Abstract: The energy conversion efficiency from light that is to be converted to converted light of a wavelength conversion device is adjusted so as always to be kept stably at a maximum. The wavelength conversion device is provided with a laser light source 10 for generating a fundamental wave light, a nonlinear optical crystal 16 into which the fundamental wave light is made to enter to generate converted light, and an optical path adjusting portion 30 for adjusting the direction of propagation of the fundamental wave light and the position of the light beam of the fundamental wave light in order to make the fundamental wave light enter the nonlinear optical crystal 16 while satisfying phase matching conditions.

Abstract: The energy conversion efficiency from light that is to be converted to converted light of a wavelength conversion device is adjusted so as always to be kept stably at a maximum. The wavelength conversion device is provided with a laser light source 10 for generating a fundamental wave light, a nonlinear optical crystal 16 into which the fundamental wave light is made to enter to generate converted light, and an optical path adjusting portion 30 for adjusting the direction of propagation of the fundamental wave light and the position of the light beam of the fundamental wave light in order to make the fundamental wave light enter the nonlinear optical crystal 16 while satisfying phase matching conditions.