam, the second diffraction surface being configured to have a diffraction angle, which corresponds to a light beam with a predetermined wavelength, substantially identical to a diffraction angle of the first diffraction surface, which corresponds to a light beam with the predetermined wavelength.