| 摘要 |
PURPOSE: To provide a wavelength conversion device elongating the life of a wavelength conversion element and improving the conversion efficiency of the wavelength conversion element. CONSTITUTION: A laser beam emitted from a laser light source 1 is converged by a condenser lens 2a to be made incident on the wavelength conversion element 3 consisting of a non-linear optical crystal. The wavelength conversion element 3 is arranged on a laser light side of the converged position of the condenser lens 2a. A part of the laser beam made incident on the wavelength conversion element 3 is wavelength converted to be emitted from the wavelength conversion element 3. Although the laser beam emitted from the condenser lens 2a shows a nearly ideal Gauss distribution until it reaches the converged position, a shape of a space intensity distribution is deteriorated from the vicinity passing through the converged position. Thus, by arranging the wavelength conversion element 3 on the above-mentioned position, the pharomeror that the laser beam having a spike-like peak in the space intensity distribution is made incident is eliminated, and the life of the wavelength conversion element 3 is elongated, and the conversion efficiency is improved.
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